VOL. 134, NO. 10, PL. 1 SMITHSONIAN MISCELLANEOUS COLLECTIONS SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 134, NUMBER 10 THE MEDICAL AND VETERINARY IMPORTANCE OF COCKROACHES (With Seven Plates) By LOUIS M. ROTH and EDWIN R. WILLIS Pioneering Research Division Quartermaster Research and Engineering Center Natick, Mass. (Publication 4299) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION DECEMBER 19, 1957 THE LORD BALTIMORE PRESS, INC. BALTIMORE, MD., U. S. A. FOREWORD It is rare indeed that a reviewer finds that a publication completely changes his orientation to the matter discussed. In all honesty that was the end result of reading this detailed, comprehensive, and fascinating review of the relationships, both probable and possible, of cockroaches and disease. Although the cockroach has long been the target of intensive control efforts in both the civilian and the military communities, my personal grudge against the insect has been based more on suspicion than fact. I would surmise that most physicians, like myself, have been influenced by the lack of emphasis on the disease transmission potential of the cockroach in most medical curricula. This review has corrected that deficiency. It has replaced a complacent acceptance of the insect as an unpleasant nuisance in areas of poor sanitation with a firm belief that greater attention must be placed on increased attempts to demon- strate, both in the laboratory and in the field, possible relationships between the prevalence of cockroaches and the incidences of certain diseases. Perhaps these insects have received less attention in this country than they have deserved. One could say the same for typhoid fever, smallpox, yellow fever, dengue, and malaria. The pronounced and sustained increase in the level of sanitation in the United States over the past one hundred years has relegated many diseases and disease vectors to a very low level of attention. It is only appropriate that the general medical population in this country should turn great- est attention toward problems of current domestic importance. On the other hand, the Medical Officer and related medical scientists of the Armed Forces must of necessity consider such problems in the light of conditions existing today in areas in which they may be required to serve. With complete candor I recommend this review to all who, in uniform or out, practice the art and skill of disease prevention the world over. Lt. Col. Herbert L. Ley, Jr., MC Research and Development Division, Office of The Surgeon General Department of the Army CONTENTS Page Foreword iii I. Introduction I II. The vector cockroaches: their habits, habitats, and dispersal 3 III. Viruses 16 IV. Bacteria 19 V. Fungi 25 VI. Protozoa 25 VII. Helminths 26 VIII. Allergy 28 IX. Cockroach bites 30 X. Accidental invasion of man 32 XI. Cockroaches as human food 34 XII. Cockroaches in medicine and medical folklore 35 XIII. Diseases incorrectly attributed to cockroaches 41 XIV. Cockroaches versus house flies 42 XV. Conclusions 44 Acknowledgments 47 Appendices 48 A. Viruses 49 B. Bacteria 52 C. Fungi 83 D. Protozoa 85 E. Helminths 89 References 112 Index 139 THE MEDICAL AND VETERINARY IMPORTANCE OF COCKROACHES x By LOUIS M. ROTH and EDWIN R. WILLIS Pioneering Research Division, Quartermaster Research and Engineering Center Natick, Mass. (With Seven Plates) As concerns the field of insect microbiology, we seem to have got ahead of ourselves in many respects. There has been very little effort to group our forces, so to speak, and for the most part the available knowledge and information is not properly known, organized, or appreciated. Steinhaus (1946). I. INTRODUCTION Since World War II there has been a resurgence of interest in the infectious agents transmitted by cockroaches, in the pathogens that survive experimental introduction into cockroaches, and in the dis- persal of cockroaches from sewers. We realize that it is rarely prac- ticable for investigators to scan all the pertinent literature or to bolster reports of experimental research with detailed accounts of related observations. Yet a thorough knowledge of all relevant ma- terial will always be needed in planning and evaluating future investi- gations. No previous publication has adequately summarized the background literature relating cockroaches and disease ; in fact, some of the earlier literature and some contemporary foreign publications seem to have escaped notice. For these reasons, it has seemed desir- able to survey the known relations of cockroaches to disease and to make the integrated results of the survey available for general use. Because there is a voluminous literature on the transmission of dis- ease agents by cockroaches, one might expect to find this subject well covered in current textbooks and reference books. Such is not the case. We surveyed about a dozen prominent books in the fields of 1 Part of the cost of publication of this paper was borne by the Office of the Surgeon General and the Quartermaster Research and Engineering Center, De- partment of the Army. SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 134, NO. 10 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 medical entomology, parasitology, and preventive medicine to deter- mine the extent to which this subject was covered. All the authors agreed that cockroaches are sanitarily undesirable because they are potential health hazards. Yet, generally, the subject was handled briefly and was based on only a few references. Pierce (1921) devoted a chapter to disease agents transmitted by cockroaches, in which he summarized about a dozen papers published between 1900 and 1916. Riley and Johannsen (1938) indicated that cockroaches have long been under suspicion as carriers of disease organisms; they discussed the problem in about two pages with a dozen references. Neveu-Lemaire (1938) covered the subject in about three pages with a few incomplete references (only authors' names were cited). Rosenau (1940) summed up his half-page discussion of five references : "Roaches must therefore be regarded as a sanitary menace." Dunham (1940) flatly stated, "Roaches do not transmit any disease to man." Nevertheless, he admitted in the next sentence that they might mechanically contaminate food with pathogenic or- ganisms. Herms (1939) devoted three and a half pages to cock- roaches as carriers of infectious agents but stated no definite conclu- sions (six references and original data). Chandler (1949) cited cockroaches at least eight times, as prominent transmitters of disease agents. Matheson (1950) devoted a half page to cockroaches and ". human disease but concluded, . nothing has been established of the importance of roaches in disease dissemination." Busvine (1951), in a half page, discussed the hygienic importance of cockroaches and ". concluded that . the cockroach is less likely to carry infection than the common housefly, because, though its habits are equally un- pleasant, its mobility is less." Martini (1952) devoted about three pages to cockroaches but very little to their relation to disease. Faust (1955) cited cockroaches as intermediate hosts of human helminths and mechanical vectors of several pathogenic organisms. The one current text most likely to counteract this almost universal lack of emphasis is "Insect Microbiology" by E. A. Steinhaus. Although he did not discuss cockroaches and disease as an entity, Steinhaus (1946) cited numerous instances of biologic relationships between cockroaches and micro-organisms. In addition to the textbook authors cited above, several of the authors of experimental reports have concluded that cockroaches are vectors of disease agents ; these are cited in section XV. This review is a documented summary of the tangled relations be- tween cockroaches and the organisms that cause disease in man and other animals. It directs attention to the impressive body of literature ! NO. IO COCKROACHES—ROTH AND WILLIS 3 that incriminates cockroaches as actual or potential vectors of disease agents. Undoubtedly we have overlooked some of the literature; we have eliminated some reports that were too fragmentary to form a basis for conclusions. But we have attempted to cite the significant publications. We hope that the information assembled herein will provide epi- demiologists, sanitarians, and medical entomologists with both basic knowledge and a keener appreciation of the potentialities of common cockroaches as transmitters of the agents of disease. To make the review easier to read, we have grouped the annotated lists of pathogenic organisms, naturally or experimentally associated with cockroaches, in appendices. The appendices contain the meat of our argument ; they should not be overlooked. One of my native patients in S. Rhodesia always slept in the open, as he preferred to give up his hut to the cockroaches He placed food there for them and slept outside undisturbed. Moiser (1947). II. THE VECTOR COCKROACHES: THEIR HABITS, HABITATS, AND DISPERSAL There are more than 3,500 known species of cockroaches (Rehn, J. W. H., 1951). J. A. G. Rehn (1945) estimated that less than 1 percent of the known species are domiciliary pests. However, we should point out that most species of cockroaches have never been implicated in the transmission of disease agents. The pest cock- roaches, which are all more or less closely associated with man, are the only ones of proven medical or veterinary importance. The vast majority of cockroaches are presumed to be medically harmless ; but it is well to keep in mind that, should any of these change their habits and become followers of man, they too may become as potentially dangerous as the known domiciliary species. The following cockroaches have been incriminated, naturally or experimentally, in the transmission of pathogenic agents or have been claimed to bite man. The cited common names were taken from Rehn (1945) or Sailer (1955). Scientific Name Common Name 1. Blaberus atropos (Stoll) 2. Blaberus craniifer Burmeister 3. Blaberus discoidalis Serville 4. Blaberus juscus Brunner 5. Blatta orientalis Linnaeus Oriental cockroach 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 34 Scientific Name Common Name 6. Blattella germanica (Linnaeus) German cockroach 7.