Distributional Studies of Parasitic Arthropods in Utah Determined As Actual and Potential Vectors of Rocky Mountain Spotted Feve

Brigham Young University Science Bulletin, Biological Series

Volume 1 Number 1 Article 1

3-1-1955

Distributional studies of parasitic arthropods in Utah determined as actual and potential vectors of Rocky Mountain spotted fever and plague: with notes on vector-host relationships

D Elden Beck Department of Zoology and Entomology, Brigham Young University

Follow this and additional works at: https://scholarsarchive.byu.edu/byuscib

Part of the Anatomy Commons, Botany Commons, Physiology Commons, and the Zoology Commons

Recommended Citation Beck, D Elden (1955) "Distributional studies of parasitic arthropods in Utah determined as actual and potential vectors of Rocky Mountain spotted fever and plague: with notes on vector-host relationships," Brigham Young University Science Bulletin, Biological Series: Vol. 1 : No. 1 , Article 1. Available at: https://scholarsarchive.byu.edu/byuscib/vol1/iss1/1

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Brigham Young University Science Bulletin, Biological Series by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. S-/f/fi p£'zl BrighamBri Young University

Science Bulletin *'^s co^^

BIOLOGICAL SERIES — VOLUME I, NUMBER "y^^f^s/-^

March h 1955

DISTRIBUTIONAL STUDIES OF PARASITIC ARTHROPODS IN UTAH, DETERMINED AS ACTUAL AND POTENTIAL VECTORS OF ROCKY MOUNTAIN SPOTTED FEVER AND PLAGUE, with notes on VECTOR-HOST RELATIONSHIPS

by D ELDEN BECK

Published by BRIGHAM YOUNG UNIVERSITY

Provo, Utah

Brigham Young University Science Bulletin

BIOLOGICAL SERIES — VOLUME I, NUMBER I

March J, 7955

DISTRIBUTIONAL STUDIES OF PARASITIC ARTHROPODS IN UTAH, DETERMINED AS ACTUAL AND POTENTIAL VECTORS OF ROCKY MOUNTAIN SPOTTED FEVER AND PLAGUE, with notes on VECTOR-HOST RELATIONSHIPS

by D ELDEN BECK

Published by BRIGHAM YOUNG UNIVERSITY

Prove, Utah

TABLE OF CONTENTS

Introduction 1 Objectives 1

Survey procedure - 1 Host collections 2 Consortes collections 2 Problems of survey related to geography 2 Biotic communities 7

Acknowledgments - 10

Part I Plague Vector Investigations 15 Introduction 15 Discussion of the disease 15

Etiology - 15 Host relationship 15 Historical resume 16

Early history _ 16

Plague in western U. S _ 17

Plague in Utah _ 17

Plague and endemicity _ 18

Plague and plague vectors _ 19

Seasonal variations in vector populations _ 22

Reservoir hosts and plague vectors _ 22

Reservoir hosts of plague in Utah _ 22

Fleas as plague vectors in Utah _ 24

Fleas and murine plague in Utah _ 24

Capable vectors _ 25

Potential vectors _ 32 Summary and conclusions 35 Literature cited 35

Part II Rocky Mountain Spotted Fever Vector Investigations 38 Introduction 38

Etiological agent . 44 Distribution of the disease and case fatality 44 In the United States 44 In Utah 45 Host relationship and the disease 45 Vector and disease relationship in North America 46 Vector and disease relationship in Utah 47

Life history and seasonal variation 47 Dennacentor andersoni 47 D. parumapertus 50

Haemaphysalis leporis - palustris 52 Vector host association and distribution 52 D. andersoni 52 D. parumapertus 54

D. albipictns _ 54

H. leporis - palustris _ 54

Ornithodoros parkeri _ 54 Summary and conclusions 60

Literature cited 61 LIST OF ILLUSTRATIONS

INTRODUCTION Page

Figure 1. Principal physiographic areas of Utah 3

Figure 2. Great Basin and Colorado River Basin regions in Utah 4

Figure 3. Great Basin and Colorado River Basin regions in Utah with reference to the political subdivisions 5

Figure 4. Physiographic map of Utah on which are listed the principal biotic communities, the primary physiographic regions as well as drainage basins 6

Figure 5. Desert island mountains created by intrusive uptbrusts in Grand and San Juan Counties 8

Figure 6. Southern Desert Shrub Community 9

Figure 7. Shallow, desert drainage basin near Green River, Emery County 9

Figure 8. Farming village of Fruita in Capitol Reef National Monument, Wayne County 11

Figure 9. Great Basin desert flatland as seen at the Desert Range Experiment Station in western Millard County 11 Figure 10. Juniper woodland about 3 miles north of Jericho, Juab County, on U.S. Highway 6 12

Figure 11. Transition Zone as found on the Wasatch Range in Provo Canyon of Utah County .. 13 Figure 12. Boreal environment near timberline in the La Sal mountains area of Grand and San Juan Counties 13

PART I

Table 1. Vector-host relationship in Utah collections for vectors of plague listed as capable vectors 20-21

Table 2. Vector-host relationship for vectors of plague in Utah listed as potential vectors 26-27

Table 3. Distributional pattern by counties in Utah for fleas implicated as capable vectors of plague - 28

Table 4. Distributional pattern by counties in Utah for fleas implicated as potential vectors of plague 29

Table 5. Distribution by County of potential and capable plague vectors with reference to hosts which have been shown to be plague implicated 30-31

Figure 13. Distributional pattern for those species of fleas in Utah listed as the effective capable vectors for plague 33

Figure 14. Map showing the general distributional pattern for fleas listed as capable vectors for plague 34

PART II

Table 1. Rocky Mountain spotted fever cases in Utah 40

Table 2. Rocky Mountain spotted fever cases in Utah from 1924 to 1932 41

Table 3. Rocky Mountain spotted fever cases in Utah from 1933-1942 42

Table 4. Rocky Mountain spotted fever cases in Utah. Case totals and fatality rates for State and Counties from 1915 to 1942 43

Table 5. Vector-host relationships for D. andersoni and D. parumapertus with reference to collections made at low and high altitudes 55

Table 6. Distribution by county of capable and potential vectors of Rocky Mountain spotted fever in Utah 56

Figure 1. Seasonal population variations 48

Figure 2. Collection records for larvae and nymphs of D. pannnapertus from specific hosts .. 48

Figure 3. Seasonal population variations for adult, larval, and nymphal ticks of Haemaphysalis leporis-jmliisti-is 49

Figure 4. Seasonal population variations for larval and nymphal ticks of Dermacentor andersoni collected at high altitudes 49

Figure 5. Comparative numbers of larval and nymphal tick collections of Dermacentor sp. .. 51

Figure 6. Seasonal population variation of larvae and nymphs at Lucin and Cedar Valley in the Great Basin region in Utah 56

Figure 7. Distributional pattern for collections of Dermacentor andersoni in Utah 57

Figure 8. Distributional pattern for collections of Dermacentor parumapertus in Utah 58

Figure 9. Distributional pattern for collections of Haemaphysalis lepoi-is-palustris in Utah .... 59

U .

DISTRIBUTIONAL STUDIES OF PARASITIC ARTHROPODS IN UTAH, DETERMINED AS ACTUAL AND POTENTIAL VECTORS OF ROCKY MOUNTAIN SPO'lTED FEVER AND PLAGUE, WITH NOTES ON VECTOR-HOST RELATIONSHIPS by D Elden Beck Department of Zoology and Entomology

INTRODUCTION

Preliminary investigations were s1 ;rted on grazing domains, wilderness areas and mining this project in the spring of 1948. The Division locations in both desert and mountainous situ- of Research Grants and Fellowships of the ations were surveyed. Since the hinterland National Institutes of Health, Department of areas in the southeastern section of Utah are Health, Education, and Welfare, U. S. Public being invaded by many hundreds of uranium Health Service, established a research grant for prospectors, it was felt that significant surveys this study at the Brigham Young University in this extensive area would be of value from a September 1, 1950. The author, a member of public health point of view. Sui"veys were also the faculty of the Department of Zoology and made in some of the national parks and monu- Entomology at the grantee institution, was ments within the S'.ate of Utah, visited annually named the principal investigator. The project by many thous-^'s of tourists. Finally, spot was designed for a three year period of study. checking was done along the principal arterial Most of the work originally planned has now state and federal highways in Utah. been completed and is being reported upon in Field surveys were conducted on a year- this paper. round basis, insofar as host animals were available and access to areas was possible. Hosts were Objectives of the study were as follows: captured both alive and dead, by whatever

1 To locate and identify the species of known means best suited the conditions of collecting, vectors of plague and Rocky Mountain spot- Several types of live traps were utilized. Some ted fever in Utah. types of live traps were more effective in trapping certain animals than others, and certain 2. To specifically identify hosts with which traps were effective others differ- the known vectors would be associated and more than in ent kinds of habitats different show their geographic distribution. and at seasons. Dead hosts were usually captured by snap traps 3. To determine and locate in Utah the known or by shooting with the appropriate calibre or reservoir hosts for plague and Rocky Moun- gauge of gun. tain spotted fever.

4. To make observations on vector-host re- If an animal were captured alive, it was lationships. then taken to the field station or laboratory

5. To record, insofar as possible, information where it was chloroformed and the body care- on vector populations in order to determine fully examined for parasites. Dead animals seasonal variations if any. were placed directly from the trap into paper bags and then taken to the field station or lab- 6. To conduct investigations both in the field oratory where the body was subjected to the and by laboratory studies which would help chloroform treatment which drove the para- solve some problems related to life histories sites from the host or made it possible for the of various species involved as vectors of parasites to be brushed or otherwise removed Rocky Mountain spotted fever and plague. from the body of the host. Once the parasites were collected, they were placed in containers General survey procedure: with identifying lables. A field number on Those areas of the State where the great- this lable referred to the field records which est concentration of people was located were were made up in detail. Tliese data included surveyed first. Following this, the more outly- the name of the host, sex, number of parasites, ing towns and cities were studied. Vast stock date of collection, place, collector, and a general Brigham Young University Science Bulletin description of ecological conditions where the 2. There were about 25,000 specimens of ticks collection was made. of the families Ixodidae and Argasidae col- A great number of nest collections were lected. This collection includes 14 species made. The nests were placed in "Berlese" fun- of 6 genera. nels for the removal of consortes. All collec- 3. Approximately 280,000 specimens of mites tions, whether taken from the host body or have been taken during the period of this from the nest, were preserved in 70% ethyl study, representing an unknown number of alcohol. Various sizes of glass vials were used. species. For the most part, procaine drug vials were the 4. Some 3,000 specimens of Mallophaga (bit- best containers for specimens. Hemopathic glass ing Uce) have been collected representing vials were used to contain engorged ticks. an unknown number of species. Once the specimens were collected, they 5. Close to 12,000 specimens of Anoplura were brought to the laboratory and prepared (sucking lice) have been collected also rep- for identification. For the fleas, it meant taking resenting of species. the steps necessary to clear and mount the an unknown number specimens on microscope slides. Fortunately, 6. About 20,000 specimens of various other the ticks needed no special treatment in order arthropods have been collected. These rep- to be properly identified. With identification resent immature and mature stages of or- complete, the data for that specimen were re- ganisms belonging to the true bugs {Hem- corded on a master file sheet from which in- iptera), beetles {Coleoptera) , flies (Dip- formation could be obtained. tera), pseudoscorpions, spiders, and others.

Host collections: PROBLEMS OF SURVEY RELATED TO UTAH GEOGRAPHY 1. Fifty- nine species and subspecies of mammals, representing 29 genera and approxi- Utah is divided along a north-south axis mately 5,500 individual animals were col- by mountain ranges and high plateaus (Fig. 4). lected. All animals were carefully ex- The principal mountain range areas in the amined for medically important ectopara- north-central region consists of the Wasatch sites, as well as other consortes. Range, having a north-south axis, and the Uin-

2. Eight species of reptiles, representing 8 ta Mountains which extend east and west near genera and 86 individual animals were the northeast border (Figs. 1 and 4). South of collected. the Uintah Mountains and South of the Wasatch Mountains (the latter terminating at 3. Twenty-six species of birds, representing place the town of Nephi is 21 genera and 78 individual birds were about the where located) is the "plateau" country of the State. collected. This mountain range and plateau combination 4. Nests of mammals were collected because divides the State more or less into eastern and nesting sites harbor immature and mature western divisions. The western unit is, in the stages of the vectors; 277 nests, representing main, a part of the Great Basin region (Figs 1, 7 genera and 9 species and subspecies of 2, 3, and 4) and has its separate drainage pat- mammals were taken. tern. This is likewise the case with the eastern portion of the State which is a part of the Colo- Consortes collections; rado River Basin.

It was decided early in the project that The eastern half is bordered on the north careful removal and preservation should be by the unusual east-west range, the Uinta done for all arthropod consortes although par- Mountains (Fig. 1) With the exception of the ticular attention was given to those forms for Bear, Weber, and Provo Rivers, which flow which this project was established. Listed be- into the Great Salt Lake, the drainage from low are the closely approximated numbers of all tliis mountain range is to the Colorado River consortes removed from the hosts as well as Basin. The southern portion of the Colorado those collected by Berlese funnel extraction of River Basin within the confines of Utah is consortes from host nests: very graphically described in U. S. Department

1. There were approximately 19,000 speci- of Interior National Park Service publication, mens of Siphonaptera collected. The total "A Survey of the Recreational Resources of the siphonapteron collection represents 82 spe- Colorado River Basin," (1950). cies and subspecies of 38 genera. "It is a wild and fantastically eroded Biological Series Vol. 1, No. 1, March, 1955

109 "T"

Figure 1. The principal physiographic areas of Utah. Brigham Young University Science Bulletin

Figure 2. The Great Basin and Colorado River Basin regions in Utah. Biological Series Vol. 1, No. 1, March, 1955

DAHO

ARIZONA

Figure 3. The Great Basin and Colorado River Basin regions in Utaii witii reference to the political subdivisions. Brigham Young University Science Bulletin

SCALt tlmin

^SOUTHERN DESERT SHRUB, COMMUNITY

Figure 4. A physiographic map of Utah on which are identified the principal biotic communities, the primary physiographic regions as well as drainage basins. Biological Series Vol. 1, No. 1, March, 1955

land of winding gorges and sandstone mesas ward to the Four-Comers, the only place in the whose vast expanses are punctuated at ir- United States where four states of the Union regular intervals by the isolated, steeply up- border each other. thrust masses of the Henry, Abajo, and Nava- There are extraordinary "desert island jo Mountains. With the exception of the mountains" located in both the Great Basin mountain summits, which are cool and moist, and Colorado River Basin areas. Such moun- the greater portion of the area receives but tains are the Henry Mountains, the La Sal little snowfall in winter and is characterized Mountains (Fig. 5), and the Abajo Mountains by a long, warm summer season. Average in the plateau region of the Canyon Lands. In temperatures are higher than those of valleys the plateau country south of the Wasatch Range to the north, in conformity wdth the decrease are found high mountain peaks rising to over in latitude, but lower than those of deserts 11,000 feet in elevation. In the Great Basin to the south. The annual precipitation ranges are such liigh mountains as the Deep Creek from about 6 to 14 inches, with the greatest Mountains wdth elevations above 12,000 feet. amount coming from thunderstorms during This highly variable topography of the July and August." State of Utah makes a natural history survej' "This desolate but spectacular scenic very difficult, and a major portion of the funds sandstone area is referred to in this report as allocated for this study has had to be expended Canyon Lands of southeastern Utah." for travel. The Canyon Land topography continues on eastward into the state of Colorado. (Figs. BIOTIC COMMUNITIES OF THE STATE 2 and 4). The western portion of the Colorado OF UTAH River Basin in Utah is elevated into a high There is no intent on the part of the author plateau type of typography. The western faces to discuss in detail the biotic areas of Utah. of these plateaus are deeply cut into countless However, it wall materially help the reader to canyons which drain westward into the Great orient himself ecologically if he could at least Basin. The eastern escarpments are likewise get a generalized concept of the biotic communi- cut into canyons which for the most part drain ties in which these surveys were conducted. into the Colorado River Basin. Utah's diversified topography provides for accessibility, there From the standpoint of a comparable diversification in biotic com- is relatively little hindrance in travel through- munities. There are altitudinal ranges from out the Great Basin area except perhaps in the 2,760 feet above sea level at St. George in Wash- of Great Salt Lake Desert region and the tops ington County, to King's Peak of the Uinta the few high mountains. The central moimtain Mountain range in Daggett County, with an (block fault the Uinta ranges mountains), elevation of 13,498 feet. Wide variations in soil part of Mountain range and the western-most composition, fertility, structure, and alkalininty the Colorado River Basin to a great extent also likevdse causes marked differences. Conse- have been opened to travel. quently, the flora and fauna varies markedly. The Canyon Land country, however, pre- There are three major biotic habitats in sents next to impossible obstacles in road build- Utah, when considered in the broadest sense. ing even though uranium explorers are now There are deserts, foothills, and mountains. fingering trails into some of this most formida- Each of these major habitats may be still fur- ble and remote country in the United States. ther subdivided into natural biotic communities. There are no east-west roads in the southern For this study the above-mentioned habitats part of the State of Utah as are found in the have been considered as follows: northern half, owing to the impassability of the The desert region: rugged terrain. To go from the southwestern The desert is conveniently separated into comer to the southeastern comer of the State the northern and southern deseret shrub biomes the present time necessitates a circumventous as described by Fautin (1946). route northward to the central part of the state The southern desert shrub biome in Utah and then southward and eastward outside of is geographically located in the southwestern Utah into Colorado, New Mexico, and thence comer of the state (Fig. 4). It is identified lo- northward into the Four-Comers area. On the cally as the Virgin Valley and is a part of the other hand, one could take a southern route Colorado River Drainage system. A very mild which would carry him into the State of Ari- climate exists during the winter; however, zona, over desolate desert trails and then north- maximum summer temperatures are common p i-j o M C

3 O O S C _

5' K

t-j.t:":- ''*8jpSj»—>•

r^tf.

<*:>#.

are Cresote bushes, Co- Figure 6. Southern Desert Shrub Community: The dark colored plants villea tridentatum Vail. The lighter colored ones are Krameria glandulosa Rose and Painter. The Valley mountains which foreground is part of the Virgin Valley area. In the background are the Pine rise to more than 10,000 feet above sea level. table lands possessing shal- Figure 7. In the east central portion of Utah are extensive plateaus and of low drainage basins, salt flats, mesas and desert canyons. This picture was taken near the town country Green River, Emery County. It shows a shallow desert drainage basin of a rugged canyon eastern as indicated by the rocky formation in the distance. This rocky wall-like formation marks the flank of the San Rapheal Swell.

»9f ^Cl^fi^'^i"}''

, "^^^ii^-:2? ''"% V • V. 10 Brigham Young University Science Bulletin

above 100° F. It is a land of arid sand and brush of several species, serviceberry, elderberry barren rock. Creosote, mesquites, and choUa and maple (Fig. 11). In the southern part of cactus are distinctive floristic indicators. This the state, the ponderosa pine forests denote a hot desert situation is also distinguished under change from a strictly mountain foothill brush the life zone concept of Merriam (1898) as the land to one of a montane forest type. Lower Sonoran Zone (Fig. 6). It occupies a very small geographic area in comparison to the Mountain communities: '

rest of the state. Nevertheless, it does present The entire complex of montane communi- a unique ecological type. ties is frequently referred to as Boreal which The northern desert shrub biome consti- may be broken down into Alpine, Hudsonian, tutes the greater surface area of Utah (Figs. 4, and Canadian life zones, listed here from high- 7, 8, and Under the life zone concept this 9). est to lowest in altitude, respectively. From the community would be designated the Upper standpoint of the various boitic communities Sonoran Zone. It is contained in the Great the Alpine area is treeless and tundra-like. Basin area except the higher mountains. In the Grasses, sedges. Parry's Primrose, lichens, and Great Basin region of Utah, the topography is certain species of buttercups are common plant one of extensive flatlands interrupted at inter- indicators. The Hudsonian zone comprises part vals by low-lying block fault mountain ranges of the very distinctive montane forest communi- extending along a north-south axis. All of the ty. Here are found the Engleman and blue Colorado River Basin within the state, except spruce, alpine fir, lodge pole, foxtail, and limber the high mountain ranges and plateaus, is pine. Extensive grassy parklands and meadows characterized this northern desert shrub com- by may also be found in the montane forest areas, munity. There are lowlands, valleys, plains, but it is primarily a conifer community. The the desert canyons, low-lying mesas, shallow so-called Canadian zone is also a part of the drainage basins, and salt flats (Fig. 7). Found Montane forest, but altitudinally it is found in both the Great Basin and Colorado River at the lower limits of this community. The shrub Drainage area of the northern desert quaking aspen, red cedar (jmiiper), mountain community are such plants as tri-dent sage, sumac, bracken fern, and blue spruce are some rabbit brush, alkali plants greasewood, saltbush, common examples of plants found here. Doug- of various species, hackberry, white sage, black- las fir and White fir, however, are the best brush, pinyon pine and juniper. Each of these plant indicators for this community (Fig. 12). may be and is greatly restricted by such factors as soil type, water supply and degree of alka- HISTORICAL RESUME linity. The upper limits of the northern desert Plague and Rocky Mountain spotted fever shrub community in Utah are reached at the are to be discussed in separate sections of this foothills of the mountains and plateaus. The paper. Significant historical information will "pigmy forest" or Pinyon-Juniper woodland be given at the appropriate place in the separate (Fig. 10) is the most common plant community sections designated for each subject. found at these elevations. ACKNOWLEDGMENTS Foothill communities: The following institutions and organiza- As the name implies, these foothill areas tions have provided the material means to make are located at the meeting place where the this project possible and to bring it to comple- mountains, mountain-high plateaus, and mesas tion: The National Institutes of Health, Di- merge into the valleys. Here are found very vision of Research Grants and Fellowships pro- distinctive and interesting biotic communities. vided the major source of funds for the project. Ecologically they represent an ecotonal situ- The Brigham Young University, through the ation. They are the meeting places of northern Department of Zoology and Entomology, made (Boreal) biota, common to the mountain ranges, space and equipment available and also con- and the southern (Sonoran) biota found in the tributed supplemental funds from their research desert valleys. Under the life zone concept, budgets. The Research Department at the Brig- they would be classified as the Transition Zone. ham Young University, under the direction of In north and north-central Utah, best demon- Dr. Harvey Fletcher, generously contributed strated at the foothills region of the Wasatch funds for printing this report. The regional Mountains, are the chaparral shrubs of oak- office of the National Park Service was most Figure 8. The farming village of Fruita in Capital Reef National Monument, Wayne County. This is a typical desert canyon kind of topography in the plateau country of the Colorado Drainage system.

Figure 9. Great Basin desert flatland as seen at the Desert Range Experiment Station in western Millard County. The light colored shrub is White Sage Eurotia lanata (Pursh). The darker colored plants are predominantly Bud Sage Artemesia spinescens Eaton, and the shadscale Atriplex conferti- folia (Torr. & Frem.).

•"•f-t -^'>--'^^ ^^->.-^**-r-^-_ ^-

,3*' ,^^%-'3t \^ :f' 1 . ^.. *^'1 Figure 10. Juniper woodland about 3 miles north of Jericho, Juab County, Utah, on U.S. highway 6.

-» '^j- ,i

.• ,-. - - ^ - • . <•? ...1 i.iJJllPBii—p 2^r%vVr'*r* Figure 11. In the middle distance of the central part of the picture are the chaparral shrubs typical of the Transition Zone as found on the Wasatch Range in Provo Canyon of Utah County. On the tops of the mountains are sparse stands of conifers.

Figure 12. A boreal type of environment is exhibited by this mountain scene. It is near timberline in the La Sal mountain area of Grand and San Juan Counties, Utah.

t; -^?

,«* ^e

r^j^'. ..^.^^J

**.''.

L«'

&«": :' s->^. -??.;« **'ii v***- ..-.^te?^?^ =^ *-Vv»--*v' 14 Brigham Young University Science Bulletin cooperative in making permits available in or- members of the survey staff. Mr. Harold Stark, der that collections of rodents and lagomorphs of the U. S. Department of Healtli, Education, and Welfare, San Francisco, California, field in selected areas of several parks and monu- station, has carefully examined flea specimens ments could be made. Personnel of the Depart- of the genus Thrassis. Mr. Frank Prince, of ment of Entomology and Parasitology, Army the same office, has checked many specimens of Medical Service Graduate School, Washington, fleas of the genus Malaraeus. D.C., contributed taxonomic assistance. This Mr. Stark, while at the University of Utah was likewise the case with the Rocky Mountain as a graduate student produced a Master of Laboratory, Hamilton, Montana; the San Fran- Science thesis titled, "A Preliminary Study of cisco Communicable Disease Center station of Utah Fleas" which has not been published to the U. S. Department of Health, Education, date. It has an abundance of information which and Welfare. The Utah State Department of was helpful in many respects in this project. Health gave wholehearted cooperation in furn- Added importance is also attached to Mr. Stark's ishing needed statistical information. The unpublished manuscript in that Mr. Frank Brigham Young University library helped in Prince contributed some data to Mr. Stark re- processing inter-library loans and obtaining garding western fleas. The thesis has been many needed reference books required for this made available to me through the courtesy of study. Doctors George Knowlton and J. S. Stan- the University of Utah Library. Mr. Stark con- ford were very helpful in making available templates a more complete publication in the their collection of vectors at the Utah State Ag- near future dealing with Utah fleas and hence ricultural College at Logan. has withheld publishing his M.S. thesis. Many persons have worked with me for several years in gathering, compiling, and an- Dr. Clarence Cottam, dean of the College alyzing data relative to the project. Some of of Biological and Agricultural Sciences, Brig- these people are responsible for major facets ham Young University, read the manuscript of information, while others have been instru- and offered valuable suggestions on its com- mental only in bringing specimens to the lab- position. It was mainly through his interest oratory. For these greater or lesser acts of and effort that publication was made possible. Dr. C. I layward, of the of kindness I am very grateful. All of the thought- Lynn Department ful contributions have been important factors Zoology and Entomology at Brigham Young in contributing to the quality and completeness University, has been most helpful in corrobo- of this study. There are some names, however, rating taxonomic determination of host mam- which should receive special mention. mals. His advice on matters of ecological significance has also been appreciated and he like- For a major part of the duration of the wise has carefully edited this manuscript. Mr. project, I was fortunate in having three out- Merlin L. Killpack, mammalogist, has collected standing graduate students working with me. many hundreds of parasites in the northeastern Their labors have contributed greatly to the part of Utah and has submitted them to this success of the study. Without their help, the project. He, also, has spent several summers project would not have been possible of com- in field surveys on this project. Richard M. pletion. These men are Dorald M. Allred, Hansen, U. S. Public Health Service Fellow, Marvin D. Coffey, and Merlin L. Killpack. Microbiological Institute, University of Utah, Specialists for various taxonomic groups gave supplemented the collections of this survey by unstintingly of their time to corroborate de- his own collections of fleas and ticks collected terminations made by our staff, or made ac- during his studies with the squirrels of the genus curate determinations of "unknowns" sent to Citellus and others in Utah. them. Colonel Robert Traub and Captain Ver- Mr. John Wright, of the Utah State De- non J. Tipton of the Department of Entomology furnished the statistical and Parasitology, Army Medical Service Grad- partment of Health, of Rocky Mountain spotted uate School, helped with some siphonapteran data on incidence determinations. To Dr. William L. Jellison, fever in Utah. of the Rocky Mountain Laboratoiy, Hamilton, Other people, who have made general con- Montana, who helped with siphonapteran de- tribution to the project, are Mr. Fred C. Harm- terminations, and Mr. Glen M. Kohls, who ston, Roy J. Myklebust, Robert Liddiard, and J. helped with tick taxonomy, I owe a special Franklin Howell. All, with the exception of debt of gratitude. All during the investigation Mr. Harmston, were former students. Mr. they gave much encouragement and help to all Harmston is, at present, with the U. S. Depart- Biological Series Vol. 1, No. 1, March, 1955 15 ment of Health, Education, and Welfare. THE DISEASE PLAGUE I am personally indebted to Dr. Vasco M. Etiological aspect Tanner, Chairman of the Department of Zo- The infectious disease, plague, has as its ology and Entomology at the Brigham Young causative organism the bacilliform bacterium University. It was primarily through his ef- Pasturella pestis Yersin. According to Craig, forts that space and equipment needed were Faust and Miller (1951) the etiological agent made available for this study. of plague is a: Finally, I would be most ungrateful if I did "Gram-negative, pleomorphic, bipolar stain- not acknowledge the tireless, cooperative as- ing bacillus, which is non-motile, does not sistance given me by my wife, Florence. She form spores, but at times produces a capsule. has helped with field surveys and technical It was discovered by Yersin, in 1894, at the preparation of specimens. The careful record beginning of the extensive pandemic of the making and filing of data has without doubt disease which developed in Hongkong been a major undertaking, accurately and neat- (China) in that year." ly done. I cannot thank her too much. Host relationship

Plague is considered a disease of rodents PART I even though since antiquity devastating out- PLAGUE VECTOR INVESTIGATIONS breaks have occurred in mankind. From the INTRODUCTION standpoint of host-parasite relationships as well as the location of the bacterium in the body of This report, "should be considered as an the host, the disease is known under various attempt to facilitate the better understanding names. The most commonly used classification is murine, sylvatic and human or bubonic of the present status of the problem of vectors plague. and reservoirs of plague with a view to im- Non-native rodents as the gray or sewer proving our knowledge of the subject, particu- rat, Rattus norvegicus (Erxleben), the house larly considering that sylvatic plague is a di- or ship rat, R. rattus rattus (Linn.), and the sease of increasing importance, the control of black Alexandrine rat, Rattus rattus alexan- belong to the family of ro- which is still one of the main unsolved problems drinus (Geoffroy) dents known as the Muridae and to the order of tropical medicine." Macchiavello, 1954. Rodentia. The house mouse Mus musculus L. Anyone acquainted with world history is also belongs to this family. When these rodents aware of the devastating plague pandemics of are infected with Pasturella pestis, the disease the past, where millions of people died from its condition is known as murine plague. effects. In most cases these pandemics caused A great number of animals belonging to several other families of the order Rodentia a high rate of mortality, ranging from 60% to have been found to act as reservoirs of plague. 90%. The possibility of using natural vectors Such an infection in wild native rodents is in biological warfare to disseminate modern known as sylvatic plague. disease to a war-stricken population is frighten- Bubonic plague is the result of the infection ing to say the least. The very fact that plague by Pasturella pestis in the human organism. in both parasite and host has been identified Another classification of the disease is in Utah, has justified gathering as much data based on the location of the disease in a host's as possible on vectors and vector-host relation- body. This classification is used whether the ships. Each year new data are found, extending disease is in the definitive host, a rodent, or the the range of the disease from its originally dis- alternate host, man. covered focus in the U. S. at San Francisco in The common name reference to the disease 1900. Concommitant ^vith the geographic ex- by most people is that of bubonic plague. In pansion of the disease is the rapidly expanding this type of plague the usual portal of entrance population in Utah and the other western states. is the skin. Injection is accomplished by some This present study dealing with the distribution arthropod vector, usually a species of flea. of plague vectors, reservoir hosts and vector- Shortly after the entrance of the bacillus in a host relationships for the State of Utah should, host's body, a characteristic swelling occurs at therefore, prove valuable to the science of pre- the nearest l}TTiph node. This swelling of one ventive medicine. or more nodes produces what is known as a 16 Bricham Young University Science Bulletin bubo, from which the term "bubonic" plague in ancient history, religious, political or other- is derived. The enlargement of the nodes is wise, where pandemics and epidemics deci- due to the increased numbers of P. pestis being mated great populations of people, the exact formed at that locus, plus increased leucocyte etiological agent or agents are not known. It is activity. generally considered, however, by most writers In due process of time, an infected node on the subject today, that the earliest records of may become hemorrhagic and the bacilli will plague were perhaps a combination of disease find their way to the blood stream and are dis- epidemics due to several etiological agents. This tributed throughout the body to produce splee- was most likely the case of the great pandemics nic, hepatic, and other local infections. Such in Europe, Asia, and Africa during the sixth systemic distribution is identified as septicemic and fourteenth centuries which resulted in such plague. disastrous loss of life. In septicemic plague a local infection in any organ may be identified as hepatic plague, COSMOPOLIT.'^N OCCURRENCE OF PL.^iGUE spleenic plague, etc. One body part wliich is Historically speaking the most dramatic seriously affected is the lung area. Such an plague was that known as the "Black Death" infection have originated from a bubonic may which occurred during the 14th Century (1348- type or contracted directly from another organ- 49). The plague septicemia caused dark spots ism by way of the respiratory tract. This type to appear subcutaneously, hence the term "Black of infection is termed pneumonic plague. Death." Various figures have been given, but According to Kelly and Hite (1949), a conservative estimate of 25,000,000 persons "Bubos are present in about three-fourths of are supposed to have died of this disease at that the human cases. Septicemia with hemorr- time. In Oxford, England, it is said that two- hages into the skin and tissues is commonly thirds of those connected with educational in- present. The pneianonic variety is character- stitutions perished. The "Black Death" plague ized by pneumonia and the presence of or- of that period was supposed to have been Asiatic ganisms {P. pestis) in the sputum." in origin, first invading Nortli Africa and then the above three In the clinical diagnosis of Europe. kinds of disease, classified on the basis of lo- plague pandemic spread across cation in the body, several procedures are fol Another Europe and Africa during the sixteen hundreds. lowed. In the bubonic form, a bubo is aspirated Egypt lost approximately 1,000,000 of her in- and a smear is prepared and examined micro- habitants in 1603. The Great Plague of Lon- scopically for the bacilli. In addition to this, don, 1664-1665, caused a total of deaths for the the specimen is cultured in the laboratory, or year 1665 of 68, 596 in population estimated at some of the aspirated fluid is inoculated into a laboratory animal for further identification. 460,000. Blood cultures are obtained and produced from Meyer (1950) reports: specimen samples where septicemic plague is "In the Pacific Basin recent local epidemics the sputum suspected. In the pneumonic type warn that, although the plague problem is microscopically for the plague is examined solvable, it is not yet solved. In the post-war bacilli. period extensive outbreaks have been reported It must be re-emphasized that plague is from Java and China. According to incom- secondarily primarily a disease of rodents and plete information, during the first 42 weeks the effects are of man. In either case, however, of 1948 there were 3,422 cases in Java and is, the disease will symptomatically alike. That 3,365 persons died; in China in 1947 there septicemic, etc. produce buboes in either case, be were at least 30,000 cases. The old focus in infectious and fatal to As a disease it is just as BuiTna is still active, and in recent years Epi- rodents and other animals as it is to man. there have been a few cases of plague on the with rodent demiologically, to one acquainted island of Hawaii and in New Caledonia." surveys, it is clearly demonstrated from time The outstanding epidemic of the twentieth to time that plague epizootics have completely century although not as great as the "Black destroyed large colonies of animals. Death" was that which took place in Manchuria 1910-1911. More than sixty HISTORICAL RESUME during the years thousand persons lost their lives, the case fatal- EIarly historical records ity being almost 100% and was primarily of Regarding the many references to plague the pnemnonic type. Biological Series Vol. 1, No. 1, March, 1955 17

Burrows (1949) states: dent plague have been discovered in all of "During recent years, plague has caused terri- them except Colorado." ble loss of life in British India; official statis- The sylvatic plague studies by Ecke and tics show that in the period from 1896 to 1918 Johnson (1950) in Colorado showed extensive more than 10,000,000 deaths were due to this distribution of the disease among prarie dogs disease." and ground squirrels. The following quotation is taken from "Plague in Park County, Colorado, was first Hoekenga's (1947) article, "Plague in the discovered in the simimer of 1945, and spread Americas:" across the country through the prairie dog "During the period 1899-1939, approximately population in two years. In less than four 57,000 cases of human plague were reported years, it had killed practically all of the dogs from North and South America together. on about 627,000 acres." Some 2,500 more have been reported since V. B. Link, reporting in the September 30, 1950 then . . . Peru has the unhappy distinction of "Journal of the American Medical As- having had more plague (21,037 cases) than sociation," had the followdng to say about plague any other country." distribution in the Western United States: According to Simmons and Hays (1948): "Human plague attributable to contact with "Plague now exists in India, Ceylon, Burma, infected wild rodents was limited to Calif- Indochina, Java, China, Manchuria, parts of forina until 1934, when a human case was Asiatic Russia, Hawaii, Ecuador, Peru, Bo- reported in Lake County, Ore. Infected ro- livia, Argentina, Brazil, 14 western states of dents were found in Oregon in 1935 and the U. S., Canada, Germany, the Azores, successively in the following states: Mon- Madagascar, and many parts of Africa." tana, 1935; Idaho, 1936; Nevada, 1936; Utah, 1936; Wyoming, 1936; Washington, 1937; Plague in the western states of Arizona, 1938; New Mexico, 1938; Colorado, THE united states 1941; North Dakota, 1941; Oklahoma, 1944; C. R. Eskey and V. H. Haas (1940) of the Kansas, 1945; and Texas, 1946. Surveys United States Public Health Service published a have been conducted in over 600 counties of joint paper titled "Plague in the Western Part the 17 westernmost states, and plague has of the United States." Several quotations have been found nearly 4,000 times in the rodents been taken from their publication and are given of 132 cotmties of 15 of these states. South below. These references will show plague in- Dakota and Nebraska being the exceptions." cidence in the western United States up to the With regard to North America, Hubbard year 1940, as well as provide data on the ge- (1947) has this to say: ographic distribution of the disease to that date. "From its inception into man in North Ameri- Their observations include both sylvatic and ca in 1900, plague has been found in 506 bubonic records: persons, 321 of whom died of the infection. "In March, 1900, Dr. W. H. Kellog of San Eight states have reported human cases." Francisco, recognized the first human case Plague in Utah of plague reported in the United States. From In Allred's study 1900 to 1904 there were 121 cases with 113 (1952) of the distribution of some fleas to deaths reported at San Francisco, and during known be capable and potential vectors of plague in the second outbreak in 1904-08, there were Utah, he noted that plague had been recorded the followdng 160 cases with 78 deaths. Twelve cases were from eleven of the counties reported in Oakland, located across the bay twenty-nine of the state of Utah since the first discovery from San Francisco. In October, 1907, three in Beaver County in 1936: cases of human plague were discovered at County, July 1936 the port of Seattle." Beaver (Bubonic and Syl- vatic) "Due to the discovery of plague in Montana Sevier County, July in that year (1935)- three more units (U.S. 1936 Garfield County, August, 1936 P.H.S. mobile field survey units) were sent Morgan County, August, 1937 into the field in 1936." Salt Lake County, September, 1948 "Since the spring of 1935 field investigations Millard County, November, 1939 have been conducted in the 11 Pacific Coast Kane County, May, 1938 Rocky Mountain States and foci of wild ro- Rich Coimty, July, 1938 2 Plague of sylvatic nature was discovered by a U.S. P.H.S. unit in 1935 in the state of Montana. Wasatch County, August, 1937; June, 1938 18 Brigham Young University Science Bulletin

Weber County (No date given) the infection has become established among Iron County (No date given) wild rodents from the Pacific Mountains." "These characteristic epizootics, followed by PLAGUE AND ENDEMICITY subsidence of the disease into the enzootic state, when considered in the light of the logi- There are two schools of thought regarding cal inland progression of the infection among plague distribution. Meyer (1943),^ Meyer and the wild rodents, support the impression that Holdeni-ied (1949) for example maintain that plague is a disease with which they (the ro- plague be endemic from a distributional may dents) are in the process of acquiring the point of veiw; i.e., it exists and has existed in type of communal resistance which results various areas where it has been discovered the from longer contact with an infectious disease and has not necessarily been introduced from of this type." elsewhere. In the latter work, Meyer and Hol- "The establishment of plague among our wild denried studied a plague epidemic in California rodents is now so widespread, and has en- involving squirrels and non-native rats. From dured under so many different conditions of the summary of their publication the following climate and rodent ecology, that it must be quotations are given: regarded as peiinanent." "Xenopsylla cheopis was not found on the If the concept as given above in extract rats, but the relatively poor vector the mouse from the study by Eskey and Haas (1940) is flea (Leptosylla segnis), and a few Nosop- correct there may in part be some explanation sylla jasciatus were present. Rat fleas were why there are such conditions of pandemic not the squirrels. Thus it is not un- found on proportion in human infection, with occasional squirrel fleas not only intro- likely that the recurrence, resulting eventually in epidemic maintained the infection in duced, but also outbreaks and finally sporadic occurrences of the rat population." single cases. From the standpoint of biogeog- "These observations conclusively prove for raphy the distribution of plague has both en- the first time that plague may be spread demic and non-endemic aspects. wild to domestic rodents." from Even though rodents of the genera Citellus, Diuing the several years that the author Neotoma and Cynomys are considered the most has conducted plague vector surveys throughout general reservoirs of infection, several other Utah, there have been occasions when there was genera of rodents can maintain an infection observed what appeared to be epizootics of old reservoir. Such animals are the chipmunk and recent occurrence among rodent colonies. Eutamias sp., tree squirrel Tamiasciurus sp., In some of these examples the native rodent and marmot Marmota sp. colonies were far removed from contact with The condition of having plague infected rodents and their flea parasites. An domestic murine rodents come in contact with endemic of plague existing in localities far re- example rodents makes possible the establishment of a domestic rat contamination is de- moved from reservoir of sylvatic plague. The principal rea- scribed Eskey & Haas (1940, op. cit., 16). by p son of importance can be appreciated when "Trapping conducted on a routine basis yield- one realizes the close association between Rattus plague-infected fleas from a wood rat in ed rattus alexandrinus, Rattus rattus rattus, and County, Utah. In 16 nests of these ro- Kane R. norvegicus, man, and the flea vectors which dents which were demolished, 13 carcasses live with the rats and which readily bite man. were found, indicating an epizootic; no one Meyer and Holdenried (op. cit., 1949) in the vicinity had been aware of anything concluded that a murine infection may be de- unusual in regard to the wood rats." rived from on endemic infection. If such is the These authors in the same publication case, there is then created a serious situation. (page 19) have this to say regarding plague It is possible, to have a plague enzootic in native distribution in the western U. S.: rodents which will provide a reservoir of infec- "It has been pointed out under the discussion tion for murine hosts, or have an enzootic in of rodent epizootics that the spread of plague murine hosts which may act as a source of into inland regions of the continent has been infection for sylvatic rodents. In either case, a gradual and logical progression through a however, an epizootic of major or minor pro- period of nearly 40 years during which time portions, may break out. The greater the epi- "Clinical Parasitology." 3 C. F. Craig and E. C. Faust in their text. zootic among rodents the greater the chance page 81S, 1951, refer to Meyer (1!MJ) as follows: "supports the theory that wild rodent plague was present before the development for human infection either by direct contact of urban rodent plague in California." Biological Series Vol. 1, No. 1, March, 1955 19

with an infected animal or by vector transmis- discovered that some species of fleas are more sion, usually by a species of flea. In Utah, es- efficient vectors than others. This efficiency pecially in those areas where population den- seems to be associated with the rate of incuba- sity is greatest, there are found conditions of tion of the infective agent in the body of the flea distribution allowing for direct contact between which Eskey and Haas terms the "extrinsic ground squirrels and the Norway rats. Capable incubation of the infection" and which Sim- vectors for plague are found on both hosts and mons and Hays (1948, op. cit., p. 1679) say, interchange has certainly taken place. (Table "has been observed to range from 5 to 130 days. 1). This range exists among different species and even between different individuals of at least PLAGUE AND PLAGUE VECTORS two species. A', jaciatus and Opisocrostis labis." Xenopsylla cheopis is the most common Many species of fleas have been shown and efficient vector of plague where plague of to be vectors of plague. Lice and ticks are also bubonic nature is considered as endemic, such known to demonstrate plague experimentally as in India (flea sometimes termed "Indian rat but are of no importance as far as our field flea" as well as the "Oriental rat flea") parts of surveys have revealed. Africa, South America, North America, and The most usual process of plague trans- the U. S. It readily bites man and can be ex- mission by the flea is in the main the result pected to be found wherever domestic rats have of what is known as a "blocked" condition. A become distributed although this is not a hard blood meal from an infected host is taken up and fast rule. For example, X. cheopis has been by a flea and passed along the esophagus to the but rarely found in Utah as far as present col- proventriculus. This structure is an enlarged lection records show, even though domestic rats bulbous part of the alimentary canal just an- are widely distributed in the north-central part terior to the stomach. The peculiarity in struct- of the state. ure of the proventriculus allows the plague ba- Simmons and Hays (1948, op. cit., p. 1680) cillus in the blood to multiply and increase in say: numbers sufficient to "block" off the passage of the blood to the stomach. In many cases the "It seems probable that human (bubonic) blocking may occur in the stomach region. The plague may be perpetuated by Pulex irritans Linnaeus, without intervention of rats. flea, unable to get sustenance from its blood Such meal feeds again, perhaps from an infected host a mode of spread may have been active in or another host free from plague. In the pro- the Black Death and the great plague of cess of feeding, due to an already filled esopha- London." gus and proventriculus or stomach, it may re- Craig et. al., (1951, op. cit., p. 816) in re- giirgitate its previous meal plus plague bacilli ferring to studies made by Eskey say: and a reinfection or new infection results. "On epidemiological grounds, Eskey (1930) believes that irritans is re- It is well known that some species of fleas Pulex probably are more efficient vectors of plague than otliers. sponsible for most of the human cases of in the high mountain districts of For example, Eskey and Haas (1940, op. cit. plague Ecuador, where X. cheopis does not occur, p. 42) in their laboratory tests found that Oro- psylla idahoensis (Baker) and Malareus telchin- although in Guayaquil the latter is the only um (Roth) were poor vectors and stated that flea apparently responsible for epidemic out- in the case of M. telchinum, "these fleas could breaks in human population (Eskey 1938)." not be natural vectors of the infection." On the Quoting further from Simmons and Hays other hand, the rat fleas Xenopsyla cheopis (1948, op. cit, p. 1678): (Roth) and Nosopsyllus fasciatus (Bosc d'An- "Diamanus montanus and HoplopsyUus ano- tic) were demonstrated experimentally to be malus (are considered important as actual equally effective as vectors of plague. The gene- and potential vectors of plague) in the west- ral conclusion reached by Eskey and Haas in em part of the United States; Nosopsyllus laboratory tests was: "That some of the wild silantievi and A', tesquoruni in Mongolia; rodent fleas are as capable vectors as either of Rhopalopsyllus cavicola in Argentina and the rat fleas." Ecuador; X. erides, DinapsyUus lypusus and In the examples given above, reference Chiastopsyllus rossi in South Africa; X. bra- has been directed to laboratory experiments on siliensis in Uganda, Kenya and Nigeria (Afri- disease transmission. When attention is di- ca); and Pulex irritans in many parts of the rected to natural transmission, it is likewise world." 20 Brigham Young University Science Bulletin

Vi o s2

-a h -S ^ S £ ^ S E .!2 2 3 g -2 P I

"" rt o -S c -3 g 3 B -a g S .2 3 S o -s; « 2 S- Biological Series Vol. 1, No. 1, March, 1955 21

a o W S e 3 DJ i5 -3 S .& = «

^ -S -2 « s ^ S £ .2 -a 5 § g .2 p w 3 •" S « o -5, .S g £ -G 3 .2 3 £ O

S 2 1 ^ ^ = ^ ^ £ S 5 -2 -2 -2 ^ «

< y p- S e- i? 2 22 Brigham Young University Science Bulletin

Seasonal variations in vector populations Taxidea taxus neglecta (Mearns), the An understanding of plague vector re- badger of the western U. S., is a carnivore lationships involves the matter of seasonal vari- which, however, has been shown to act as a ations, with special reference to populations. resei-voir for the plague organism. That there is seasonal variation of this type, in Reservoir hosts of plague in Utah rodent infestation by fleas, is well known for This particular subject will be discussed certain species. Both Eskey and Haas (1940), under two headings: and Holdenried, Evans and Longanecker (1951) 1. Those species of animals in showed this to be true with Diamanus montanus Utah which have been found infected with (Baker) and Hoplopsyllus anomalus (Baker). the plague organism P. pestis. These two species of fleas are capable vectors 2. Those species of animals in Utah which of plague. Holdenried, et al, showed H. ano- have been found to be plague positive in malus to be abundant from October through other states but although March, while Diamanus montanus was most distributed in Utah, have not as yet been found to harbor abmidant in other months with a low density plague the organism. of population in the springtime. These authors The first discovery of plague in Utah was worked with Citellus beechyi douglasii (Rich- made in July, 1936, (Public Health Reports, ardson), the common California ground squir- Vol. 51, p. 1138). Since that time, through rel. This squirrel is one of the common host surveys by the U. S. Public Health Service, reservoirs of the plague organism in California. thirteen of the twenty-nine counties in Utah In some aspectional field studies with Anomiop- have had some plague incidence indicated. Un- syllus amphibolus Wagner, a consors of Neo- doubtedly an intensified state-wide bacterio- toma lepida Thomas, conducted as a part of logical sui-vey would greatly extend the inci- these investigations, there were found distinct dence. Dr. D. M. Allred, (1952) a former population changes during a 12-month period. associate in these investigations, has listed in- RESERVOIR HOSTS AND formation on plague discoveries in Utah from PLAGUE VECTORS 1936 to and including 1949, as follows: Beaver County: Citellus variegatus, July and The following taxonomic orders of mam- August, 1936; Marmota flaviventer, July mals are listed in order of importance as reser- 1936. voir hosts for plague: Rodentia, Lagomorpha, Sevier County: Citellus variegatus, July, and Carnivora. The genera and species of ani 1936; C. armatus. May, 1949. mal reservoirs found in these orders differ when Garfield County; Cynomys parvidens, Aug- analyzed on a world-wide basis. For example, ust, 1936. the squirrel genus Citellus repi'esented by seve- Morgan County: Citellus variegatus, August, ral species, is the most important sylvatic genus 1937. which acts as a reservoir host for plague in the Kane County: Neotoma lepida. May, 1938. western United States. In South Africa, Davis Rich County: Citellus armatus, July, 1938. (1948) reports that the primary rodent reser- Wasatch County: C. armatus, August, 1937 voir of a sylvatic nature are the gerbils of the and June, 1938. genus Tatera, represented by several species. Salt Lake County: C. variegatus, Sept., 1948 The order Rodentia includes both "Murine" and March, 1949; Peromyscus manicula- and "Sylvatic" plague host reservoir animals. tus, Sept., 1948. The murine reservoir includes those species and Millard Covmty: In late November or early genera of hosts belonging to the family Muridae December of 1939, a man supposedly con- and represented prominently by domestic rats, tacted plague from skinning a coyote. house or ship rats Rattus r. rattus, Norway or (From conversation with residents who re- sewer rats Rattus nvrvegicus, Alexandrine rat member the case, the writer has strong Rattus r. alexandrinus and the house mouse reason to believe that the man had some Mus musculus. other disease contracted from some other The order Lagomorpha includes rabbits source.) and hares represented by such genera as Syl- Weber and Iron Counties: The Communi- vilagus and Lepus. Their several species act as cable Disease Center Bulletin (1948) lists reservoir hosts for plague. plague as having occurred in these coun- The Carnivora apparently rarely serve as ties, but gives no specific date, host, or host reservoirs for plague. locality. Biological Series Vol. 1, No. 1, March, 1955 23

Grand and San Juan Counties: During 1949, C. beecheyi beecheyi (Richardson) a hyper-epizootic occurred among prairie C. beecheyi douglasii (Richardson) dog colonies in these counties. However, C. beecheyi fisheri (Merriam) no evidence was found to indicate sylvatic C. beecheyi nudipes Huey plague as the cause of the decrease in population. C. beldingi oregonus (Merriam) At one time in southern and western Utah C. columbinus columbianus (Ord) County there where great numbers of Citellus C. columbianus ruficaudus Howell townsendi mollis, the Townsend ground squir- C. idahoensis Merriam rel. This likewise true of other areas in the was C. lateralis chrysodeirus (Merriam) Great Basin of Utah. Now there are only C. mexicanus parvidens (Mearns) scattered colonies with very little continuity C. richardsonii elegans (Kennicott) of distribution. Colonies in Utah County are C. richardsonii nevadensis Howell practically non-e.xistent. As observed by the C. richardsonii richardsoni (Sabine) writer, from 1921-28, the ground squin-el Citel- C. spilosoma major (Merriam) lus armatus was continuous in distribution C. townsendii mollis (Kennicott) throughout the Marsh Valley, and the Portneuf C. tridecemlineatus ssp. River areas between McCammon and Lava Hot C. variegatus grammurus (Say) Springs in Bannock County, Idaho. According C. variegatus Utah Merriam to the testimony of residents who have lived in C. washingtoni loringi Howell those areas all their lives, from 1940 to 1946 C. washingtoni washingtoni Howell ground squirrels became practically extinct. Of Cynoniys gunnisoni gunnisoiii (Baird) late years they are beginning to increase but C. gunnisoni zuniensis HoUister are still not common. On inquiry in August C. leucurus (Merriam) 1954 in Bannock County, I was informed that C. ludovicianus arizonensis Mearns now and again a ground sqiurrel {Citellus arm- C. parvidens Allen atus)is seen. This information was given from Dipodomys ordii ordii Woodhouse specific localities where, as a youth (1920-25) Eutamias quadrivittatus frater (Allen) the writer was involved in poisoning programs E. minimus ssp. where thousands of specimens were killed. Glaucomys sabrinus lascivus (Bangs) decimation of whole ro- Almost complete Lagurus curtatus ssp. a single season has dent populations during Lepus californicus ssp. been commonly met with during the present Marmota flaviventer avara (Bangs) survey. In fact the disappearance of once M. flaviventer engelhardti (Allen) abundant rodent populations had been too con- M. flaviventer flaviventer (Audubon & Back- sistent to be a happenstance. These extreme man) fluctuations in rodent populations may be due M. flaviventer nosophora Howell interference environment- in part to man's with Microtus californicus ssp. or it is a reflection of the al conditions, perhaps M. nanus ssp. populations noted in some inherent rhythm M. montanus ssp. animals. M. townsendii (Bachman) It is also possible that the almost; and, in Mus musculus ssp. some cases, complete disappearance is due to a Mustela sp. disease agent and the vectors involved. Ecke Neotoma albigula ssp. and Johnson (1950) found that the disease A^. cinerea occidentalis (Baird) plague, contributed to a practical elimination of A', fuscipes mohavensis Elliot all prairie dogs over an area of 627,000 acres A^. lepida intermedia (?) in Park County, Colorado. A', lepida lepida Thomas An examination of the literature from A^. micropus ssp. many sources, especially the Public Health Re- Onychomys leucogaster ssp. ports, reveal that there are sixty-eight species O. torridus ssp. and subspecies of plague implicated mammals Oryzomys sp. occurring in the western United States in which Perognathus sp. the plague organism has been found. They are Peromyscus boylii ssp. shown below: P. leucopus ssp. Citellus armatus (Kennicott) P. maniculatus ssp. 24 Brigham Young University Science Bulletin

P. truei gilberti Allen Sylvilagus auduboni ssp. P. truei truei (Schufeldt) S. nuttallii nuttallii (Bachman) Rattus norvegicus (Erxleben) Taxidea taxus ssp. R. rattus alexandrinus (Geoffroy) Thomomys talpoides ssp. R. rattus rattus (Linnaeus) R. rattus alexandrinus (Geoffroy) Reithrodontomys megalotis ssp. See Table 5 for a listing of plague vector Sigmodon hispidus ssp. implications with reference to distribution. Sylvilagus auduboni ssp. S. bachmani ssp. Fleas as pl.\gue vectors in Utah S. nuttallii nuttallii (Bachman) According to Simmons and Ilays (1948, Tamiasciurus douglasii albolimbatus (Allen) op. cit., p. 1678), "Thirty-nine American fleas Taxidea taxus neglecta (Mearns) have been shown infectable with plague in the Thomornys talpoides ssp. laboratory, and twenty-eight are cipable vec- Of the above listed species and subspecies tors." This agrees closely wdth the figure of there are forty-one species and subspecies of Allred (1952, op. cit., p. 67), in which he men- these plague implicated mammals represented tions, "Various workers have implicated more in Utah. This list is given below: than sixty species and subspecies of fleas with Citellus armatus (Kennicott) human and sylvatic plague throughout the C. beldingi ssp. world. Of this number, over forty-five species C. lateralis ssp. and subspecies are known to occur in the U. S." C. richardsonii elegans (Kennicott) During the last three years while the C. spilosoma major (Merriam) plague- vector-host distribution studies have been C. townsendii mollis (Kennicott) in progress in Utah, a total of 78 species and C. tridecemlineatus ssp. subspecies of fleas have been collected. Of this C. variegatus grammurus (Say) number there are represented in Utah 32 spe- C. variegatus Utah Merriam cies and subspecies which are known to be Cynomys gunnisoni zuniensis Hollister plague implicated. This plague implication is C. leucurus Merriam of two types, potential" or capable' with regard C. parvidens Allen to vector relationship. Dipodomys ordii ordii Woodhouse Eutamias quadrivittatus ssp. Fleas and murine plague in Utah E. minimus ssp. Glaucomys sabrinus ssp. Fleas show a certain specificity in host Lagurus curtatus ssp. preference even though there is a definite inter- Lepus californicus ssp. change of parasites at times. The degree of in- Marmota flaviventer engelhardti (Allen) terchange is greatly affected by the factor of M. flaviventer flaviventer (Audubon & Bach- proximity of association the different species of man)^ fleas have geographically, the population dens- Microtus montanus ssp. ity of each species of flea involved, the geo- Mus musculus ssp. graphical distribution of the host animal, as Mustela sp. well as seasonal and climatic factors affecting Neotoma albigula ssp. both host and vector. N. cinerea ssp. Xenopsylla cheopis is usually considered A', lepida lepida Thomas to be associated with domestic rats. However, Onychomys leucogaster ssp. in Utah this species has been taken but rarely O. torridus ssp. and then only from Rattus rattus alexandrinus Perognathus sp. in Salt Lake City. On the other hand, the rat Peromyscus boylii ssp. flea Nosopsyllus fasciatus (Bosc.) has been ta- P. maniculatus ssp. ken in most instances where the Norway rat P. truei ssp. Rattus r. norvegicus has been cx)llected in Utah. P. truei truei (Schufeldt) The limiting factors in the distribution of Rattus norvegicus (Erxleben) the Noi-way rat, R. rattus norvegicus in Utah R. rattus rattus (Linnaeus) are not known. The general area of location at ssp. Reithrodontomys megalotis 6 A potential vector is one which demonstrates the presence of the etiological agent in its body but has not been found to transmit 5 This species is most liltely A/. /. nosophora Howell, as A/. /, jlavi- the disease organism either experimentally or naturally. venter is restricted to Sierra Nevada in the vicinity of Lake Ta- 7 A capable vector shows the presence of the disease in the body o( ability disease hoe, M. /. nosophora is widely distributed in mountainous areas the vector and has demonstrated the to transmit the of the northern half of Utah. either experimentally or naturally. Biological Series Vol. 1, No. 1, March, 1955 25

present is along the base of the Wasatch range potential vectors of plague in Utah, twenty spe- of the mountains from Santaquin, Utah north cies would be considered as capable and eleven to the Utah-Idaho border. They have been re- as potential vectors associated with sylvatic ported from widely scattered areas in Sevier, hosts. The names of the species of fleas known Juab and Duchesne counties. I'heir greatest as consortes of sylvatic hosts are shown below concentrations are in Utah, Salt Lake, Weber, under the two categories of potential and capa- and Cache counties where human population ble vectors. Xenopsylla cheopis is the only is also most dense. exception. (See Tables 1 and 5 for the vector That Xenopsylla cheopis and Nosopsyllus host relationships as well as distribution by fasciatus are efficient vectors of plague is well county). known. The flea Diamanus rnontanus is usually considered to be a ground squirrel consors, but POTENTIAL VECTORS it has also been taken from domestic rats in 1. Catallagia decipiens Rothschild Utah thus creating a possible bridge between 2. Epitedia wenmanni (Rothchild) sylvatic and murine reservoirs. D. rnontanus is 3. Foxella ignota ssp. an efficient vector of plague in its own right. 4. Hoplopsyllus affinis (Baker) Other fleas associated with the domestic rats 5. Megarthroglossus divisus divisus (Baker) in Utah, and which are plague implicated are, 6. Monopsyllus wagneri wagneri (Baker) Monopsyllus wagneri wagneri (Baker), Epi- 7. Neopsylla inopina Rothschild tedia wennianni (Rotli), and Megabothris aban- 8. Opiscrostis tuberculatus cynomuris Jelli- tis (Roth). Mus musculus, the house mouse, son another murine rodent, is also associated with 9. Orchopeas sexdentatus agilis (Rothschild) Nosopsyllus fasciatus and Epitedia wennianni 10. Orchopeas sexdentatus nevadensis (Jor- in the Utah collections. The house mouse, Mus dan) musculus, unlike the Norway rat does not seem 11. Thrassis petiolatus (Baker) to be restricted in its geographic distribution, is in or aroimd most places of human but found CAPABLE VECTORS habitation. It is generally found by most workers that the house mouse carries very few 1. Atyphloceras multidentatus (C. Fox) fleas. This has been our experience during the 2. Ctenocephalides felis felis (Bouche) period this research project has been operating. 3. Diamanus montanus (Baker) Many specimens of the house mouse, M. mus- 4. Echidnophaga gallinacea (Westwood) culus, were collected without producing a single 5. Hoplopsyllus anomalus (Baker) flea of any species. The house mouse usually 6. Hystrichopsylla gigas dippiei Rothchild has as its flea consortes, when such are present, 7. Malaraeus telchinum (Rothchild) those species which are found most commonly 8. Megabothris abantis (Rothchild) on other species of hosts in the immediate en- 9. Monopsyllus eumolpi eumolpi (Roths- virons. The flea Histrichopsylla gigas dippiei child) Rothschild, itself a capable vector of plague, 10. Nosopsyllus fasciatus (Rose) has been found associated wdth Mus musculus 11. Opisocrostis hirsutus (Baker) in a few of our collections. 12 Opisocrostis labis (Jordan and Roths- From the standpoint of vector relationship child) D. montanus, M. abantis, N. fasciatus, X. che- 13. Opisocrostis tuberculatus tuberculatus opis and Histrichopsylla gigas dippiei are capa- (Baker) ble vectors, while E. wenmanni and M. wagneri 14. Oropsylla idahoensis (Baker) wagneri are potential vectors of plague. (See 15. Pulex irritans Linnaeus

Tables 1, 2, 3 and 4 for host parasite relation- 16. Thrassis arizonensis arizonensis (Baker) ship as well as patterns of distribution for each.) 17. Thrassis francisi (C. Fox) Fleas and Sylvatic plague in Utah 18. Thrassis howelli howelli (Jordan)

With the exception of X. cheopis, all spe- 19. Thrassis pandorae Jellison cies of fleas listed above and found associated 20. Xenopsylla cheopis (Rothschild) with murine hosts in Utah, are also found on Capable vectors sylvatic hosts which have been implicated with With reference to the capable vectors, the plague. 8 Allred (1952) listed Thrassis acamantis (Rothschild) as one of the Of the thirty-one'^ species and subspecies Utah fleas. This species is plague implicated but does not occur in of fleas listed Allred capable Utah, being confused with both Thrassis slanfordi and T. howelli by (1952) as and utahensis in its distribution. 26 Brigham Young University Science Bulletin

HOST ANIMAL SPECIES Biological Series Vol. 1, No. 1, March, 1955 27

OT o

HOST ANIMAL SPECIES 28 Brigham Young University Science Bulletin

5 .2 ^ o. m 29 Biological Series Vol. 1, No. 1, March, 1955

COUNTY NAMES 30 Brigpiam Young University Science Bulletin

PLAGUE IMPLICATED HOSTS

C= capable vector

P= potential vector

COUNTY NAMES Biological Series Vol. 1, No. 1, March, 1955 31

PLAGUE IMPLICATED HOSTS

C = capable vector

P = potential vector

COUNTY NAMES .

32 Brigham Young University Science Bulletin

most widely distributed species in Utah are D. Several species other than the 3 species of montanus, Hoplopsyllus anomalus, Malaraeus Cynomys have been shown to be hosts for this telchinum, Oropsylla idaboensis, Thrassis pan- species of flea in Utah (Table 1). dorae, and Monopsyllus eurnolpi eumolpi. The list of fleas shown below is arranged There are undoubtedly other factors involved, in order of relative abundance in Utah as de- but tliis wide distribution is in part due to termined in the main from collections made the extensive distribution of the hosts involved by this survey. For an illustration showing the for each species of flea, as well as to the ability pattern of distribution in Utah see Fig. 14. of the above-named fleas to adapt to several 1. Diamanus montanus hosts, although they may be more commonly 2. Hoplopsyllus anomalus associated with certain species or genera of 3. Thrassis pandorae hosts. For example, the flea Diamanus mon- 4. Oropsylla idahoensis tanus is found on at least 27 species and sub- 5. Opisocrostis hirsutus species of mammals in Utah representing 12 6. Malaraeus telchinum genera other than Citellus. However, it is usual- 7. Thrassis howelli howelli ly listed in the literature as a squirrel flea, es- 8. Echidnophaga gallinacae pecially for the squirrels Citellus armatus and 9. Nosopsyllus fasciatus Citellus variegatus. This condition of relative 10. Monopsyllus eumolpi eumolpi host specificity is likewise the case for the fleas 1 1 Opisocrostis labis Hoplopsyllus anomalus, Oropsylla idahoensis 12. Megabothris abantis and Thrassis pandorae, although their host ran- 13. Atyphloceras multidentatus ges are not so extensive as D. montanus. The 14. Opisocrostis tuberculatus usual hosts of Malaraeus telchinum as found in 15. Ctenocephalides felis felis Utah are various species of native mice, al- 16. Pulex irritans though it has been found on field mice and 17. Histrichopsylla gigas dippiei pack rats. M. eumolpi eumolpi is regarded as 18. Thrassis francisi a chipmunk flea. Records from the literature 19. Thrassis arizonensis and our field studies show it to be associated 20. Xenopsylla cheopis with eight other genera and 11 species of ro- Eskey and Haas (1940, op. cit., p. 41) ex- dents in addition to 3 species of chipmunks in perimentally demonstrated the possibilities of the genus Entamias. This would constitute a transmission of plague by several species of total of fourteen species and subspecies acting fleas. The effectiveness of transmission varied. as hosts for this particular flea (Table 1). Comparing his list of species with the plague- There are certain capable vectors which implicated capable vectors found in Utah, the following list of Utah fleas are arranged below are fairly abundant (that is, the numbers found in order of their apparent effectiveness as trans- on a given species of host is high) and common mitters. The pattern of distribution is shown in (that is, at least a few specimens are usually found on most of the hosts collected) but are re- Fig. 13. stricted geographically. This is true of the flea 1. Xenopsylla cheopis Echidnophaga gallinacea. This flea is apparent- 2. Nosopsyllus fasciatus ly restricted to the southern portion of the State 3. Hoplopsyllus anomalus in Utah. One of its more common hosts is the 4. Diamanus montanus squirrel Citellus variegatus which as a host ani- 5. Thrassis pandorae mal has a very extended distribution over the 6. Opisocrostis tuberculatus State. Another host to this flea, having wide 7. Opisocrostis labis geographic distribution within the State,, is The generalized pattern of distribution by Citellus leucurus and its several subspecies. county, for the above-listed fleas in Utah, as Nevertheless, for some unknown reason the well as all other capable vectors, is shown in flea parasite E. gallinacea does not follow the Table 3. same distributional pattern as its host. (Table

1 and Fig. 14). Potential Vectors

Opisocrastis hirsutus, whose usual hosts are There are several species of fleas involved considered to be the several species of prairie as potential vectors for plague in Utah. One dogs widely distributed in Utah, is restricted species, Monopsyllus wagneri wagncri, far sur- in the sense that its range is determined some- passes all others in its geographic distribution. what by the extent of prairie dog distribution. It is a native mouse flea but has a rather general Biological Series Vol. 1, No. 1, March, 1955 33

DAHO

ARIZONA

Fig. 13. Distributional pattern for those species of fleas in Utah listed as the most effective capable vectors for plague. 34 Brigham Young University Science Bulletin

IDAHO

114 113 112 III 42 UTAH

BOX ELDER 41 41

TOOELE 40- 40 O O< O 5 US O> O 39 39

38 38

37 3T

ARIZONA

Fig. 14. Map showing the general distributional pattern for fleas listed as capable vectors for plague. Biological Series Vol. 1, No. 1, March, 1955 35

host habitat adaptation. It is found on thirty- which plague-implicated vectors have been four species and subspecies of mammals in taken. Utah including the four species of Peromyscus, 3. As a result of these studies it has been which constitute its usual host. Another widely found that there are thirty-one species and distributed potential vector is Orchopeas sex- subspecies of fleas occuring in Utah as dentatus with agilis two subspecies and nevaden- plague-implicated vectors. They are classi- sis. Whereas M. w wagneri has rather broad fied as being capable (natural) and po- host tolerance, Orchopeas sexdentatus agilis and tential (experimental) vectors. Twenty nevadensis seem to be mainly relegated to wood- species are listed as capable and eleven as rats and native mice. Epitedia wenmanni an- potential vectors. other mouse flea, listed as a potential vector of 4. Both capable and potential vectors have plague, has a fairly wide geographic distribu- wide geographic distribution and variable tion. It is unusual, however, to find more than host adaptations. For example, Diamanus two or three specimens on a single host. Other rnontanus, a very efficient vector for plague, than Peromyscus inaniculatus the primary host, occurs on twenty genera other than the ge- this species of flea has been taken from field nus Citellus in Utah. It is commonly listed mice Microtus rnontanus, the wood rat Neo- as a squirrel flea, but it is found on at least toma lepida, the kangaroo rat, Dipodomys ordii. eighteen species of mammals other than Vector distribution pattern for the potential members of the squirrel genus as far as vectors is showTi in Table 4. This table shows Utah is concerned. only the geographic location by counties as 5. Every Utah county has one or more space does not permit listing by smaller geo- capable plague-implicated vectors present. graphic or political subdivisions. Efficient plague-implicated vectors of seve- SUMMARY AND CONCLUSIONS ral species, and plague-implicated hosts, are found to be densely distributed where hu- Through the courtesy of the National In- man populations are most highly concen- stitutes of Health, Grants and Fellowships Di- trated in the state. vision, a project was established at Brigham Young University to study the distribution and LITERATURE CITED host relationships of vectors for Rocky Moun- tain spotted fever and plague in the state of Allred, D. M., 1952. Plague important fleas Utah. This summary has reference only to the and mammals in Utah and the Western latter as the two divisions of the project are United States. The Great Basin Naturalist discussed under separate sections. Nevertheless 12; (4) 67-75. it was felt necessary to discuss some subjects Augustson, G. F., 1943. Preliminary records common to both in the first division of this re- and discussion of some species of Siphon- port. This includes the statement of pui'pose apteria from the Pacific Southwest. Bulle- and scope of the project, a generalized descript- tin Southern California Academy of Sci- tion of the physiographic features of the state of ence 42: 69.

as it affected Utah the problems at hand, and , 1944. The Flea genus Thrassis and syl- techniques involved in obtaining data. With vatic plague, with a description of T. bren- strict reference to the problem of vector and nani. Journal of Parasitology 30 (4): 237- host relationship the following conclusions may 240. be drawn regarding plague-vector distribution. Baker, Carl F., 104. A revision of American 1. Plague as a disease in Utah does exist. Siphonaptera, or fleas, together with a It has been known to be present since 1936 complete list and bibliography of the group. and since that time the disease has been Proceedings of the U. S. National Museum identified in thirteen of the twenty-nine 27: 365-469. counties of the state. Beck, D Elden, 1953. A study of some consortes 2. Of the sixty-eight species and subspecies at a nesting site of the Northern Cliff Swal- of plague-implicated mammals in the west- low Petrochelidon albifrons albifrons (Ra- em United States, forty-one species and finesque). Proceedings of the Utah Acade- subspecies are represented in Utah. There my of Sciences, Arts and Letters 30: 39-42.

is not a single county wdthout one or more , Bamum, A. H. and Moore, L., 1953. plague-implicated mammal species being Arthropod consortes found in the nests of present and widely distributed, and from Neotoma cinerea acraia (Ord) and Neo- 36 Brigham Young University Science Bulletin

toma lepida lepida Thomas. Proceedings Health Bulletin 254: 1-83. of the Utah Academy of Sciences, Arts and Ewing, H. E. and Fox, Ii-ving, 1943. The fleas Letters 30:43-52. of North America. United States Depart- Bishopp, F. C, 1915. Fleas. United States De- ment of Agriculture, Miscellaneous Publi- partment of Agriculture Bulletin No. 248: cation 500: 1-142. 1-31. Fautin, Reed W., 1946. Biotic communities of

Brown, J. H., 1944. The fleas (Siphonaptera) the Northwestern Desert Shrub biome in of Alberta, with a list of the known vectors Western Utah. Ecological Monographs 16: of sylvatic plague. Annals of the Ento- 251-310. mological Society of America 37 (2): 207- Fox, Irving, 1940. Fleas of Eastern United 213. States, Iowa State College Press, Ames, Burroughs, A. L., 1944. The flea Malaraeus Iowa. telchinum a vector of P. pestis. Proceed- Hampton, B. C, 1940. Plague in the United ings of the Society for Experimental Bi- States. Public Health Reports 55 (26): ology and Medicine 55: 10-11. 1143-1158.

, 1947. The vector efficiency of nine spe- , 1945. Plague infections reported in the cies of fleas compared with Xenopsylla United States during 1944 and summary cheopis. Journal of Hygiene 45 (3): 371- of human cases, 1900-1944. Public Health 396. Reports 60 (46): 1361-1365. Burrows, William et al., 1949. Jordan-Burrows Hoekenga, M. T., 1947. Plague in the Ameri- Textbook of Bacteriology, 15th Ed. 502- cas. The Journal of Tropical Medicine and 510. W. B. Saunders Co., Philadelphia, Hygiene 50 (10): 190-201. Pennsylvania. Holdenried, R., Evans F. C. and Longaneker, Byington, L. B., 1940. Two epizootics of plague D. S., 1951. Host- parasite-disease relation- infection in wild rodents in the western ships in a mammalian community in the United States in 1938. Public Health Be- central coast range of California. Ecologi- ports 55 (33): 1496-1501. cal Monographs 21 (1): 1-18. Costa Lima, A. Da and Hathaway, C. R., 1946. Holland, George P., 1949. The Siphonaptera Bibliografia, catologo e animais per elas of Canada. Publication 817. Techincal sugados. Monografias do Instituto (4) Os- Bulletin (70) Dominion of Canada. De- waldo Cruz, Brazil. partment of Agriculture, Ottawa, Canada.

Craig, C. F., Faust, C. E. and Miller, A., 1951. Hubbard, Clarence Andresen, 1947. Fleas of Clinical Parasitalogy. p. 811, Lea and Febi- Western North America. Iowa State Col- ger Publishers, Philadelphia, Pennsylvania. lege Press, Ames, Iowa.

Davis, D. H. S., 1948. Sylvatic plague in South Humphreys, F. A. and Campbell, A. G., 1947. Africa: History of plague in man, 1919- Plague, Rocky Mountain spotted fever, and Canada. Canadian 1943. Annals of Tropical Medicine and Para- Tularemia surveys in Health 38: 124-130. sitology 42 (2): 207-217. Journal of Pubhc Durrant, Stephen D., 1952. Mammals of Utah. Jellison, W. L., 1938. The possible role of birds University of Kansas Publications, Mu- in the epidemiology of sylvatic plague. seum of Natural Histoiy. University of Journal of Parasitology 24: p. 12. Kansas, Lawrence, Kansas, 6: 1-549. — 1947. Siphonaptera: Host distribution of Ecke, D. H. and Johnson, C. W., 1950. Sylvatic the genus Opisocrostis Jordan. Transac- plague in Park County, Colorado. Trans- tions of The American Microscopical So- actions 14th North American Wildlife Con- ciety. 46(1): 64-69. 7. 9: 191-197. ference, March 6, ; Locker, Betty, and Bacon, Roma Fullberg. and Johnson, C. W., 1952. Plague in Colo- Index to the literature of Siphonaptera of rado. Public Health Monograph, Pt. 1: North America Supplement (1): 1939- 1-37, U. S. Government Printing Office. 1950. Rocky Mountain Laboratory, Hamil- Eskey, C. R., 1938. Recent developments in our ton, Montana. knowledge of plague transmission. Public and Good, Newell E., 1942. Index to the Health Reports 53 (2): 49-57. literature of Siphonaptera of North Ameri- Health Bulletin and Haas, V. H., 1940. Plague in the ca. National Institutes of western part of the United States. Public 178: 1-193. Biological Series Vol. 1, No. 1, March, 1955 37

KeUy, F. C. and Hite, E. K., 1949. Microbi- Rothschild, Miriam and Clay, Theresa, 1952. ology, pp. 399-401. Appleton-Century Fleas, Flukes and Cuckoos. The Philoso- Crofts, New York., N. Y. phical Library Inc., 15 East 40th Street, Kohls, Glen M., 1939. Siphonaptera: Notes on New York 16, New York. synonymy of North American species of Rucker, W. C, 1915. Plague: Its geographic the genus Hoplopsyllus Baker. Public distribution and its menace to the United Health Reports 54 (s.): 2019-2023. States. Public Health Reports 30 (19): 1428-1431. , 1940. Siphonaptera—A study of the species infesting wild hares and rabbits of Simmons, S. W. and Hays, W. J., 1948. Fleas North America north of Mexico. National and disease. The Proceedings of the Fourth Institutes of Health Bulletin 175: 1-34. International Congress on Tropical Medi- Link, V. B., 1950. Plague. The Journal of the cine and Malaria pp. 1678-1688. American Medical Association 144 (5): Snodgrass, R. E., 1946. The skeletal anatomy 375-377. of fleas (Siphonaptera). Smithsonian Mis- cellaneous Collections 104 1-89. , 1950. Plague epizootic in Cottontail Rab- (18): bits. Pubhc Health Reports 65 (21): 696. Stanford, J. S., 1931. A preliminary list of Utah Macchiavello, Atilio, 1954. Reservoirs and Vec- Siphonaptera. Proceedings of Utah Acade- tors of Plague. Journal of Tropical Medi- my of Science 8: 153-154.

cine and Hygiene 57: 3-8, 45-48. , 1944. More Utah Siphonaptera. Proceed- Merriam, C. H., 1898. Life zones and crop ings of Utah Academy of Sciences, Arts zones of the United States. U. S. Depart- and Letters 19: 173-178. ment of Agriculture Division Biological Stark, H. E., 1948. A Preliminary study of Utah Survey Bulletin Number 10: 1-79. fleas. Unpublished Master of Science Thesis, University of Utah. Meyer, K. F., 1950. Modem therapy of plague. The Journal of the American Medical As- Stewart, M. A. and Evans, F. C, 1941. A com- sociation 144 (12): 982-985. parative study of rodent and burrow flea populations. Proceedings of Society for and Holdenreid, R., 1949. Rodents and Experimental Biology and Medicine 47: fleas in a plague epizooitic in a rural area 140-142. of California. The Puerto Rico Journal of Survey of the recreational Public Health and Tropical Medicine 24 resources of the Colo- rado River Basin. 1950. United States (3): 201-209. Department of the Interior Publication. Miles, Virgil L; Maxwell, J. Jr. Wilcomb, and Compiled in 1946. U. S. Government Irons, J. v., 1952. Rodent Plague in the Printing Office, Washington, D. C. Texas South Plains, 1947-49. Public Tipton, V. J., 1950. New distributional records Health Monograph, Part II (6): 41-54. for Utah Siphonaptera. The Great Basin Mohr, C. O., 1948. Domestic rats, fleas and Naturalist 10 (1-4): 62-65. native rodents in relation to plague investi- United States Pubhc Health Reports 51 (30): gations in Utah. Communicahle Disease and 65 (39). Center Bulletin, Atlanta, Georgia. (Mime- Wayson, N. E., 1947. Plague—Field surveys ographed) in western United States during ten years Prince, F. M., 1943. Species of fleas on rats (1936-1945). Public Health Reports 62 collected in states west of the 102nd Me- (22): 780-791. ridian and their relation to the dissemi- Wheeler, C. M. and Douglas, J. R., 1941. Trans- nation of plague. Public Health Reports mission studies of sylvatic plague. Pro- 58 (18): 700-708. ceedings Society of Experimental Biology

, 1947. Plague. The survival of the infec- and Medicine 47: 65-66. tion in fleas in hibernating ground squir- Zetek, James, 1917. The ecology of bubonic rels. PubHc Health Reports 62 (13): 463- plague. Annals Entomological Society of 467. America 10: 189-206. 38 Brigham Young University Science Bulletin

PART II communication - H. T. Ricketts, M.D., Chi- cago." ROCKY MOUNTAIN SPOTTED FEVER Since the time of the first investigations VECTOR INVESTIGATIONS and initial discoveries, this disease and its very closely related types (of which there are seve- INTRODUCTION ral) have become somewhat cosmopolitan in their significance. From the very beginning of the occupation It is known that several species of ticks are of the Rocky Mountain region by white man, identified as either capable or potential vectors there have been records of his being affected of Rocky Mountain spotted fever. In the west- by tick-borne diseases. Utah has long con- ern United States in general and Utah in tributed far too many records showing incidence

particular, Dermacentor andersoni Stiles is the of Rocky Mountain spotted fever. Not very much, however, has been known, concerning principal vector transmitting the disease to man. the kinds of vectors involved, their geographical From an historical point of view the disease or seasonal distribution, as well as host re- at fii'st supposed to have been confined to was lationships for the State of Utah. These, how- the Rocky Mountain area and especially so for ever, have been the primary objectives involved the Bitterroot Valley of Montana. At the pres- in the tick vector surveys carried out by the ent time, however, the disease has been found writer and his associates and which comprise the main body of this part of the report. widely distributed throughout the United States Probably the first reference to the disease and parts of Canada. It became recognized as "spotted fever" in Utah is that by Stiles (1905). a medically important disease as early as 1873 On page 28 of his report, the statement reads in Montana, although not a great deal was as follows: knqwn about it at the time. According to Fricks "Sweet (1896) states that the disease does (1915) the United States Public Health Service not to his knowledge occur in Utah, but began investigating the disease in 1902 when J. Smith (1905) reports a possible case." O. Cobb was ordered to Bitterroot Valley, Mon- On page 116 of this report by Stiles is the tana to instigate studies on the disease The fol- account mentioned by Smith in the quote lowing year, 1903, J. F. Anderson was appoint- above. The title of Smith's report which was ed; in 1904 C. W. Stiles took over, followed by included in the paper by Stiles is shown below: Francis, King, McClintric and Rucker, et al. "As possible case of "Spotted Fever" in From a report by Robinson (1908), Wood of Utah by R. J. Smith, M.D. (Personal letter, the U. S. Army submitted to the Surgeon-Gen- dated May 22, 1904, to Dr. Thomas D. eral, descriptions of the disease from eight Tuttle, secretary, Montana State Board of Idaho physicians, and he was the first to refer Health)." to it as "spotted fever." The physicians are It is important to mention that the patient listed as Bowers, Collister, Dubois, Fairchild, to which Dr. Smith made reference in his let- Figgins, Springer, Sweet, and Zipf. ter was, "A patient, female, age 24, was visiting In August, 1906, Dr. Howard T. Ricketts in Idaho, where within 2 miles of the place she published his preliminary results demonstrat- was visiting there were 2 cases of 'spotted fever,' ing the relationship between the disease and the ". . . . Even though this was a case of spotted andersoni. His carefully vector Dermacentor fever occurring in Utah, it is not positive that done, yet simple experiments stand out as one the disease was picked up witliin the confines of the major achievements in the study of tick- of the state. borne diseases. He had reported earlier that Robinson' (1908) refers to the disease with - same year (July 7 Journal of American Medi- respect to its occurrence in Utah as follows: cal Association, Vol. 47, No. 1, pp. 33-36) his "Geographical Distribution. —The disease studies on the disease, as a result of his in- has been reported from Montana, Idaho, vestigations by means of animal inoculations. Wyoming, Nevada, Oregon, Washington, It is of interest to note in his title for the earlier Utah, and Colorado. I am informed by paper the reference to "tick transmission," al- Noyes of American Fork of three cases though he had not completed his investigations occurring in Cedar Valley, Utah. One to that end. The title was: "The Study of 1 This excerpt is from an article which was the prize essay identi- 'Rocky Mountain spotted fever' (Tick Fever?) fied as the Francis W. Shain Prize, Jefferson Medical College, 1908 The essay was made a part of the "Medical Record," a by means of animal inoculations. A preliminary weekly Journal of Medicine and Surgery in New York. Biological Series Vol. 1, No. 1, March, 1955 39

patient was a sheepherder and resided at Also of historical interest is a news refer- Fairfield, while the other two, a farmer and ence supplied by Jellison and Kohls in corres- his daughter, lived at Cedarfort. Wherritt pondence with me on May 12, 1954: had several cases at Heber City (Utah). Copied from Oregon City, Ore., Enterprise Laymen tell me of having contacted June 20, 1941 "Mountain fever" while hauling wood from a district designated as "Tickville," "BRIGHAM YOUNG'S ILLNESS which is about fifteen miles north of the DIAGNOSED AFTER 94 YEARS villages Fairfield and Cedarfort. From the abundance of ticks in this locality the dist- SALT LAKE CITY—Ninety-four years after rict gets its name." he came down with the illness, physicians finally have diagnosed the mysterious The Rocky Mountain Laboratory at Hamil- fever that afflicted Brigham Young at the ton, Montana, has been the main scientific arrival of the Mormon pioneers in the Salt agency which has checked "spotted fever" in- Lake Valley in 1847. cidence as well as vector distribution since Dr. William M. McKay, acting Utah studies were first initiated. The records for health commissioner, disclosed that inten- Utah have been made available for this report sive research and much careful examina- through the courtesy of the personnel of the tion of the daily journals kept by some of Rocky Mountain Laboratory, especially Dr. Young's companions indicated the Mor- William L. Jellison and Mr. Glen M. Kohls mon leader suffered from Rocky Mountain (Tables 1, 2, 3, and 4). In Table 1 note that spotted fever. under the county coliunn there is listed, "un- The disease was unknown at that time, known," date "1849." Below is a copy of a and it was only Young's strong constitution letter which, with special reference to date, that enabled him to survive the ailment. offers some explanation. Dr. McKay believes."

"DISTRICT DIRECTOR In the Kansas State Board of Health Bul- U. S. PUBLIC HEALTH SERVICE letin No. 6, page 103, Rucker (1912) has the following to say with regard to Rocky Mountain District No. 8 spotted fever: 617 Colorado Bldg. "Two types of Rocky Mountain spotted Denver, Colorado fever are known—the mild, which occurs in Utah, Wyoming, Idaho, Nevada, eastern Sept. 27, 1941 California, Oregon, and Washington, and Dr. R. R. Parker the severe form which is found in Mon- Rocky Mountain Laboratory tana." Hamilton, Montana Fricks (1915) reported in the Public Dear Doctor Parker: Health Reports: I recall that are interested in reports you "The State Health Officer of Utah re- of Rocky Mountain spotted fever of an early ports that it is impossible to furnish any historical date. accurate data concerning the prevalence of Perhaps you already know about this, but Rocky Mountain spotted fever in Utah, but in Salt Lake City recently I was shown a regis- that several deaths were attributed to this ter of deaths kept by the Mormon Church near- cause during 1914 and there is reason to ly a hundred years ago. In the year 1849 there believe that the disease occurs in Box Elder are several deaths reported from "mountain County." fever," at least three on one page of the register. "Rocky Mountain spotted fever certain- It is an interesting record, and if you have ly occurs in Utah, but to what extent is not not seen it, it is worth a glance some time. It known and will not be until the disease is is kept at Salt Lake City Health Department, made reportable." Bureau of vital Statistics. I am sure that Doc- One of the first references to vectors of the tor Thomas J. Howells, the Health Commission- disease in Utah is that of Banks (1908), where- er, will be glad to show it to you. in he refers to D. venustus Banks (now con- Respectfully, sidered as a s)Tionym for D. andersoni). He L. B. Byington, Surgeon lists this species from Bridger Basin, Utah. As In Temporary Charge, Dist. No. 8." closely as can be discovered from the records, 40 Brigham Young University Science Bulletin

County 1918 1919 1920 1921 1923

1(1)

1 1 1

3 3

2(1)

1 Biological Series Vol. 1, No. 1, March, 1955 41

County 1924 1925 1926 1927 1928 1929 1930 1931 1932 Beaver

Box Elder 1 1

Cache 2 1 Carbon Daggett

Davis 1

Duchesne 1 3 3(1) Emery

Juab 1 2 3(1) Kane

Millard 1 Morgan

Piute 1 Rich 2

Salt Lake 3 1 San Juan Sanpete

Sevier Summit Tooele Uintah Utah Wasatch Washington Wayne 2

Weber 1

Unknown 10(3) 6(1) 4(1) 8

State Total 10(3) 6(1) 4(1) 8 10 15 8(2) 7(1)20(4)

Table 2. Rocky Mountain spotted fever cases in Utah from 1924 to 1932. (iFg- ures in parentheses indicate fatal cases). ^2 Brigham Young University Science Bulletin

County 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 Beaver Biological Series Vol. 1, No. 1, March, 1955 43

County 44 Brigham Young University Science Bulletin

his geographic location for the collection was in Cooley (1938 and 1946), Cooley and Kohls the northwestern comer of Daggett County, or (1944) and Jellison (1945) published several in the south-central portion of Rich County in comprehensive articles on ticks, in which the Utah. Rocky Mountain spotted fever tick vectors in Bishopp (1911) listed twelve localities for Utah and other states are listed. Bishopp and the Rocky Mountain wood tick in Utah. His Trembly (1945) listed distributional records for accompanying map, however, shows a distri- Utah, from the Bureau of Entomology. Ed- butional pattern for the tick indicating that he munds (1951) has published the only principal must have confused or included the common list to date which is restricted to ticks in Utah. rabbit tick D. parumapertus Neumann with Coffey (1953) has recently made some prelimi- D. andersoni. nary studies on distribution, seasonal occurrence, and host relationships of D. parum- Robinson (1908 loc. cit. p. 916) cited Noyes apertus, D. andersoni, as well as other impli- of American Fork as giving information con- cated vectors of Rocky Mountain spotted fever cerning three cases of Rocky Mountain spotted in Utah. He has also been an associate colla- fever in persons living at Fairfield and Cedar borator on some phases of this project and some Fort. These towns are only a few miles west of his observations are included in this report. of the writer's home at Provo, Utah County, Part of his studies, however, have been pub- Utah. The towns of Cedar Fort (spelled "Ce- lished (1954) and will be referred to according- darfort" by Robinson) and Fairfield are about ly. There are several other reports which have five miles apart. They lie at an elevation of had reference to Utah ticks. They will, how- about 4,800 to 5,000 feet above sea level. To the ever, be cited at the appropriate place in the west are the foothills of the Oquirrh Mountains, main body of the report. rising to an elevation of 10,403 feet at nearby Lewiston Peak. It will be recalled that Wher- Etiological aspects of the disease: ritt as reported by Robinson (1908), laymen told him of contacting mountain fever in a Rocky Mountain spotted fever is caused district known as "Tickville" about 15 miles by Rickettsia rickettsi (Wolbach), (Also listed north of 'Fairfield' and 'Cedarfort' and that this in the literature under the synonym Dermacen- place was named "Tickville" owing to the num- troxenus rickettsi. It is one of the rickettsial ber of ticks found there. To one acquainted organisms of which there are several species. with the topography of Utah, a point fifteen It would be well to mention here that there are miles north of Cedar Fort would be located in several kinds of rickettsial organisms, tick trans- a mountainous area and at elevations where mitted, which are immunologically identical D. andersoni has been commonly foimd. As (or very closely so) to Rocky Mountain spotted recently as April 17,1 954, the writer had first- fever but are located at widely separated places hand reports and received collections in un- on the earth. Nevertheless, the organism in the usual abundance of D. andersoni from moun- western United States, including Utah, is the tain areas west, north and south of Cedar Fort. one listed above and is considered to be endemic These reports and collections came from ele- to the western states. Its pathological effect is vations of 5,500 to 7,000 feet above sea level. mainly directed to the endothelial lining of the blood vessels. The rickettsia are intracellular A survey was conducted on May 29, 1954, as well as intranuclear in their invasion, and at the head of Barlow Canyon in the Boulter produce an exanthematic condition in the en- Mountain area of central Utah. The general dothelia of blood vessels. location for this survey is about eight miles Case fatality varies with different localities, north of Eureka in Juab County and about 20 being characteristically high in the Bitterroot miles south and slightly west of Cedar Fort in Valley of Montana. Generally speaking, the the Cedar Valley area. At elevations ranging case fatality rate has been figured from 4% to from 6,100 feet to 6,900 feet ticks were found 90%, depending on the geographic locality in sufficient numbers to be listed as common. where the disease was contracted. At the uppermost elevation surveyed (7,000 feet above sea level), a place named, "Hot Stuff DISTRIBUTION OF THE DISEASE Mine," the ticks were most abundant. They AND CASE FATALITY were taken by flagging grass and brush situations. The ticks seemed to be more densely In the United States: distributed along stock trails and in the open Rocky Mountain spotted fever has been re- grass locations. ported from every State of the Union. The in- Biological Series Vol. 1, No. 1, March, 1955 45

cidence, however, is higher in the western part the more northern states such as Montana of the United States. Hampton and Eubank and Idaho (Cooley, 1932). One might (1938) over a five year period of observation logically assume that the October and No- (from 1933-37) reported 2,190 cases in the vember cases are probably from hunters U. S.; 1,435 or 65.5% occurred in the Mountain and others whose occupation takes them and Pacific States and 601 or 27.1% occurred into the mountain areas at these times. It in the South Atlantic States. With respect to is generally thought that the tick, D. ander- virulence there is parallel comparison. Topping soni, becomes active early in the spring at (1941) reported the case fatality as being low elevations, but that its seasonal appear- 28.1% in the Western States and 18.4% for the ance is progressively later at higher eleva- Eastern States. In the west it seems to have tions." its most virulent type located in the Bitterroot "An analysis of the case fatality statis- Valley of Montana. tics of spotted fever in Utah, derived from the records supplied by the Utah State In Utah: Health Department, presents some interes- of Through the courtesy Mr. John Wright ting facts. For the nineteen year period, of the Utah State Health Department, statistics 1934 to 1952, the case fatality has averaged on the incidence of the disease in Utah were 17.4%. By breaking the nineteen year available to this survey. made Coffey (1953) period into two periods of six years and one analyzed these statistics and I quote from his of seven years, it was found that the high- report: est fatality mark was during the war years, spotted fever in "Records on Utah are being 27.77% in the period of 1940 to 1945 available at the State Department of as compared with 15.2% in the period Health as far back as 1934. According to 1934 to 1939, and 9.5% in the period 1945 these State health records, spotted fever oc- to 1952." curs in every county in except Piute. Utah For a year-by-year breakdown on inci- (Rocky laboratory Mountain records show dence and fatality records from 1915 to and in- a single non-fatal case for 1930 in Piute cluding 1942, refer to Tables 1, 2, and 3. The See It is least County. Table 2). abund- total number of cases and the case fatality re- ant in the Great Basin and desert areas of ported to the Rocky Moimtain Laboratory from the Colorado Plateau. It is important to re- 1915 to 1942 is shown in Table 4. The average member, however, that cases reported from fatality rate over this period was 12.14% which a county not in all cases have been may is slightly above the post- World War II period contracted there. of the case hist- A study and under the 15.2 percentage from 1934 to tories would no doubt prove valuable as 1939, but markedly under the World War II well as interesting. According to the data percentage of 27.77%. the higher incidence is found in Salt Lake, Utah, Uintah, and Duchesne counties. The HOST RELATIONSHIP AND THE DISEASE former two counties have high population centers in close proximity to foothills and Jellison (1945) has the following to say mountain areas. In the latter two counties regarding the host reservoirs of the disease population centers also border extensive agent: foothills and mountain areas. In addition, "It has long been suspected that Rocky many people enter the brush and forest Mountain spotted fever may have its reser- parts of these counties for reasons of va- voir in some mammal or mammals that cation and recreation." are natural hosts of its tick vectors, i. e., "Rocky Mountain spotted fever in hu- Dermacentor andersoni in the western mans has not been reported until April in United States, Dermacentor variabilis Utah. The disease usually reaches the peak (Say) in the eastern United States, and of its incidence in June, declining there- Amblyomma americanum (L) in some of after, and does not cease in some years un- the South Central and Southeastern states. til the last of November. The earliest case Positive statements regarding such a reser- of spotted fever recorded in Utah is on voir and names of specific animals have

April 1, 1938, and the latest on November been published, but convincing evidence 25 of the same year. The June peak and has not been presented. the autumn cases show a later incidence for In the same paper from which the above Utah than has been reported by others for quotation was taken, Jellison shows the close 46 Brigham Youivtc University Science Bulletin geographical association between Rocky spotted fever has been reported from all Mountain spotted fever and the distribution of states except Maine, Vermont, Connecti- Nuttall's Cottontail in the western United cut, Rhode Island, and Michigan. In Can- States. Nevertheless, he goes on to say; ada, it is present in the provinces of Rritish "Spotted fever infection has never been Columbia, Alberta, and Saskatchewan. recovered from this host or any other mam- Within this endemic region, four species mal in nature in the highly endemic area of ticks are known to be natural carriers in the western United States." (capable vectors), viz., the Rocky Moun- Philip and Hughes (1953) in a report to tain wood tick, Dermacentor andersoni; the the International Congress of Microbiology re- American dog tick, Dermacentor variabilis; port as follows: the lone-star tick, Amblyomma ameri- "The so-called rabbit dermacentor, D. canum; and the rabbit tick, Haemaphysalis parumapertus, is a frequent parasite on leporis-palustris (Parker, 1938; Philip, 19- rabbits and hares in the southwestern 42). D. andersoni is the well-known vector United States, particularly on the black- in the Rocky Mountain region and adjacent tailed jack "rabbit" (hare) in the arid and area. D. variabilis is the vector in the subarid areas. The distributional records Great Plains region and eastward to the of this hare and tick show a remarkable Atlantic seacoast. It is also found in Cali- coincidence." fornia and occasionally in Oregon; it occurs "During population studies of these in the southern provinces of Canada from hosts, opportunity has been afforded to re- Saskatchewan eastward, and it is found in cord for the first time, natural infection in Mexico. A. americanum, the most recent these ticks with three agents of human addition to the list of proved carriers (Par- disease: namely, Bacterium tularense of ker, Kohls, and Steinhaus 1943), occurs tularemia, a Rocky Mountain spotted fever- in the southcentral and southeastern states, like Rickettsia, and the virus of Colorado and as far south as Panama. Reports of its tick fever. The strains of the first were occurrence in South America have not been virulent for laboratory rabbits, and for verified. H. leporis-palustris occurs hares imported from Kansas. The strains throughout the United States, southward of Rickettsia were less virulent for guinea into South America, and northward into pigs than a laboratory passage strain of R. Canada and Alaska." rickettsi of origin human and showed cer- "In the category of potential carriers tain immunological differences." (vectors) in the United States are 5 species "D. parumapertus, however, has been which are efficient experimental vectors, be shown to as capable of experimental any one or more of which may be function- transmission of virulent spotted fever ing as natural vectors at the present time. strains as D. andersoni, the vec- customary These are the Cayenne tick, Amblyomma tor to in man the Rocky Mountain area." cajennense; the Pacific Coast tick, Der- "Even though D. parumapertus feeds al- macentor occidentalis; the rabbit derma- most exclusively in most areas of its range centor, D. parumapertus^ the brown dog rabbits hares, on and the above information tick, Rhipicephalus sanguineus, and Orni- is suggestive that this species of tick can thodoros parkeri. All of these are known act in natural maintenance of the above to attack man, the last three only rarely. indirectly in infection of in agents and man It seems apparent that R. sanguineus bites appropriate localities." man more frequently in other parts of the the studies date, it only From made to can world than in this country. It is not known be concluded on circumstantial evidence that whether this represents an actual differ- there hosts for the are many natural reservoir ence in host selection or is merely indica- disease organism. tive of a greater opportunity for biting provided by a closer association of man with VECTOR AND DISEASE RELATIONSHIP tick-infested animals, especially the dog." IN NORTH AMERICA Ricketts (1907) according to Cooley (19- Kohls (1946) reporting at a symposium on ric- 32) accidentally demonstrated experimentally kettsial diseases of man, has the following to that Dermacentor alhipictus could be a vector say regarding the vectors of the disease: of Rocky Mountain spotted fever. Philip and "In the United States, Rocky Mountain Kohls (1951) reported a spotted fever case as Biological Series Vol. 1, No. 1, March, 1955 47 probably due to D. albipictus Packard. The list Laboratory in Hamilton, Montana. However, of vectors in the U. S., therefore, includes a most of the data derived have been from results total of ten species, five genera and two families. of studies made under natural conditions as well The vector itself is apparently not affected as under controlled laboratory conditions at that by the rickettsia. A tick when once infected, geographic area. Kohls (1937) describes in however, remains so permanently and can also some detail tick rearing methods for D. ander- transmit the disease organism from generation soni. No complete life history study has been to generation congenitally, (transovarialj. made of D. andersoni or any other species of When the human host becomes inoculated by tick under Utah conditions. Some very ele- an infected tick, a distinct malaise sets in. The mentary observations have been made in our degree of pathogenicity is predetermined in studies, however, which, it is felt, should be part by the virulence of the strain of rickettsia reported upon. Before referring to these obser- injected, coupled with the inlierent resistance vations, a few general statements would be in man may present to the disease. order regarding the life history of the Rocky Mountain wood tick, D. andersoni.

VECTOR AND DISEASE RELATIONSHIP Generally speaking, the life history stages IN UTAH of D. andersoni are as follows: The adult engorged female lays several thousand eggs fol- As far as is known, D. andersoni is the only lowing her emergence from hibernation in early tick in Utah which transmits the disease from spring of March and April. The feinale dies up- man to man or from natural reservoir host to on completion of egg laying. The eggs hatch man. Haemaphysalis leporis-palustris (Pack- as larvae which possess six legs. They attach ard), the rabbit tick, is fairly widespread themselves to the smaller rodents if the latter throughout Utah (Fig. 9). It is considered as are present in the vicinity (Fig. 5 and Table 6). the most prominent capable vector of the di- After foiu- to seven days' engorgement on the sease among rabbits and thus perpetuates the host, the larvae drop off and undergo a molt, disease reservoir in nature (?). emerging as nymphs in late The common rabbit dermacentor, Der- summer. The nymphs then usually hibernate over the winter macentor parumapertus, is widely distributed in that stage. The following spring, the nymphs in the Great Basin portion of Utah (Fig. 8). emerge from hibernation, attach themselves to From experimental evidence, it is considered as a large, warm-blooded animal, engorge them- a potential vector. It is perhaps the tick most selves, drop from the host, molt again, emerge commonly met with at lower elevations in the as adults and start the cycle over again. These southern part of Utah as well as the western adults are the ones which become active the fol- half of the State. Rhipicephalus sanguineus lowing spring. minimum of two year's time (Latreille) the brown dog tick, has been re- A is required ported from Utah only twice (Edmunds 1951). to complete the cycle, and three hosts are involved. Davis (1943) by experimental testing showed Ornithodoros parkeri Cooley to be a "potential" Coffey (1953) in making some studies on vector of Rocky Mountain spotted fever. Col- seasonal variations with respect to populations lections as reported in the literature and from of D. andersoni and D. parumapertus at widely our surveys show scattered distribution for this separated locations in the northern part of the species in Utah. Great Basin area in Utah, has the following to Generally speaking, the adult tick of D. say: andersoni and D. parumapertus. live on mam- "D. andersoni first becomes active in the mals the size of the jack rabbit, and larger when spring of the year at lower elevations, re- feeding. D. parumapertus as adults are some- maining in hibeiTiation at the higher ele- what restricted to L. californicus as the princi- vations until later in the season." pal host. The immature stages of both D. ander- Coffey's observations, as well as those by soni and D. parumapertus, however, are con- the writer, indicate that the appearance of the sortes of smaller animals (Figs. 2 and 5). adults in the springtime is in part regulated by the current climatic conditions and altitude. LIFE HISTORY NOTES AND The earliest record of an adult D. andersoni tick ON SEASONAL VARIATION being taken in Utah is one collected by the D. andersoni author on March 2, 1954. This tick was re- The life history of this species of tick has moved from a young boy who had been hiking been carefully studied at the Rocky Mountain in the foothills near Provo, Utah. The weather 48 Brigham Young University Science Bulletin Biological Series Vol. 1, No. 1, March, 1955 49 50 Brigiiam Young University Science Bulletin had been extremely balmy for a few days. This a close correlation in activity but a wide vari- was followed by a snow storm and a very cool ation in total numbers of specimens collected. period for several weeks, in which no ticks Immature stages are in evidence from May were found. Following the cold spell, another until September (Fig. 4). occurred and the ticks were very warm period D. PARUMAPERTUS^ active again. On April 10, eighty- three ticks With respect to life history notes and were taken from a student engaged in geological seasonal variations for this species, I will quote survey work at the south end of Cedar Valley from Coffey's (1953, op. cit., 61) records on near Eureka, Juab County, Utah. On the 17th p. Dermacentor sp. He established two stations in of April, 1954, three other student geologists the Great Basin area of Utah. One station was from the Brigham Young University removed at a broad, low-lying desert valley between two 40, 23, and 12 ticks, respectively, from their mountain ranges known as Cedar Valley in bodies following the day's work in the same Utah County. The other was at Lucin in Box area, and all ticks were adults of D. anderscni. Elder County at the western edge of the Great From collection records and reports from Salt Lake Desert in northwestern Utah: literature, it appears that the peak activity of "In view of the fact that adults of D. adult populations for most of the range of D. andersoni have not been taken in the Lucin andersoni in Utah is later than that determined study and that all of the rearing yielded for Idaho and Montana. It is reached about the only one specimen of D. andersoni, it seems last week in April and the first week in May, probable to conclude that the immature depending on weather conditions and elevation Dermacentor sp. in these studies (Lucin (Fig. 1). During the late spring, summer and and Cedar Valley) are in the majority D. fall D. andersoni begin to taper off in numbers parumapertus. In the early spring larvae at the lower elevations but still can be found at and nymphs are abundant." higher elevations. The most consistent host on "If these ticks are parumapertus which this species of tick can be expected to be D. an is presented, found in the late months of the year. (August, interesting problem namely, engorged females of D. parumapertus September, and October) is the Porcupine Eret- no hizon dorsatum. were found during the winter months A few rearing experiments were carried which would be necessary unless the larvae hibernate over winter. interesting out with nymphal stages of Dermacentor sp. An in its right be the rear- They were allowed to engorge themselves on problem own would all stages of Der- guinea pigs until they were ready to molt. In ing of the immature macentor collected in area such as Cedar all cases except one the nymphs emerged as an Valley." adult D. parumapertus . The exception was a D. andersoni. It was one of two nymphs taken "Another intriguing problem regarding from a jack rabbit, L. californicus, in Cedar Val- these ticks is brought to one's attention by a ley, Utah County, Utah, in July. statement in the literature. Bishopp and Trembley (1945) say that the immature From data at hand it seems safe to say that forms of D. parumapertus are usually the majority of Dermacentor in all stages of de- in the cooler of the year, velopment found at the lower elevations in the found months from September to data Great Basin region (desert valley and basins) May. The in Utah, would be D. parumapertus. gathered in this study does not show this seasonal pattern. Bather, it is nearly the Very few immature ticks of D. andersoni opposite. Of course, as previously point- have been collected at the lower foothill ele- ed out, one cannot be certain that these im- vations or mountainous areas diu-ing the peroid mature forms are all D. parumapertus. of this survey. This is the level where it might Begardless of this, the fact remains that no be expected that D. andersoni would be located. immature forms of Dermacentor were There are records from our survey which, found in this study in the winter months." though isolated, do give definite evidence that In direct contrast wdth the absence of col- both species (D. andersoni and D. parumaper- lections for adult D. andersoni during the win- tusq overlap in their distribution (Table 5). ter months in Utah, D. parumapertus adults The Dermacentor ticks immature found at have been collected every month of the year high altitudes would most likely be D. ander- The immature stages of D. andersoni and D. parumapertus are ex- soni. An examination of these collections of im- tremely difficult to separate taxonomically. Tfie only reliable mature ticks obtained metfiod of determination is to rear tliem through to adulthood and by our survey indicates then classification can be done more accurately. 51 Biological Series Vol. 1, No. 1, March, 1955

Citellus armatus

Citellus lateralis ssp.

Citellus richardsoni

Citellus leucurus ssp.

Citellus townscndii ssp.

Citellus variegatus ssp.

Citellus beldingi

Cynomys leucurus

Dipodomys microps

Dipodomys merriami ssp,

Dipodomys ordii ssp.

Eutamias minimus ssp

Eutamias quadrivittatus ssp.

Eutamias dorsalis

Lepus californieus ssp

Lepus townsendii ssp.

Marmota flaviventer ssp. Micropipodops megacephalus ssp. Microtus montanus ssp.

Microtus longicaudus morda.x

Mustela erminea ssp.

Neotoma lepida ssp.

Neotoma albigula ssp.

Neotoma cinerea ssp.

Ociiotona princeps ssp.

Onyehomys leucogaster ssp

Perognathus parvus ssp

Perognatlius longimembris ssp.

Perorayscus maniculatus ssp

Peromyscus crinitus ssp.

Peromyscus truei

Peromyscus eremicus

Rattus rattus rattus

Reithrodontomys megalotis

Sylvilagus auduboni ssp.

Sylvilagus nuttallii ssp.

Sylvilagus sp.

Sciurus aberti ssp.

Tamiasciurus hudsonicus ssp,

Zapus princeps 130 140 150 160 170 180 10 20 30 40 bO 60 70 80 90 100 110 120

of Dermacentor sp., removed Fig 5 Comparative numbers of larval and nymphal tick collections number represents in each from various species of hosts over a five year period in Utah. The total of ticks collected. case the collections made in the five year period and not the total number 52 Brigham Young University Science Bulletin

(Fig. 1). The predominant months of activity than D. andersoni. Data gathered on this sur- as adults, however, are from March through vey agree closely with reference on life history September from collection records made by this habits as reported in the literature (Fig. 3). As survey. Immature stages have been observed the distributional range is extended southward, as having peak activity from March through the various stages in the life history of this wide- June. This has been found to be the case for ly spread tick becomes modified. For example, nymphs and larvae collected from hosts in geo- there are both nymphal and adult populations graphic areas mentioned above where it can be in evidence during winter in the southwestern assumed that the ticks are D. parumapertus corner of Utah, which is in the southern desert (Fig. 2). Figure 6 shows this seasonal variation shrub commimity and possesses a mild winter in the activity of larvae and nymphs as found climate. On December 21, 1950, sixty nymphs at the two widely separated geographical lo- and 121 adults were removed from the cotton- cations of Lucin and Chimney Rock Pass—Ce- tail, Sylvilagus auduboni, at Beaver Dam Wash, dar Valley areas in the Great Basin region. Washington County, Utah. The latest date for The collections at Lucin were made in a nympal collection in the northern (northern February, May, June and October. At the Ce- desert shrub community) part of the State has dar Valley-Chimney Rock Pass station col- been September 30, 1949. One nymph was re- lections were made on a monthly basis. An moved from a Lepus californicus and one from analysis of data from the Chimney Rock Pass- Sylvilagus nutallii at Heber, Wasatch County, Cedar Valley collections reveals a great abund- on that date. It is interesting to note that our ance of larvae as compared to nymphs for survey records for the months of January and March and April. There were 811 larvae and February show no reference to specimens of

103 nymphs removed from 38 hosts during H . leporis-palustris of any age having been col- March. In April there were 915 larvae and 59 lected. Edmunds' (1951), op. cit., p. 25-26) nymphs removed from 30 hosts. In May the references to collection dates all show summer ratio begins to reverse itself for both the Lucin collections. Apparently, this tick does not have and the Cedar Valley-Chimney Rock Pass col- a very extensive winter activity in the northern lections. In May at Lucin there were 496 lar- or colder parts of Utah. vae and 674 nymphs removed from 54 hosts. Ornithodoros parkeri and Dermacentor At Chimney Rock Pass-Cedar Valley 29 larvae ALBIPICTUS and 436 nymphs were collected from 15 hosts. collection records for these species For the month of June at Lucin, 61 nymphs and The sufficiently numerous to give the complete absence of larvae were noted on have not been life history data. 23 hosts while at Chimney Rock Pass-Cedar significant Valley 44 nymphs and only 6 larvae were found on 10 hosts for the same month. An unex- VECTOR HOST ASSOCIATION plained increase in larvae over nymphs for AND DISTRIBUTION August through October was found in the Cedar D. ANDERSONI: Valley-Chimney Rock Pass collections. This Information obtained from the literature was likewise the condition however for the Lu- and the data resulting from this survey show cin collections. In October there were 67 larvae that this tick does not demonstrate any marked and 49 nymphs taken from 15 hosts, while at host specificity, either as immature or adult or- the Chimney Rock Pass-Cedar Valley area, 50 ganisms. Very few larvae or nymphs of what larvae and the complete absence of nymphs was could be occurately identified as this species are found to be the result of the examination of 4 listed for this survey. It will be recalled that host mammals (Fig. 6). the larvae and nymphs of this species are very careful, complete life history of this A difficult to accurately separate taxonomically species under Utah conditions is needed in order from the rabbit tick (D. parumapertus). With accurately determine population trends to more but one exception, at no time during the period on a seasonal basis. of this survey was an adult tick removed from a host smaller than the Snow Shoe rabbit Lepus HaEMAPHYSALIS LEPORIS-PALUSTRIS americanus. The one exception was the collec- The egg-laying activity of this species over tion of an adult male on a Peromyscus manicu- most of the State of Utah follows somewhat the latus at Aspen Grove, Mt. Timpanogos, Utah same pattern as D. andersoni. However, the County, Utah. Most of our adult tick collection immature stages are in evidence much longer records are from man. The next most common Biological Series Vol. 1, No. 1, March, 1955 53

1^-»

> o

(B T3 ttf E ^° °a; > o

nj tl 111

s-^ -

§ §

o ^

.^ E o O (D

c r E O 3 6 ^ a, ao c c o O 3

CO M J w0) £ o w

)" 3

C5 54 Brigiiam Young University Science Bulletin vector-host was the porcupine E. dorsatum. This vilagus nuttallii, Peromyscus maniculatus and was followed by the jack rabbit, (L. californi- Lepus tow?iscndii. cus), mule deer (Odocoilus hemioniis) and the The only reliable system for species identi- domestic sheep. Other collections are from the fiction of immature stages v^here D. parum- bob cat skunk. and apertus and D. andersoni are concerned is to Many specimens of nymphal and larval rear these stages on through to adulthood. From stages of Dermacentor have been collected (Fig. the few rearing experiments conducted in this 5). For reasons mentioned previously, these project there is sufficient evidence to support specimens "specific" were not given status and the theory that D. parumapertus is predomi- have been here listed as Dermacentor sp. nantly a desert inhabiting fonn. Nevertheless, there are sufficient data at hand If such is the case, and it seems to be ap- to indicate that larvae and nymphs of the genus parent, then the immature ticks of D. parum- Dermacentor collected at higher altitude lo- apertus are found on a variety of hosts (Table cations (montane) would most likely be D. 5). Table 6 shows the distribution by county andersoni. Those immature stages at lower ele- for the adult forms of this species. Figure 8 vations (desert) would probably be D. parum- shows the distributional pattern for adults with- apertus (Table 5 and Fig 6). in the State. This figure includes data from Those specimens collected at the foothill both the records in literature as well as from areas (the ecotonal situation between the mon- collections made by this survey. tane and valley or desert shrub communities) Haemaphysalis leporis-palustris could be either one of the two species. In tliis study a single male adult D. parumapertus was This species of tick in Utah has been collec- collected at Aspen Grove, on Mt. Timpanogos ted most often on the various species of the in Utah County, May 23, 1951: host, Peromys- family Leporidae (rabbits). The species of rab- cus maniculatus. The appro.ximate elevation bits are as follows: Sylvilagus auduboni, Sylvi- at the place of collection was 7,000 feet. Like- lagus nuttallii, Sylvilagus idahoensis, Lepus wise, in July, 1952, one of two nymphs collected calljamicus, Lepus toivnsendii. Other hosts with from Lepus californicus in Cedar Valley, Utah which the tick was less commonly associated County, Utah, was reared through to adulthood are the pack rat {Neotoma cinerea), the ground and proved to be D. andersoni. The elevation squirrel (Citcllus variegatus), and the green in the valley where the collection was made is tailed towhee {Oberholseria chlorura). about 4,800 feet. It is interesting to note that Green, Evans The most specific host-vector association and Larson (1943) found that snowshoe hares with regard to nymphal and larval collections were the preferred hosts in Minnesota and even of this survey for Dermacentor sp. is shown in ruffed grouse were more important hosts than Table 5. cottontails. In our surveys no ticks of this spe- Space does not permit an extended listing cies have been taken from the aspen or coni- for each collection record made throughout the ferious belts where the rabbits Lepus ameri- State during this survey. Distribution by coun- canus and Lepus townsendii have been collect- ty, however, has been prepared in table form ed. Generally speaking it may be concluded for D. andersoni and other ticks implicated with from our surveys that this species of tick is oRcky Mountain spotted fever (Table 6). found commonly in desert situations or under Figures 7 illustrates the distributional pat- desert-like conditions at higher elevations where is sage, tern in the state for the adult of this species. the predominant plant growth grease-

rabbit brush (Fig. . This distributional pattern is derived from both wood and 9) published records and collection records ob- Dermacentor albipictus tained by this survey. This tick has been reported from the deer Dermacentor parumapertus (Odocoileus hemionus Rafinesque), the antelope {Antilocapra americana Ord), and the horse Whereas D. andersoni adults show a wide (Edmunds loc. cit., p. 25). The only collections range of host selections, D. parumapertus ad- taken by this survey were from elk (Cervus ults are more restricted. Lepus californicus is canadensis Allen) in Cache County. by and large the predominant host animal for adult D. parumapertus. Other hosts on which Ornithodoros parkeri they have been collected during this survey Several sample collections have been taken are Dipodomys ordii, Perognathus parvus, Syl- from burrows of the prairie dog of the genus Biological Series Vol. 1, No. 1, March, 1955 55

MONTANE (high altitudes) ECOTONAL (foothill) DESERT (low altitudes)

Vector: Vector: Vector:

D. andersoni D. andersoni or D. parumapertus

D. parumapertus

Host: Host: Host:

Lepus townsendii Sylvilagus nuttallii Lepus calijornirus

Ochotona princeps Sylvilagus auduboni Sylvilagus auduboni

Peromyscus maniculatus Peromyscus maniculatus Sylvilagus nuttallii

Zapus princeps Peromyscus truei Peromyscus maniculatus

Citellus lateralis Peromyscus crinitus Peromyscus eremicus

Citellus armatus Rattus norvegicus Reithrodontomys megalotis

Sciurus aberti Neotoma cinerea Rattus norvegicus

Neotoma cinerea Eutamias minimus Peromyscus crinitus

Marmota flaviventer Eutamias dorsalis Perognathus parvus

Mustela erminea Eutamias quadrivittatus Perognathus longimembris

Erethizon dorsatum Citellus variegatus Perognathus formosus

Microtus longicaudus Thomomys bottae Dipodomys microps

Oberholseria chlorura Dipodomys ordii

(Bird host) Dipodomys deserti Dipodomys merriami

Onychomys leucogaste^

Microdipodops sp.

Citellus variegatus

Citellus leucurus

Cynomys leucurus Eutamias minimus

Eutamias dorsalis

Neotoma lepida

Thomomys bottae

Table 5. Vector-host relationships for D. andersoni and D. parumapertus with reference to col lections made at low and high altitudes. 56 Brigiiam Young University Science Bulletin Biological Series Vol. 1, No. 1, March, 1955 57

IDAHO

114 42 UTAH

BOX ELDER 41 41

TOOELE 40- 40 o 2 JUAB o 5 z

39 39

MILLARD GRAND

S8 38

WASHINGTON

SAN JUAN 37 . 57

114 113 lie III 110 ARIZONA

Fig. 7. Distributional pattern for collections of Dermacentor andersoni in Utah. Each dot on the map represents a single collection and does not indicate the numbers of specimens taken in each collection. 58 Brigham Young University Science Bulletin

DAHO

ARIZONA

Fig. 8. Distributional pattern for collections of Dermacentor parumapertus in Utah. Each dot represents a collection record and does not indicate the numbers of specimens taken in a single collection. Biological Series Vol. 1, No. 1, March, 1955 59

IDAHO

42 UTAH

BOX ELDER .41 41

TOOELE 40- 40

< JUA8^ O Q UINTAH O % B UJ >

39 39

MILLARD

BEAVER

38 98

SAN JUAN 37 3T

ARIZONA

Fig. 9. Distributional pattern for collections of Haemaphysalts leporis-palustris In Utcih. Each dot represents a single collection record and does not indicate the number of specimens collected. .

60 Brigham Young University Science Bulletin

Cynomys. Not all colonies (prairie dog towns) Adults of D. parumapertus have been ta- produced these soft-bodied ticks when collec- ken at all seasons of the year in Utah. No en- tions were made. Nevertheless, it is presumed gorged famales, however, have been taken dur- that most of the active "dog" towns will provide ing the winter months. Nevertheless, larvae be- ticks when carefully examined at the appropri- gin to appear in early February. Both larvae ate season. and nymphs are active from February through October with peak activity occurring during SUMMARY AND CONCLUSIONS May and June. Peak activity for adults is during the month of July. Although some data have been gathered Collection in Utah of Dermacentor albipic- in Utah on vectors of Rocky Mountain spotted tus and Ornithodoros parkeri are too scanty to fever, no state-wide surveys have been conduct- be significant, yet our data seem to agree with ed. In the present study special attention has information obtained from other areas. been directed to geographic distribution of both vectors and host, vector-host relationships, and Disease and Disease-Vector Relationship seasonal variation in populations of vectors There are sufficient data to indicate that throughout the State. Some data have been Rocky Mountain spotted fever is indigenous to gathered on the life history of the vectors, and Utah. The disease was first identified as such in a brief discussion of the historical aspect of the 1905 in Utah, and has since that time been disease, its incidence in Utah and elsewhere is found in every country of the State. From also given. 1915-1942 there were recorded 313 cases with Geographic distribution 38 deaths, approximately 12.14% mortality. From data compiled by The Utah State Depart- Of the four capable vectors listed as present ment of Health in 1934-1952, the average num- in the United States, Derniacentor andersoni ber of cases per year was 12.3%. The fatality and Haemaphysalis leporis - palustris are found rate has averaged 17.4%. in Utah. Listed for Utah as potential (experi- With regard to vector transmission D. an- mental) vectors are Dermacentor parumaper- dersoni is the only tick of consequence in Utah tus, Dermacentor albipictus, Rhipicephalis son which bites and can transmit the disease. guineas and Ornithodoros parkeri. Of the po- man An abundance of data indicate that other species tential vectors D. parumapertus is the only spe- of ticks are involved in the transmission of the cies having extensive distribution in Utah. disease among animals and man and thus main- Dermacentor andersoni has a wide geo- tain a disease reservoir in nature. However it graphic distribution but is generally restricted should be emphasized as described by Jellison: in altitude to foothills and mountainous areas. "Positive statements regarding such a reservoir When found on hosts in lowlands and desert and names of specific animals have been pub- areas it is possible that the host migrated from a lished, but convincing evidence has not been higher altitude to a lower level. presented." Haemaphysalis leporis - palustris has a state-wide pattern of distribution. It is more HOST RELATIONSHIP common at lower altitudes in basins, valleys and desert-like conditions whether flatland or can- Dermacentor andersoni adults are mainly yon. This may be due in part to certain pre- found on the larger vertebrate- hosts, indicating ferred hosts, members of the family Leporidae no special host preference. Lepus californicus, being more abundantly distributed at lower the black tailed jack rabbit would represent the elevations. lower limit in the smaller sized vertebrates. The The geographic distribution of Dermacen- immature stages of this tick (larvae and tor parumapertus in Utah is in the main rele- nymphs) likewise show no particular host gated to the Great Basin area. It invades to a prefernce, being found on a variety of small limited extent the southernmost part of the vertebrate mammals, primarily of the order Colorado River drainage basin just north of the Rodentia. Utah-Arizona boundary. The Haemaphysalis leporis - palustris ticks Dermacentor albipictus and Ornithodoros have been collected most often on the various parkeri apparently are localized in distribution. species of the family Leporidae. It has been less Rhipicephalis sanguineus collections seem to in- commonly found on such animals as Neotoma dicate an accidental occurrence of this species in cinerca, Citellus variegafus, and the green tailed Utah. towhee {Oberholseria chlorura) Biological Series Vol. 1, No. 1, March, 1955 61

The adults of the potential vector. Derma- disease. Public Health and Marine Hos- center parumapertus, are somewhat restricted pital Service of the United States Hygienic in host relationships. Lepus calijornicus is the Laboratory Bulletin No. 14. predominant host animal, in fact the distribu- Anigstein, Ludwik, 1944. Recent developments tional pattern for the tick is almost identical in the problem of spotted fever. Texas with that of the rabbit. Other hosts on which State Journal of Medicine 40; 199-202. the adults have been collected are Dipodomys Badger, L. F., 1932. Rocky Mountain spotted ordii, Perognathus parvus, Sylvilagus niittallii, fever (Eastern type). Virus recovered Peromyscus maniculatus, and Lepus townsendii. from the dog tick Dermacentor variabilis, The innnature stages (larvae and njTuphs) of found in nature. Public Health Reports this tick species are found on a wide variety of 47(53): 2365-2369. small mammals, primarily of the order Ro- dentia. Banks, Nathan, 1908. A revision of the Ixo- Dertnacentor albipictus has been collected doidea, or ticks of the LTnited States. U. S. Department of Agriculture, Bureau of from the deer {Odocoileus hemionus) , antelope {Antilocarpa americana), the domestic horse, Entomology, Technical Series No. 15. and the elk, {Cervus canadensis). Beck, D E.; Barnum, A. H. and Moore, L., 1953. Ornithodoros parkeri seems to be associated Arthi'opod consortes in the nests of Neo- with the various species of the genus Cynomys, toma cinerea acraia (Ord) and Neotoma the prairie dogs. However, examination of some lepida lepida Thomas. Proceedings of the "dog towns" failed to reveal specimens of this Utah Academy of Sciences, Arts and Let- vector. ters 30: 43-52. Regarding the unmature specimens of D. Bequaert, Joseph C, 1945. The ticks or Ixo- andersoni and D. parumapertus, it is practically doidea of the northeastern United States impossible to accurately classify them to species. and Eastern Canada. Entomologica Ameri- Their morphology and anatomy are almost cana 25: 73-232. identical. Rearing techniques need to be em- Bishopp, F. C, 1911. The distribution of the ployed to obtain adults from immature stages Rocky Mountain spotted fever ticks. LT. S. in order accurately identify to a vector species.* Department of Agriculture Bureau of Ento- mology Circular No. 136. LIFE HISTORY AND SEASONAL , 1933. Ticks and the role thej^ play in the VARIATIONS IN POPULATIONS transmission of diseases. Smithsonian In- A minimum of two years' time is required stitution Annual Report 289-406. to complete the life cycle of D. andersoni, and , 1936. Rocky Mountain spotted fever ticks. three hosts are involved. The earliest record for Insect Pests Survey Bulletin U. S. Depart- adult emergence in Utah is March 2, 1954, and ment of Agriculture 16 (10): 534. adult specimens have been collected as late as ; Smith, C. N., 1936. American Dog tick October. Emergence of adults, however, occurs {Dermacentor variabilis Say). Insect Pest progressively later as increase in elevation is Survey Bulletin U. S. Department of Agri- encountered. Peak activity is in April and May culture 16 (5): 210. depending on climatic conditions and elevation. and Trembly, Helen L., 1945. Distribu- No adult specimens have been collected from tion and hosts of certain North American November through Febioiary. ticks. Journal of Parasitology 31 (1): 1-54. The egg lying activities of Haemaphysahs tick, leporis - palustris is similar to that of D. ander- Brown, J. H., 1945. The rabbit Haema- soni. This tick seems to be active much longer physalis leporis-palustris Packard, as an seasonally in the warmer parts of the state. No ectoparasite of man. Canadian Entomolo- specimens, however, have been collected in any gist 77: 176. part of the State during the months of January Bun-ows, William, 1949. Jordan-Burrows Text- and February. In midsummer the tick is most book of Bacteriology, 15th Edition. Phila- active in all stages of growth. July is the month delphia: W. B. Saunders Company. of peak activity. Cobb, J. 0., 1902. The so-called spotted fever of the Rocky Mountains, a new disease in LITERATURE CITED the Bitterroot Valley, Montana. Public Health Reports 17(33): 1868-1870. Anderson, J. F., 1903. Spotted fever (Tick fever) of the Rocky Mountains: A new Coffey, Marvin D., 1953. Some preliminary 62 Brigham Young University Science Bulletin

studies of Rocky Mountain spotted fever history of the rabbit tick Haemaphysalis vectors in Utah. Unpublished Masters leporis-palustris, in Oklahoma. Proceed- Thesis, Department of Zoology and Ento- ings Entomological Society, Washington 44 mology, Brigham Young University. (7): 145-149.

Coffey, Marvin D., 1954. A study of some and Joyce, C. R., 1944. The seasonal his- Rocky Mountain spotted fever vectors and tory and hosts of the American dog tick, their hosts in Utah. The Great Basin Dermacentor variabilis in Iowa. Iowa Naturalist 14 (1-2): 31-37. State College Journal of Science 18 (3): 313-324. Cooley, R. A., 1911. Tick control in relation to Rocky Mountain spotted fever. Mon- Edmunds, Lafe R., 1951. A check list of the tana Agricultural Experiment Station Bul- ticks of Utah. Pan-Pacific Entomologist letin 85. 27 (1): 23-26.

, 1932. Rocky Mountain wood tick. Mon- Fricks, L. D., 1915. Rocky Mountain spotted tana Agricultural Experiment Station Bul- fever. A report of its investigation and of letin 268: 1-58. measures undertaken for its eradication

, 1938. The genera Dermacentor and Oto- during 1914. Public Health Reports 30 centor (Ixodidae) in the United States (3): 148-165. with studies in variation. National Insti- Gregson, J. D., 1951. Notes on the spring ac- tutes of Health, Bulletin 171. tivity of the Rocky Mountain wood tick. Cooley, R. A., 1946. The genera Boophilus, Proceedings Entomological Society of Brit- Rhipicephalis and Haemaphysalis (Ixo- ish Columbia 47: 4-7. didae) of the New World. National Insti- Green, R. G.; Evans, C. A., and Larson, C. L., tutes of Health, Bulletin 187. 1943. A ten-year population study of the and Kohls, Glen M., 1944. The genus rabbit tick, Haemaphysalis leporis-palus- Amblyomma (Ixodidae) in the United tris. American Journal of Hygiene 38 (3): States. Journal of Parasitology 30 (2): 260-281. 77-111. Hampton, Brock C. and Eubank, H. G., 1938. and Kohls, Glen M., 1944. The Argasidae Rocky Mountain spotted fever: Geographi- of North America, Central America and cal and seasonal prevalence, case fatality Cuba. American Midland Naturalist, and prevention measures. Public Health Monograph No. 1. Reports 53 (24) : 984-990. and Kohls, Glen M., 1945. The genus Hooker, W. A. and Bishopp, F. C, 1912. The Ixodes in North America. National Insti- life history and bionomics of some North tutes of Health, Bulletin 184. American ticks. U. S. Department of Agri- Davis, Gordon E., 1941. Ornithodoros parkeri culture Bureau of Entomology Bulletin and relapsing fever spirochetes in Utah. (106): 239. Public Health Reports 56 (52): 2464-2468. Hunter, W. D. and Bishopp, F. C, 1911. The

, 1942. The Rocky Moimtain spotted fever Rocky Mountain spotted fever tick. U. S. rickettsia in the tick genus Ornithodoros. Department of Agriculture, Bureau of Proceedings Sixth Pacific Science Congress Entomology Bulletin 105. 5: 577-579. Jellison, Wm. L., 1945. The geographical dis-

, 1943. Experimental transmission of the tribution of Rocky Mountain spotted fever spotted fevers of the United States, Colum- and Nuttall cottontail in the Western bia and Brazil by the Argasid tick Orni- United States. Public Health Reports 60 thodoros parkeri. Public Health Reports (33): 958-861.

58 (32): 1201-1208. , 1934. Rocky Mountain spotted fever. Dyer, R. E., 1935. Rocky Moutain spotted fever. The susceptibility of mice. Public Health American Journal of Nursing 35: 633-640. Reports 49 (II): 363-367. rabbits ; Badger, L. F. and Rumreich, A., 1931. and Parker, R. R., 1945. Rodents, Rocky Mountain spotted fever (Eastern and tularemia in North America: Some type) transmitted by the American dog zoological and epidemiological considera- tick Dermacentor variabilis. Public Health tions. American Journal of Tropical Medi- Reports 46 (24): 1403-1413. cine 25 (4): 349-362. Eddy, Gains W., 1942. Notes on the seasonal Kohls, Glen M., 1937. Tick rearing methods :

Biological Series Vol. 1, No. 1, March, 1955 63

with special reference to the Rocky Moun- Philip, C. B., 1937. Six years intensive obser- tain wood tick, Dermacentor andersoni vation on seasonal prevalence of a tick Stiles. Culture methods for Invertebrate population in Western Montana. Public Animals, Ithaca, New York. Comstock Health Reports 52: 16-22. Publishing Company. , 1939. Ticks as vectors of animal diseases.

, 1946. Vectors of Rickettsial Diseases. Canadian Entomologist 71: 55-65. Rocky Mountain Laboratory Publication , 1942. Rocky Mountain spotted fever: 278 (Mimeographed) known and potential tick vectors in the United States. Proceedings Pacific Sci- , 1947. Vectors of Rickettsial diseases. 6th Annals of Internal Medicine 26 (5): 713- ence Congress 5: 581-584. 719. and Hughes, L. E., 1953. Disease agents and Parker, R. R., 1948. Occurrence of found in the rabbit tick Dermacentor pa- the brown dog tick in the Western States. rumapcrtus in southwestern United States. Sixth Congress Internazionale di Microbi- Journal of Economic Entomology 41 ( 1 ) 102. ologia, Sezioni VIITXVI 2 (793): 600. Lillie, R. D., 1941. Pathology of Rocky Moun- and Kohls, Glen M., 1951. Elk, winter tain spotted fever. National Institutes of ticks and Rocky Mountain spotted fever: Health Bulletin 177. U. S. Public Health a query. Public Health Reports 66-1672- Service, U. S. Government Printing Off- 1675. ice, Washington, D. C. and Parker, R. R., 1933. Rocky Mountain spotted fever. Investivation of sexual trans- Maxey, E. E., 1899. Some observations on the mission in the wood tick Dermacentor an- so-called "spotted fever" of Idaho. Medi- dersoni Public Health Reports 48 (11): cal Sentinel 7: 433-438. 266-272. Parker, R. R., 1923. Transmission of Rocky Ricketts, H. T., 1906. The study of Rocky Mountain spotted fever by the rabbit tick Mountain spotted fever (Tick fever) by Haemaphysalts leporis-palustris Packard. means of animal inoculations: a prelimi- American Journal of Tropical Medicine nary communication. Journal American 3: 39-46. Medical Association 47 (1): 33-36.

, 1934. Recent studies of tick-borne diseases , 1906. The transmission of Rocky Moun- made at the United States Public Health tain spotted fever by the bite of a wood Service laboratory at Hamilton, Montana. tick (Dermacentor occidentalis) Journal Proceedings 5th Pacific Science Congress American Medical Association 47 (5) : 358. 5: 3367-3376. , 1909. Some aspects of Rocky Mountain , 1938. Rocky Mountain spotted fever. spotted fever as shown by recent investi- American Medical Association Journal gations. Medical Record 76: 842. 110: 1185-1188, 1273. Robinson, A. A., 1908. Rocky Mountain spotted ; Kohls, Glen M. and Steinhaus, E. A., fever with report of a case. Medical Rec- 1943. Amblyoma americannums a vector ord 74 (22): 913-922. of Rocky Mountain spotted fever. Public Rucker, A. 1912. Rocky Mountain spotted Health Reports 58 (12): 491. C, fever. Public Health Reports 27 (36) ; Philip, C. B.; Davis, G. E., and Cooley, 1465-1482. R. A., 1937. Ticks of the United States in J. S., 1934. Some ectoparasites of relation to disease in man. Journal Eco- Stanford, Utah birds and mammals. Proceedings of nomic Entomology 30 (1): 51. Utah Academy of Science. Arts and Let- ; Philip, C. B. and Jelhson, W. L., 1933. ters 11: 247. Rocky Mountain spotted fever. Potenti- Stiles, C. W., 1905. zoological investigation alities of tick transmission in relation to A into the cause, transmission and source of geographical occurrence in U. S. Ameri Mountain spotted fever. Hygienic can Journal of Tropical Medicine 13 (4): Rocky 341-379. Laboratory Bulletin No. 20: 28 and 116.

, 1908. The common tick {Dermacentor ; Philip, C. B.; Davis, G. E. and Cooley, of the Bitter Root Valley. Pub- R. A., 1937. Ticks of the United States in andersoni) lic Reports 23 (27): 949. relation to disease in man. Journal of Health Economic Entomology 30 (1): 51-69. Topping, N. H., 1940-41. Rocky Mountain 64 Brigham Young University Science Bulletin

spotted fever studies. fever." First Biennial Report of the Mon- Public Health Reports 55 (2): 41-46. tana State Board of Health. PubUc Health Reports 55 (17): 728. Wolbach, S. B., 1919. Studies on Rocky Moun- Public Health Reports 56 (34): 1699-1703. tain spotted fever. Journal of Medical Re- Public Heahh Reports 56 (42): 2041-2043. search 41 (1): 1-197. Wilson, L. B. and Chowning, W. M., 1902. The Wood, M. L., 1896. Spotted fever as reported so-called "spotted fever" of the Rocky from Idaho. Report Surgeon General, U. Mountains. A preliminary report to the S. Army for 1896: 60-65. Montana State Board of Health. Journal American Medical Association 39: 131- Yeatter, R. E. and Thompson, D. H., 1952. 136. Tularemia, weather and rabbit popula- and Chowning, W. M., 1903. Report on tions. Illinois Natural History Survey Di- the investigation of the so-called "spotted vision Bulletin 25 (6): 351-382.