Ecological and Epidemiological studies on ticks (Acari: Ixodidae) in Pibor area, Jonglei State.
By
Jacob Maiju Korok
B.V.Sc., 1995 Zagazig university, Egypt
A thesis submitted in partial fulfillment of the requirement of the University of Khartoum for the degree of Master of Veterinary science
Supervised by
Dr.Khitma Hassan ElMalik
Department of Preventive Medicine and Veterinary Public Health Faculty of Veterinary medicine University of Khartoum
March, 2005
Dedication
This thesis is dedicated with love and respect to my mother and father. To my wife Roda John and my beloved children Lena, Koma and Ngantanga.
Acknowledgement
Thanks to almighty God for blessing and strength that enabled me to produce this manuscript. Iam deeply grateful to my supervisor Dr.Khitma
Hassan ElMalik for planning research proposal, continuous encouragement, advices and sincere supervision of this work. The valuable guidance she offered has motivated me to undertake this work despite the difficult situation in the southern Sudan. My sincere gratitude to Dr.Ibrahim Ismail
Julla for great support and keen advices, his effort is really appreciated. Iam greatly indebted to Jonglei State Government for nomination to pursue my study. Iam very grateful to Central Veterinary Research Laboratory and the
Department of Ticks and Tick-borne diseases control in particular for their genuine cooperation. My special acknowledgement to Dr.Magdi Badwy and
Dr.Brony Jones for their great assistant. I appreciated the excellent cooperation of the technical staff of the Department of Preventive Medicine and Veterinary Public Health (Ahmed Abdel Wahid). Special thanks to the community members of Pibor and the surrounding villages who provided a great deal of useful information. I would like to express my gratitude to members of my family for their patience and encouragement.
Abstract This study was conducted to investigate various tick species infesting livestock in four locations in Pibor area. Seasonal distribution of ticks, population density and prevalence of tick-borne diseases were thoroughly studied with emphasis on the ecological and epidemiological background.
Ticks were collected from cattle, sheep, goat, and dog and from the pasture.
Blood smears were collected from cattle, sheep and goat for detection of tick-borne pathogens. Sera were collected from cattle to assess the prevalence of Ehrlichiosis (Cowdriosis) due to high infestation of
Ambylomma lipidium. The participatory rural appraisal tools were used to collect data on tick ecology and tick-associated health problems of livestock in Pibor area. The potential of application of these techniques were discussed. The tick species identified in the study area revealed, Ambylomma lipidium, Ambylomma vareigatum, Rhipicephalus (Boophilus) decoloratus,
Rhipicephalus (Boophilus) annulatus, Hyalomma.m.refupes, Rhipicephalus simus simus, Rhipicephalus evertsi evertsi, Rhipicephalus sanguineous. The most abundant tick species were Ambylomma lipidium 56.6%, Rhipicephalus sanguineous 20.5% and Rhipicephalus evertsi evertsi 16.2% from total collected ticks. The individual tick species identified in the present study, showed a diverse pattern of seasonal variation in response to climatic conditions that prevail in the study area. Wet season showed high tick collection (81.3%) followed by dry warm season (16.1%) and dry cold season (2.6%). Cowdriosis prevalence rate was detected by serology in sheep (37.1%) and goat (89.7%) using Enzyme Link Immunosorbent Assay
(ELISA). The study concluded some epidemiological and ecologcal parameters related to ticks and tick-borne diseases in the study area.
اﻟﺨﻼﺻﺔ
ﺗﻬﺪف هﺬﻩ اﻟﺪراﺳﺔ ﻟﻠﺒﺤﺚ ﻓﻲ ﻋﻴﻨﺎت ﻣﺘﻨﻮﻋﺔ ﻣﻦ اﻟﻘﺮاد اﻟﺘﻲ ﺗﻐﺰو اﻟﻤﺎﺷﻴﺔ ﻓﻲ ارﺑﻊ
ﻣﻮاﻗﻊ ﻓﻲ ﻣﻨﻄﻘﺔ اﻟﺒﻴﺒﻮر ﺣﻴﺚ اﺟﺮﻳﺖ دراﺳﺔ ﺷﺎﻣﻠﺔ ﻟﻜﺜﺎﻓﺔ و اﻻﻧﺘﺸﺎر اﻟﻤﻮﺳﻤﻲ ﻻﻧﻮاع
اﻟﻘﺮاد ﻣﻊ اﻟﺘﺮآﻴﺰ ﻋﻠﻰ ﺧﻠﻔﻴﺘﻬﺎ اﻟﺒﻴﺌﻴﺔ و اﻟﻮﺑﺎﺋﻴﺔ وﻗﺪ ﺗﻢ ﺟﻤﻊ ﻋﻴﻨﺎت ﻣﻨﻬﺎ ﻣﻦ اﻟﻤﺎﺷﻴﺔ و
اﻟﺨﺮاف واﻟﻤﺎﻋﺰ و اﻟﻜﻼب و اﻟﻤﺮاﻋﻲ ﺑﻴﻨﻤﺎ ﻗﻤﻨﺎ ﺑﺎﺧﺬ ﻋﻴﻨﺎت دﻣﻮﻳﺔ ﻣﻦ اﻻﺑﻘﺎر
واﻟﺨﺮاف واﻟﻤﺎﻋﺰ ﺑﻬﺪف اﻟﻜﺸﻒ ﻋﻦ اﻻﻣﺮاض اﻟﺘﻲ ﺗﺴﺒﺒﻬﺎ اﻟﻘﺮاد .وآﺎن اﻟﻐﺮض ﻣﻦ
ﺟﻤﻊ ﻣﺼﻮل اﻟﻤﺎﺷﻴﺔ هﻮ ﺗﻘﻴﻴﻢ ﻣﺪى ﺗﻔﺸﻲ ﻣﺮض(Cowdriosis)اﻟﻤﺘﺼﻠﺔ ﺑﺎﻻﻧﺘﺸﺎر
اﻟﻜﺜﻴﻒ ﻟﻠﻘﺮاد ِِ(Ambyloma lipidium) آﻤﺎ ﻧﺸﻴﺮ ﻻﺳﺘﺨﺪاﻣﻨﺎ ﻻدوات ﺗﻘﻴﻴﻢ رﻳﻔﻴﺔ ﺑﻌﺪ
اﻟﺘﺄآﺪ ﻣﻦ اﻣﻜﺎﻧﻴﺔ اﻻﺳﺘﻔﺎدة ﻣﻨﻬﺎ ﻓﻲ ﺟﻤﻊ ﻣﻌﻠﻮﻣﺎت ﻋﻦ ﺑﻴﺌﺔ اﻟﻘﺮاد و ﻣﺸﻜﻼت ﺻﺤﺔ
اﻟﺤﻴﻮان اﻟﻤﺮﺗﺒﻄﺔ ﺑﻬﺎ . و ﻗﺪ آﺸﻔﺖ ﻋﻴﻨﺎت اﻟﻘﺮاد اﻟﺘﻲ ﺗﻢ اﻟﺘﻌﺮف ﻋﻠﻴﻬﺎ ﺧﻼل اﻟﺪراﺳﺔ
ﻋﻦ Ambylomma lipidium, Ambylomma vareigatum, Rhipicephalus
(Boophilus) decoloratus, Rhipicephalus (Boophilus) annulatus,
Hyalomma.m.refupes, Rhipicephalus simus simus, Rhipicephalus
.evertsi evertsi, Rhipicephalus sanguineous. ﻟﻘﺪ ﺗﺸﻜﻠﺖ اﻟﺴﻮاد اﻻﻋﻈﻢ
ﻟﻌﻴﻨﺎت اﻟﻘﺮاد اﻟﺘﻲ ﺗﻢ ﺟﻤﻌﻬﺎ ﻣﻦ Ambyloma lipidium%56.6 و
Rhipicephalus sanguineous%20.5 و Rhipicephalus evertsi evertsi 16.2% آﻤﺎ اﻇﻬﺮت آﻞ ﻣﻦ اﻟﻌﻴﻨﺎت اﻟﺘﻲ ﺗﻢ اﻟﺘﻌﺮف ﻋﻠﻴﻬﺎ ﺧﻼل اﻟﺪراﺳﺔ
ﺑﻤﻨﺎخ ﻣﺘﻔﺮﻗﺔ ﻣﻦ اﻟﺘﺒﺎﻳﻦ اﻟﻤﻮﺳﻤﻲ ﻓﻲ ﺗﺠﺎوﺑﻪ ﻣﻊ اﻟﻈﺮوف اﻟﻤﻨﺎﺧﻴﺔ اﻟﺴﺎﺋﺪة ﻓﻲ اﻟﻤﻨﻄﻘﺔ اﻟﺘﻲ أﺟﺮﻳﺖ ﻓﻴﻬﺎ اﻟﺪراﺳﺔ ﺣﻴﺚ ﺷﻬﺪ اﻟﻔﺼﻞ اﻟﻤﻤﻄﺮ ﺗﺠﻤﻴﻊ ﻟﻠﻘﺮاد ﺑﻠﻎ81% ﻳﻠﻴﻬﺎ اﻟﻔﺼﻞ
اﻟﺤﺎر ﺟﺎف 16.1% ﺛﻢ اﻟﻔﺼﻞ اﻟﺒﺎرد اﻟﺠﺎف 2.6% ﺑﻴﻨﻤﺎ آﺎن ﺗﻔﺸﻲ ﻣﺮض ال
Cowdriosisﺑﻨﺴﺒﺔ 37.1% ﻋﻨﺪ اﻟﻀﺎن و ﺑﻨﺴﺒﺔ 89.7% ﻋﻨﺪ اﻟﻤﺎﻋﺰ وذﻟﻚ وﻓﻘﺎ
ﻟﻠﻜﺸﻒ ﺑﺎﺳﺎﻟﻴﺐ ﻋﻠﻢ اﻟﻤﺼﻮل ﺑﺎﺳﺘﺨﺪام ELISAﻋﻠﻤﺎ ﺑﺎن اﻟﺪراﺳﺔ ﺗﻮﺻﻠﺖ ﻟﻤﻌﺎﻳﻴﺮ
وﺑﺎﺋﻴﺔ ﻣﺮﺗﺒﻄﺔ ﺑﺎﻟﻘﺮاد و اﻹﻣﺮاض اﻟﻨﺎﺗﺠﺔ ﻋﻨﻬﺎ ﻓﻲ ﻣﻨﻄﻘﺔ اﻟﺪراﺳﺔ
TABLE OF CONTENTS
Page DEDICATION...... i
ACKNOWLEDGEMENTS...... ii
ABSTRACT...... iii-iv
ARABIC ABSTRACT...... v-vi Table contents...... vii List of tables ...... viii List of figures ...... ix List of plates...... x
Introduction...... 1
Chapter One: Literature review...... 3
1.1. Tick Taxonomy...... 3 1.2. Morphology...... 4
1.2.1. Family Argasidae(soft tick)...... 4
1.2.2. Family Ixodidae(hard tick)...... 5
1.3. Tick Biology ...... 5
1.4. Tick Ecology ...... 7
1.5. Tick Distribution ...... 9
1.5.1. Africa ...... 9
1.5.2. Sudan ...... 11
1.6. Economical importance of ticks ...... 14 1.7. Veterinary importance of ticks ...... 15
1.7.1. Tick-borne viral diseases ...... 16 1.7.1.1. Nairobi sheep disease ...... 16
1.7.1.2. Louping ill Disease ...... 16
1.7.2. Tick-borne bacterial disease ...... 16 1.7.2.1. Dermatophilosis ...... 16
1.7.2.2. Bovine farcy ...... 17
1.7.3. Tick-borne protozoan disease ...... 18 1.7.3.1. Theileriosis ...... 18
1.7.3.2. Babesiosis ...... 20
1.6.4. Tick-borne Rickettsial disease ...... 21 1.7.4.1. Cowdriosis(Heartwater) ...... 21
1.7.4.2. Anaplasmosis(gall sickness) ...... 22
1.7.5. Tick Toxicosis ...... 23 1.7.5.1. Sweating sickness ...... 23
1.8. Medical importance of ticks ...... 23
1.9. Ticks control ...... 25
1.9.1. Conventional tick control ...... 26
1.9.2. Ticks-killing plants ...... 28
1.9.3. Traditional methods of ticks control . . .29
1.9.4. Biological control ...... 30
1.9.4.1.Predators ...... 30
1.9.4.2. Parasitoid ...... 31 1.9.4.3. Pathogens ...... 32
1.9.5. Immunization using anti-tick vaccine. . . 33 Chapter Two: Materials and Methods ...... 35
2.1. Description of the study area ...... 35
2.1.1. Sites selected ...... 36 2.1.2. The climate ...... 36
2.1.3. Livestock population and movement . . . . 37
2.1.4. Wildlife ...... 40 2.2. Ticks collection
2.2.1. On host tick collection ...... 42
2.2.2. Off host tick collection...... 42 2.2.3. Tick identification ...... 42
2.3. Blood smear collection ...... 46
2.4. Serum collection ...... 46 2.5. Indirect ELISA protocol ...... 46
2.6. Use of participatory rural appraisal (PRA) tools in tick survey ...... 48
2.6.1. Combined Matrix ...... 48
2.6.2.Seasonal calendar ...... 48
2.6.3. Proportional piling ...... 52
2.7. Meteorological data ...... 52
2.8. Statistical analysis ...... 53
Chapter Three: Results ...... 54 3.1. Tick survey ...... 54
3.1.1. ticks collected ...... 54 3.1.2. population density ...... 54
3.1.3. Host-tick relationship ...... 59
3.1.4. Seasonal dynamic of ticks ...... 68 3.2. Participatory survey of ticks ...... 73
3.2.1. Matrix scoring results ...... 73
3.2.2. Proportional piling results in four locations ...... 76
3.3. Tick-borne diseases ...... 82
Chapter Four: Discussions ...... 85-92 Reference ...... 93-109
LIST OF TABLES
Table 1: Prevalence of adult tick species in the study area ...... 56 Table 2:Population of ticks in four locations in Pibor area ...... 57 Table 3 : Total count of ticks in different animal species ...... 61 Table 4 : Total sex count of different tick species ...... 62 Table 5 : Number of ticks collected from bovine and non-bovine ...... 65 Table 6 : Seasonal activity of ticks in the study area ...... 70 Table 7 : Survey of blood parasites diseases. . .83 Table 8 : Sero prevalence of animal species sera to Cowdriosis ...... 84
LIST OF FIGURES Fig 1: Map of Africa showing distribution of R.appendiculatus, A.variegatum and Hyalomma species ...... 13 Fig 2 : Map of Pibor area ...... 41 Fig 3 : Meteorological data during study period. .55 Fig 4 : Geographical distribution of tick samples.58 Fig 5 : Seasonal variations of ticks ...... 72 Fig 6 : Distribution of ticks among different hosts in the study area...... 64 Fig 7 : Sex distribution among the collected tick samples ...... 66 Fig 8 : Number of ticks collected from cattle in comparison with other hosts...... 67 Fig 9 : Climatic effects on tick population. . . .71 Fig 10 : Representation of combine matrix ranking tick associated health problem...... 75 Fig 11 : Ranking of livestock diseases in Manyerany ...... 77 Fig 12 : Ranking of livestock diseases in Kavachuch ...... 78 Fig 13 : Ranking of livestock diseases in Pibor town ...... 79 Fig 14 : Ranking of livestock diseases in Likongole ...... 80 Fig 15 : Overall ranking of livestock disease in the study area ...... 81
Plates Plate 1 : Cattle during dry warm season . . . . .38 Plate 2 : Sheep in the beginning of wet season. . 39 Plate 3 : Dragging blanket strip used for tick collection ...... 44 Plate 4 : Collection of ticks from pasture. . . . 45 Plate 5 : Combined matrix scoring completed by a pastoralist ...... 50 Plate 6 : proportional piling exercise conducted by cattle owners...... 51
Introduction
Ticks are important ectoparasites in tropical and sub tropical areas through direct effects of their feeding and as vectors for various agents of disease in both man and livestock. The effective control of tick-borne diseases, and changes in patterns of infection, depends on the understanding the epidemiological factors that favours the establishment of ticks and the parasites carried by them. The geographical distribution of ticks can be determined by Geographical Information System (GIS). This has been used widely in Africa (Lessard et al, 1990). In the southern Sudan, the distribution of ticks on livestock in different areas has been carried out by epidemiological survey (Morzaria et al, 1981, FAO, 1983 and Julla, 1994).
However, these studies have not covered the Pibor area. Ticks and tick- borne diseases have recently become major concerns to livestock owners in the study area which affect the livestock productivity. Moreover, the abundance of wildlife in the area may play a vital role in the epidemiology of ticks and tick-borne diseases. There are seasonal movements of livestock for pastures and water. Cattle raid within and across the country may contribute to distribution and establishment of ticks and tick-borne diseases in the area. These concerns initiated this study to fulfill the following objectives: 1. Identification of tick species prevalent in the area.
2. To study ticks ecology in Pibor area, Jonglei State and seasonal variations in their population dynamics.
3. Distribution of ticks among animal species and their relevance for general herd health.
4. To use participatory epidemiology in study of ticks population dynamics, seasonal variation and problems associated with prevalence of tick-borne diseases in the study area.
5. To help in the future strategy of control measures.
CHAPTER 1: LITERATURE REVIEW
1.1. Ticks Taxonomy:
Ticks are obligatory blood sucking external parasite of vertebrate animals, man, birds and reptiles throughout the world. There are two well established families of ticks; the Ixodidae (Hard ticks) and the Argasidae (Soft ticks).There were about 800 species and subspecies of ticks which had been identified (Kettle, 2000).
Ticks are classified according to their characteristic morphological features into:
Phylum: Arthropoda
Subphylum: Chelicerata (anterior fangs/chelicerae)
Class Arachnida: (Scorpions, Spiders, Harvestmen, and Ticks and Mites)
Order Acarina: (parasitiformes; Ticks and Mites)
Sub-order: Ixodoidea (ticks)
Family (1): Argasidae (soft ticks)
Genus: Argas, Otobius, Ornithodoros
Family (2): Ixodidae (hard ticks)
Genus: Amblyomma, Dermacentor, Hyalomma, Haemaphysalis, Ixodes,
Margropus, Rhipicphalus, and Aponoma
1.2. Morphology:
Ticks are dorso-venteral compressed and usually have no definite division between the head, thorax and abdomen. Sexes are separate. (Soulby, 1982 and Kettle, 2000).
1.2.1. Family Argasidae (Soft Ticks):
There are several species and subspecies of Argasid ticks that occur throughout most of the tropical and subtropical areas of the world
(Hoogstraal, 1956).Three genera which contain 183 species and subspecies of Argasid Ticks; Argas, Ornithodoros, and Otobius, are of Medical and
Veterinary importance (Kettle, 2000 and Horak, (2002). The Argsid ticks are characterized by leathery like conscutum; the mouth parts are situated anteriorly on the ventral surface and are not visible from the dorsal side.
Eyes are present or absent. There are two pairs of eyes situated laterally in supracoxal folds in some species of Ornithodoros. There is one pair of spiracle situated between the third and the fourth coxa. Sexual dimorphism is not marked, however; this can be differentiated by the size of the genital opening; being large in female and small in male. Male and female usually mate outside the host. Eggs are laid in several batches of hundreds and the female brood the eggs until they hatch into larvae. There are usually two or more nymphal stages. Larvae, Nymphs and adults, depending on different genera, feed repeatedly. The adult female usually lays eggs after each blood meal except in case of female Otobius which does not feed on blood. They usually infest nests, burrows and buildings and attach to sleeping hosts
(Soulby, 1982).
1.2.2. Family Ixodidae (Hard Ticks):In the Ixodid ticks, the scutum covers the entire dorsal surface in males but only part of the dorsal surface of females, this characterize them into sexual dimorphism. The mouth parts
(capitulum) project forwards and are visible from dorsal view. Larvae have three pairs of legs and Nymphs have four pairs of legs and are lacking porose areas, scutum and genital openings (Hoogstraal 1956). Scutum size remains constant during engorgement of females and thus covers a progressively smaller proportion of the dorsum. Eggs are laid in a single batch of thousands. There is only one nymphal stage. Larvae, nymphs and adults feed only once in each stage, and require at least several days to complete engorgement (Soulby, 1982 and kettle, 2000). Males usually remain longer on the host; females die a natural death after laying eggs.
1.3. Tick Biology:
The life cycle of Argasid ticks differs considerably from the Ixodid ticks.
After the blood meal, male and female Argasid ticks copulate outside the host. The female then lays eggs in small batches of hundred eggs and in a repeated process. The female broods the eggs and after they hatch into larvae, the female dies a natural physiological death. The larvae feed on blood, with the exception of Ornithodoros larvae, and then moult into nymphs. The nymphs of all Argasid ticks feed on blood and moult into adult after 2-4 nymph stages.
The life cycle of Ixodid ticks are divided according to their feeding behaviour on blood into three types.
1. One Host Ticks: Where all the three instars (Larva, Nymph, and Adults) feed on one host to complete their life cycles. Male and female copulate on host during feeding process. The engorged female, then drop to the ground to lay eggs. Eggs are laid as one batch of large quantity and the female afterwards die a natural physiological death. Examples of this type are the species of Boophilus (Walker et al, 2003).
2. Two Hosts Ticks: In this type, the larvae attach to the host, feed, engorge and moult into nymphs. The nymphs feed on the same host, engorged and drop to the ground to moult into adults. The adult male and female attach to the host and copulate during the feeding process. The engorged female drop to the ground to lay eggs and therefore die a natural death. An example of this type is Rhipicephalus evertsi and R.bursa (Kettle, 2000, Walker et al,2003).
3. Three Hosts Ticks: In this type, the larvae attach to the host feed, engorge and drop to the ground to moult into nymphs. The nymphs attach to a second host feed, engorge and drop to the ground to moult into adults. The adults male and female attach to the third host and copulate during the feeding process. The engorged females drop to the ground to lay eggs. The females after laying eggs die a natural physiological death. An example of this type of ticks are all Amblyomma species, Haemaphysalis and most Rhipicephalus and Hyalomma species (Soulby, 1982, Kettle, 2000, Walker et al,2003).
1.4. Tick Ecology:
The climatic variations are the main factors which determine the ecological and the geographical distribution of ticks. Species of ticks are adapted to a certain range of temperature and moisture. Some ticks occur only in warm regions with a fair degree of humidity, while ticks in temperate areas become most active during summer season. Changes in the climatic situation may considerably cause changes in the geographical distribution of ticks
(Kovat et al, 2001). However, ticks within their habitats experience several environmental factors such as temperature, relative humidity (RH) and rain fall. The temperature and relative humidity (RH) are the important factors which regulate the life cycle of ticks. The influence of the temperature and relative humidity on attachment of Boophilus microplus larvae on host showed the optimum temperature between 31-38c° (Doube and Kemp,
1979).However, the decrease in temperature showed a negative effect on the developmental stages of Hyalomma dromedarii in which egg incubation, larval and nymph premoulting periods and female pre-oviposition periods were prolonged with the decrease of the temperature (Ahmed et al, 1988).
This means that the temperature has strong correlation with tick activities by initiation and termination of host-seeking by individual tick. As a result, the development of ticks is directly influenced by maximum and minimum temperatures. The relative humidity, on the other hand, remains an important factor for survival of ticks by regulating the water balance and prevents dehydrations as stated by (Hassan, 2003). He also stated that, the high humidity is particularly more required for survival of Ixodid ticks than the
Argasid ticks. Ixodid ticks quickly die of desiccation when exposed to humidity below critical equilibrium values. Schulze et al (2001) found that
Ixodes scapularis tended to quest earlier and later in the day when temperatures were low and the relative humidity higher. Hence humidity plays an essential role in ticks activities and survival. Moreover, Meyer et al (2001) found that Demacentor reticulates and D.marginatus ticks compensated their water losses during the subsequent incubation at 95%RH.
Ali et al, (2003) mentioned that, different stages of H.a.anatolicum were able to take up water vapour at higher humidity and steadily lose it at lower humidity.
Rainfall is another factor which has a significant role in ticks ecology and distribution throughout the world. The effect of the rainfall on ticks challenge to their hosts was investigated at Kyle Recreational Park in
Zimbabwe (Mooring et al, 1994). They found that R.appendiculatus adult infestation on host were 2-3 times more during the high rainfall. They concluded that ticks burden on hosts are high during the wet season due to high rainfall. Vegetation also provides the shade and optimum humidity in microclimate habitats of ticks which enhancing their survival during adverse situation (Hassan, 2003).
1.5. Tick Distribution:
1.5.1. Africa
The distribution of ticks depends mainly on their adaptability to various ecological and climatic factors present in their habitat (Halpin, 1975 cited by
Sower, 2002). Ticks, within their habitats, experienced several environmental factors such as temperature, relative humidity, and rainfall. These factors play a significant role in tick distribution. Moreover, host density, host susceptibility and specificity, vegetation type and host grazing behavior are important factors of tick distribution.
In Africa, the tick distribution varies according to ecological variations in which some tick species prefer certain ecological conditions. For instance,
Ambylomma pomposum occurs in Angola, Ambylomma haebrem is widely distributed in most parts of southern Africa while Ambylomma variegatum has wide geographical distribution in Africa. The latter occurs across the continent from Senegal in West Africa into Central African Republic, southern Sudan, Ethiopia, and extends to Somalia (Walker and Olwage,
1987 and Norvel et al 1992). However, Hyalomma anatolicum anatolicum occurs in Northern Africa in a continuous belt along the Northern and North-
Eastern littoral, in areas receiving an annual rainfall of less 250 mm. Its range extends from Morocco in the West through Algeria, Tunisia and Libya to Egypt in the East, and South to Sudan (Norvel et al, 1992, and Bouatour et al, 1999).
In East Africa, tick infestation on animals is higher during the rainy season than in dry season (Punyua, and Hassan, 1992). In Kenya and Uganda,
R.appendiculatus, R.e.eversi, Ambylomma vareigatum, and Boophilus species are ticks of economic importance (Punyua et al,1991, Punyua and Hassan, 1992, and Okello et al 1999). Whereas, Ambylomma variegatum,
A.cohaeren Boophilus decoloratus, Rhipicephalus bergeoni R.e.evertsi
R.pulchulus and Hyalomma species were common ticks in Ethiopia
(Solomon et al,1998 and Mekonnen, et al 2001) .
1.5.2. Sudan
In Sudan, ticks fauna comprises 64 species and subspecies of both Argasid and Ixodid ticks. Most ticks of potential medical and veterinary importance in Ethiopian Fauna Region are found in Sudan. The distribution of these ticks is greatly influence by ecological variations, livestock, birds and wildlife movements (Hoogstraal, 1956). For instant, Hyalomma anatolicum anatolicum is distributed mainly in Central Sudan, Ambylomma vareigatum in Southern Sudan and A.lepidum is widely distributed throughout the country. In Western Sudan, and in Kordofan Region, the ecological range favours the survival of various species of ticks. Most of these ticks are common in cattle, sheep, goats, camels and equines. However, Amblyomma lipidium, A vareigatum, H.m.rufipes, B.decoloratus, B.annulatus
R.sangiuneous, and R.e.evertsi are more extensively distributed and apparently are more parasitizing cattle, sheep and goats in the grazing areas of arid and semi arid zones. On the other hand, H.impletatum and
H.dromedarii are common in arid areas parasitizing mainly camels (Osman, 1978). Darfur Region is linked to West African fauna by game and domestic animal movements. However, common ticks in Darfur are similar to those of
Kordofan.
In Southern Sudan, the bulk of work on ticks collection and identification was carried out in Equtoria Region (Hoogstraal, 1956). However, the most common ticks known in the Southern Sudan are Ambylomma lipidium,
Ambylomma variegatum, B. annulatus, B.decoloratus, H.m.rufipes,
H.truncatum, Heamophysalis leachi leachi, R.evertsi.evrtsi, R.simus.simus,
R.pravus, R.appendiculatus and R.sangiuneous (Morzaria et al, 1981, FAO,
1983 and Julla, 1994). N Fig1. Map of Africa showing distribution of R.Appendiculatus.& A.Variegatum
%UTunisia %U Morocco %U Algeria %U
%U Li by a Egy pt
%U Mauritania %U %U %U Mali Niger# Sudan # Chad Burkina Faso # # # # # # # # Nigeria # # # # # Ethiopia Ghana Central African Republic # Som al ia # # # # # # # # Som ali a Zaire # # Tanzania, United Republic of
# # # Angola # Mozambique # # Zimbabwe# # Bot sw ana # Namibia #
South Africa
%U Hyalomma species
# A.mblyomma varigatum
# R.appendiculatus
Source: Dipeolu et al, 1992 1.6. Economical Importance of Ticks:
The economic importance of ticks is based on their effect on animal productivity and cost of ticks and tick-borne Disease (TBD) control.
Tick infestation cause irritation, damage of hides and skins, and wounds which act as predisposing factor for bacterial, fungal infections, as well as myiasis where dipteral flies deposing their eggs and larvae in these wounds
(FAO report 1983). Ticks feed on blood of animals cause considerable loss of blood which may lead to anemia. It has been estimated that there is a loss of I-3ml of blood for every tick completing its life cycle on an animal.
Norval et al, (1992) stated that about 80% of the world population of 1,200 million cattle is at risk from tick and tick-borne diseases, with global losses amounting to US$ 7,000 million. Bram (1975) cited by El sower (2002) stated that 1600 million head of cattle and sheep were suffering from tick infestation world wide. Furthermore, tick and tick-borne diseases have become very significant problems in the modern production sector (Osman,
1991). Studies in Australia indicated that the total annual loss caused by ticks amounts to 5 dollars per head, or 4 percent of the gross value of cattle slaughtered in 1972/73 (FAO1983). Also the cost of tick control in Australia alone was estimated at 40 million dollars annually, of which one-third was the cost of tick control and two-third loss in production (Kettle, 2000). In Kenya, the importation of acaricides and drugs for theileriosis control reaches US$ 10 million in 1987. In Zimbabwe, the cost of ticks and Tick- borne disease control was estimated as US$ 9 million during the 1988/89
(Norval, et al 1992). In Sudan, Siddig et al (2003) reported the total loss due to an outbreak of Theileriosis in a dairy in Khartoum State to be about US$
62 thousand. However, Latif (1994) estimated the losses due to Theileria annulata in Khartoum to reach 4-6 million dollars annually. Hassan (1997) reported that feeding of Amblyomma species on the udder caused mastitis and teat damage resulting in a highly significant loss in milk yield.
Regarding teat damage Imam (1999) also found that tick damage to teat reached 19% for one quarter, 3.1% for two quarters, and 0.4% for three quarters. In Eddamer, Northern Sudan, Gamal et al (2003) reported that theileriosis in the farm reduced the expected profitability by 29% of gross profit.
1.7. Veterinary Importance of Ticks:
Ticks infestations on their specific hosts and at their favorable predilection sites in the presence of pathogens which are capable of being transmitted between hosts and these ticks will result in disease condition known as
“Tick-borne Diseases”. These pathogens can be bacteria, viruses, rickettsia and protozoa. Moreover, the ticks feeding behavior secrete toxin which cause “Ticks Toxicosis and Ticks Paralysis”.
1.7.1. Tick-borne viral diseases:
1.7.1.1. Nairobi sheep disease
Nairobi sheep disease is most pathogenic and a severe disease of sheep and goats in which mortality may reach 90%. It is transmitted trans-staidly and trans-ovarian by Ixodid tick, Rhipicephalus appendiculatus. It is characterized by gastroenteritis and paralysis, which in many cases lead to death of the animal (Davies, 1997 and kettle, 2000).
In Sudan, Osman, (1997) suspected the occurrence of the disease in southern
Sudan bordering, Zaire, Uganda, and Kenya.
1.7.1.2. Louping ill
Louping ill is an acute encephalomyelitis affecting mainly sheep, but other animals can also be infected. It is a viral disease transmitted by the ticks of species Ixodes ricinus. The disease is characterized by fever, abnormal gait, convulsion, and paralysis (Blood and Radostits, 1990, Sheahan et al, 2002).
The disease is present in southern Europe and northern Africa.
1.6.2. Tick-borne bacterial diseases:
1.7.2.1. Dermatophilosis: Dermatophilosis is an acute, sub acute or chronic disease affecting wide- range of animal species. It is world wide distributed but more prevalent in the humid, tropics and sub tropics (Zaria, 1993). It is caused by Dermatophilus congolensis. Feeding of Ambylomma vareigatum ticks on cattle suppress immunity such that any infection with
Dermatophilus congolensis bacteria in the skin is aggravated to cause very severe Dermatophilosis(Latiff and Walker,2004). In Kenya it has generally been found in the main semi-arid camel rearing areas (Gito, 1993). Similarly in Sudan the disease was reported in Butana region of eastern Sudan affecting camels (Gito et al, 1998). Dermatophilosis is widely recognized in the Sudan.
1.7.2.2. Bovine farcy:
Bovine farcy is a chronic infectious disease of cattle, in some tropical countries. It is considered as one of the most important mycobacterial infection (Timony et al, 1988). The disease was believed to be caused by
Nocordia farcinica, but now Mycobacterium farcinogenes and
Mycobacterium senegalense were found to be the main causitive agents
(Chamoiseau, 1979). The disease clinically shows nodular swelling of lymphatic nodes present at the sites of the attachment of the vector tick
Amblyomma variegatum (Blood and Radostits, 1990).
In Sudan, Awad and Karib,(1958) reported the relationship between Bovine farcy and Tuberculosis. The disease was found to be 14.6% in condemned carcases in Malakal Abattoir (Awad and Karib, 1958). El-Nasri (1961) noticed the spread of the disease by 15% among Arab herds in the Nuba mountains region. Nonetheless, the disease caused losses among Bargara nomadic tribe cattle in western Sudan (Hamid, 1988, El Hissien, 2001).
Recently vaccine development trial against the Bovine farcy was conducted by Eiman,(2003).
1.7.3. Tick-borne Protozoan Diseases
1.7.3.1. Theileriosis
Theileriosis is caused by a group of protozoan parasites of genus Theileria.
There are several species of theileria that infect cattle (Theileria annulata,
T.parva, T.mutans, T.velifera,T.sergenti, T.taurotragi and T. orientalis). The most pathogenic and economically important are Theileria parva, causative agent of East coast fever and Theileria annulata the causative agent of
Bovine Tropical Theileriosis or Mediterranean Coast fever (Fujisaki et al,
1994). East Coast fever is transmitted by its efficient tick vectors
Rhipicephalus appendiculatus and R. zambiziensis. On the other hand,
Bovine tropical Theileriosis is transmitted by its efficient vector tick,
Hylomma anatolicum anatolicum.
The other species of Theileria are of low pathogencity and generally cause mild infection. However, their presence complicates the epidemiology of Theileriosis in cattle. Theileria velifera cause begnin Theileriosis while
T.sergenti and T.oreintalis are mostly non pathogenic (Uilenberg, 1981).
Theileria species which infect sheep and goats are Theileria lestoquardi causing malignant Theileriosis and Theileria ovis which cause begnin
Theileiosis. Ovine or Caprine Theileriosis are both transmitted by their efficient tick vectors Hylomma anatolicum anatolicum. In Sudan,
Theileriosis caused by Theileria parva in southern Sudan where as
T.annulata and T.lestoquardi are found in the northern Sudan. East Coast fever in southern Sudan was first reported in Kajukaji and Yei River District bordering Uganda (Hoogstraal, 1956). Preliminary epidemiological studies were carried out (Morzaria et al, 1981) and confirmed the presence of ECF and its tick vector R.appendiculatus in Chukudum and Aswa River area near
Nimule. In 1982, antibodies of T.parva were detected in cattle in Bahrel
Ghazal Region with complete absence of R.appendiculatus (Zessin and
Bauman, 1982).Outbreaks were reported in Palotaka area bordering Uganda with mortality rate between 80-100%. The extents of the disease to Juba and
Terekaka (60 Km. North of Juba) indicated that the disease become established in these areas (Julla, 1985, Julla, 1994, Julla, 2003 and Julla et al, 1989). Bovine Tropical Theileriosis had been reported from different areas in northern Sudan (Shommien, 1976, 1977, Latiff and Hassan, 1982, FAO, 1983, Hassan, 1987,Siddig, 2002, Bakhiet, et al, 2002, and Salih,
2003). Moreover, Theileria lestoquardi was reported in Red sea State in eastern Sudan (Mahmmed and Salih, 2003).
1.7.3.2. Babesiosis
Babesiosis is a tick-borne protozoan disease, caused by parasite of genus
Babesia. Several species of Babesia affect cattle, sheep, goats, equine, dogs, and cats causing haemolytic anaemia, jaundice and haemoglobinuria (Red water). It is transmitted by various species of Ixodid ticks of which
Boophilus annulatus, B.decoloratus and B.microplus are predominant tick victors. The parasite is transmitted by tick through transovarian transmission and by trans-stadial in the two-host tick R.e.evertsi (Hall, 1985). Death usually occurs within 24 hours. Surviving animals remain carriers for variable periods of time (Kettle, 2000). Pre-immunity occurs, in most
Babesia species, after recovering from natural infection (Blood, et al, 1990).
Little is known about the incidence of babesiosis among the indigenous breeds of cattle in Sudan. So far, there are only two species of Babesia which had been recorded in Sudanese cattle; these are Babesia bovis and
Babesia bigemina (Abdulla, 1984). An outbreak of Babesiosis due to
Babesia bovis was reported at Sagadi area of Blue Nile State in 1979 (FAO,
1983). Later, several incidences of Babesiosis were reported in the same area (Jongejan, 1987). In addition to that Mohammed et al, (1990) reported outbreaks of Babesiosis in domestic livestock in the eastern region of the
Sudan.
1.7.4. Ricketsial diseases
1.7.4.1. Cowdriosis (Heartwater):
Cowdriosis is a tick-borne ricketsial disease of cattle, sheep, goats and other wild ruminants. The disease is one of the most devastating livestock disease in sub-saharan Africa (Collin et al, 2003, Deem, 1998) and cause considerable economic losses of domestic livestock. The causative agent is a
Cowdria ruminantum, which is transmitted by ticks of the genus
Amblyomma (FAO 1983, Sumption, 1996). The main symptoms of
Cowdriosis include fever, nervous manifestation and respiratory distress.
Hydrothorax and hydropericardim are the main postmortem lesions, hence the name heart water (Blood, 1990, Yunker, 1996). In Sudan, isolation and identification of Cowdria ruminantum were co-related to the vector ticks
Ambylomma lipidum (Karrar1960, 1963, 1965 and 1968, Musa et al. 1996, and Abdel Wahab et al. 1998). The epizootiogy of the disease was widely studied (Abdel Rahim and Shommien, 1978a, 1978b,
Shommien and Abdel Rahim 1977a, 1977b, Jongejan et al, 1984, El Amin et al, 1987, Abdel Rahim et al, 2003). 1.7.4.2. Anaplasmosis (Gall sickness)
Anaplasmosis is a tick-borne disease of cattle, sheep and goats caused by a
Ricketsial organism, Anaplasma species. There are two species of
Anaplasma, A. margile, which is pathogenic and A.centrale that cause mild infection. The organism appears with Giemsa stain as a dense bluish-purple homogenous structure within erythrocytes near the margin or centre of the cell respectively (Imam,1999). The pathogenic Anaplasmosis in cattle causes severe anemia and jaundice. Calves are relatively resistant to infection, however, cattle more than 3 years old suffer per acute condition which usually leads to death within 24 hours(Kettle,2000). Anaplasma marginale can be transmitted by twenty species of ticks of which Boophilus ticks are considered to be the most significant vector (FAO,1983 and
Blood,1990). Mechanical transmission through biting flies such as Tabanus
(Horse flies), Stomoxys (Stable flies), Clucidae (Mosquitoes) and contaminated instruments (Ristic,1968 and De Wall,2000) was reported. The clinical symptoms of Anaplasmosis include rise in body temperature, anemia and jaundice. Post-mortem lesions showed enlarged spleen, liver and distended gall bladder hence the name gall sickness(Hall,1985).
Hematological studies in Khartoum showed evidence of bovine Anaplasmosis by serology using indirect fluorescent antibody test (Suliman and Elmalik,2003).
1.7.5. Tick Toxicosis
1.7.5.1. Sweating sickness
The disease affects cattle especially the young calves infested with
Hyalomma truncatum adult ticks (Dollan, 1980). It is characterized by moist eczema and pale mucous membrane. It is common during the hot- wet season and in areas associated with heavy rainfall where the vector ticks are abundant (El Sower, 2002).
The disease has no specific treatment. However, the administration of hyper- immune serum obtained from animals which have recovered from the disease will induce immunity against the infection this method is impractical due to possible serum contamination and availability of the donor animals
(Spickett et al, 1991).
Other tick Toxicosis include tick paralysis, which result from toxins that are secreted by several species of ticks such as Ixodes rubicundus,R.evrtsi,
Haemaphysalis punctata and Ixodes ricinus (Doube, 1975, Blood, 1990).
1.8. Medical Importance of Ticks:
There is no evidence that human being act as specific host for certain species of ticks. Tick infestations on human being are mainly accidental, where ticks feed on human blood in order to complete their life cycle. However, ticks infestations on human have resulted in development of host – parasite relationship.
Ticks carry a wide range of organisms that potentially can cause diseases in human. Ticks biologically have complex interactions with microorganisms with their vertebrate hosts (Wilson, 2002). There are several species of ticks which are capable of transmitting different pathogens to humans.
Ixodid ticks are involved in the transmission of arboviruses to humans including tick-borne encephalitis, Crimean-congo haemorrhagic fever, and
Kyasanur forest disease. They transmit Lyme disease, a borrelosis of human,
Tularaemia, Rocky mountain spotted fever, and other ricketsial diseases
(Kettle, 2000). Human Tick-borne Diseases have become increasingly and well recognized in the United States of America as public health problems.
Human Babesiosis is emerging as an illness of public health significance in the United States. Its occurrence had been reported during summer in
Coastal areas in the North Eastern United States (Miester, 1999,Cable et al,2003). On the other hand, Dworkin et al, (1998) reported 133 confirmed and 49 probable cases of tick-borne relapsing fever in the North Western
United States and South Western Canada. Sigal (1999) recommended the use of vaccines to prevent Lyme disease and other human tick-borne diseases. Coker et al, (2000) have suggested vaccination, treatment, and health education in prevention and control of tick-borne zoonoses in human.
In Europe, Topolovec et al,( 2003), serologically detected rickettsiosis, lyme disease, human Babesiosis, and granulocytic ehrlichiosis in individuals with a history of tick bite from three counties in Eastern Croatia. In Africa,
Horak, (2002) reported 558 Ixodid ticks belonged to 20 species in six genera feeding on 194 humans in South Africa. The effect of tick-borne relapsing fever on pregnant women in Tanzania was investigated among 137 pregnant women and 120 non pregnant women infected with tick-borne relapsing fever. The study concluded that the risk of premature delivery during tick- borne relapsing fever was 58% with prenatal mortality of 436 per 1000 birth.
Total pregnancy loss, including abortions, was 475 per 1000 birth. The relapse rate was 3.6% in pregnant women and 1.7% in controls (Jongen et al, 1997). Moreover, tick-borne relapsing fever caused high mortality and morbidity rates among children in central Tanzania (Talbert et al, 1998).
In Sudan, the incidence of human Babesiosis was reported in Sennar. It was found that 20 out of 137 of examined patients were suspected to be suffering from Babesiosis (Suliman et al, 1998).
1.9. Ticks Control
Ticks control progrmme, in many countries aims at reduction of the tick burdens on animals by periodic dipping or spraying using acaricides.
Complete eradication of ticks is extremely difficult because of persistence of ticks, especially multi-host ticks, on wild fauna, and ability of adults to live for very long period apart from host.
Tick control is necessary for improvement of animal and achievement of animal production (Moran et al, 1990). The prospect of the ticks control measures have been and are still receiving much attention of many scientists, researchers and policy makers concerned with livestock development all over the world (Ochi,2004).
1.9.1. Conventional tick control
The conventional method of controlling ticks is by application of chemical acaricides using dip tank, spray race, hand spray, pour on and tick grease.
Generally the use of acaricides has been successful; this is possible through correct mixing of the acaricides and strategic application of ticks control measures, considering seasonal variations (Chizyuka et al, 1990). As a matter of fact, acaricides are essential in short-term but do not offer permanent solution to ticks control (Frisch, 1999). The use of cattle dip involves the animals plunging into and swimming through dip tanks or vats containing an aqueous emulsion, suspension or solution of acaricides
(Soulby, 1982, Norval, et al, 1992). Complete or almost complete immersions of cattle during dipping ensure adequate exposure of ticks to acaricides. For dipping to be effective and applicable, tick species need to be identified. The interval between dipping varies from one host tick, two host tick and three host ticks. One host tick requires 2-5weeks interval while two- three host ticks required 5-7days (Sower, 2002). Arsenic compound, the first effective method for controlling ticks and tick-borne diseases, were used in many parts of the world for over 50 years before resistance to chemical became a problem. However, acaricides such as organophosphate, organo-chlorine and synthetic pyrethroid have recently been used in a wide range (Awumbil, 1996, and George, 2000). Other conventional methods include, spray race which is also effective for ticks’ control, but the spraying equipment is subjected to mechanical failure and blockage, making this method less dependable. Moreover, it needs electric power which increases the expenses. Hand spray usually effective in small number of animals.
Controlling ticks at specific sites such as the ears or perineum can be achieved by using spot treatment of acaricides (tick grease). Pour on is also effective in ticks control. It is applied by pour of the acaricides in a strip along the length of the back of animal to get spread allover body to kill the ticks and to prevent the newly attached ticks. (Norval, et al, 1992).
Ivemectin injection has shown to be an effective against internal and external parasites. As a result it is also used, to some extent for control of ticks.
The disadvantages of chemical acaricides include development of resistance of ticks to various acaricides, environmental pollution and toxicity to man and animal. However, application of integrated ticks and tick-borne diseases control is a more suitable approach for controlling ticks and tick-borne diseases. The method is economically affordable, sustainable and environmentally friendly (Hassan, 2003).
1.9.2. Tick-killing Plants:
Tick-killing Plants contribute significantly in ticks control and reducing their populations. In South America, molasses grass(Melinus minutiflora) had been shown to reduce tick survival, but the effect was small and low(Thompson et al, 1978). Legumes of the genus Stylosanthes had been reported to be tick-killing plants (Sutherst et al, 1982). The plants are covered with glandular trichomes or hair which secretes a viscous fluid in which tick larvae become trapped and die; the plants also produce a vapour that is toxic to larvae. Norval etal,(1983b) study had shown that tick larvae avoid the sticky stems of these plants and, if given a choice, will climb the stem of another plant in preference. Preparations of Capsicum species, E. obovalifolia, S.Incanum and F.brchypoda were found to have 30-100% killing effects(Regassa,2000). He concluded that trials of these preparations were conducted using indigenous Bos indicus cattle naturally infested with ticks. Results indicate that treatment at the rate of once per day for 5days consecutively with latexes of E.obovalifolia and E.brachypoda can reduce tick burdens by up to 70% on cattle. On the other hand, Muna et al (2003) reported that dipping of eggs of Argas persicus in different concentrations of Neem(Azadirachta indica )seed kernel oil and seed kernel water extract was found to decrease egg hatchability.
1.8.3. Traditional methods of ticks control
The traditional methods of ticks control include, grass burning, hand removal of the ticks, extracts of leaves and cattle dusting with ash, are largely used in Africa. The practice of hand-deticking has been a method of tick control. Its regularity is however, not uniform, being undertaken almost daily by pastoralist households and irregular in agro- pastoral farming where the practice can be neglected totally during crop planting and harvesting seasons (Dipeolu et al,1992).
Habitat modification such as vegetation management as well as burning and heavy grazing(Imam,1999) can likely contribute to ticks control by reducing ticks population. Moreover, pasture spelling has significant role in killing of ticks by isolating them from their hosts and starving death (Hassan,1997). In western Ethiopia juices of crushed leaves of phytolaca,dodecandra, vernonina amygdalina, and crushed seed of lepidium sativum mixed with fresh cattle faeces, were used to control ticks (Regassa,2000). The variety of traditional practices maintained within different ethnic groups provides an indication of the potential usefulness of this neglected knowledge for livestock husbandry (Mesfin,et al,1994).
1.8.4. Biological control of ticks:
The biological control of ticks mainly relies on natural enemies, both predacious and parasitoid or pathogens. In nature, many bacteria, fungi, beatles, rodents, ants, birds, and other living things are feeding largely on insects including ticks. This indirectly reduces ticks population (Hoogstraal,
1956, Mwangi et al, 1991, Samish et al, 1999, Samish et al, 2001).
1.8.4.1. Predators:
Predators are most important enemies of ticks, birds are being the most effective predators. Chickens had shown essential role in ticks control, keeping flocks of them close with cattle reduce tick population (Hassan et al,
1991, Hassan et al, 1992, Dreyer et al, 1997). Red –billed Oxpeckers and yellow-billed Oxpeckers (Norval et al, 1992) have contributed in ticks control by feeding on a great amount of ticks which resulted in reduction of ticks’ population. Attempts have been made to re-introduce Oxpeckers to certain areas in South Africa. Re-introduction of Oxpeckers to farming areas was facilitated by reduced acaricide usage and availability of acaricide such as amitraz which do not poison birds (Bezuidenhout and Stutterheim, 1980).
However, the value of Oxpeckers to farmers is still disputed as the birds are known to feed on and exacerbate wounds.
Other predators that have been reported to feed on ticks are ants (Hoogstraal,
1956, Wilkison, 1970, Butter et al,1979), shrews (Short and Norval, 1982), lizards (Norval and McCosker, 1982), rodents (Maywald, 1987), and spiders
(Mwangi et al, 1991). Unlike Oxpeckers these predators feed on ticks in an opportunistic manner and it is unlikely that they would ever have a marked effect on tick abundance (Norval, 1992).
1.8.4.2. Parasitoids:
Parasitoids comprise a variety of parasitic organisms that infect different species of ticks. Smith and Cole, (1943) cited by Imam,(1999) reported that the parasitoids attack ticks either on ground or during feeding on the animals. The female parasitoid lay eggs in the host tick by piercing the integument with her ovipositor. Engorged adult female of R.appendiculatus and Boophilus species(Short et al,1989) were occasionally parasitized by the larvae of an identified species of coffin fly(Phoridae:Diptra). The parasitoids such as wasp Ixodiphagus hookeri have been used in biological control of ticks. They lay their eggs on the nymphs of A.variegatum which eventually destruct the life cycle of this tick (Mwangi et al,1997). However, trials were conducted to allow the wasp infect other tick species but result was not successful .It is indicated that this wasp is specific for of
A.variegatum (Hassan, 2003).
1.9.4.3. Pathogens:
Pathogens involve the use of certain type of Fungi, Rickettsia, Protozoa and
Bacteria in tick control. Results of some isolates of the fungi Metarhizium anisopliae and Beauveria bassiana have been proved to be pathogens for the ticks , their effects lead to death of ticks and minimize their population level of subsequent generation(Samish et al,1999,Kaya et al,1996,Kaya et al,2000, Bittencourt,2000). Ricketsial pathogen, Ricketsial prowazeki was used to artificially infect females of D.marginatum and D. albipictus
(Rehacek,1965). Wolbachia persicus is Rickettsia which was successfully put into the gut of Ornithodoros moubata where it multiplied and had damaging effect (weyer, 1973). Nevertheless, Hendry and Rechav,(1981) were able to produce the described clinical signs by injecting common laboratory strains of bacteria species Salmonella marcescens, Klebsiella pneumonia, Proteus species, Staphylococcus aureus and Pseudomonas aeruginosa into healthy engorged females of Boophilus decoloratus. They concluded that ticks become infected with bacteria after detachment from the host; despite the acaricidal action of certain bacteria, they see little prospect for their use as biological control. Entomopathogenic nematodes
(EPNs) are lethal to ticks even though they do not use their normal propagation cycle within tick’s cadavers (Samish et al, 2000).
Steinemematid and heterorhabditid are used to control insect pest economically important including ticks (Samish andGlazer, 2001).
1.9.5. Immunization using anti-tick vaccine
The principle of immunization against tick is based on identification of polypeptides antigens extracted from ticks and used as vaccines. These
Polypeptides are isolated from mid gut of ticks. The vaccine produced is a recombinant Bm86 antigen derived from the mid gut of Boophilus microplus
(Rodriquez et al, 1995). This vaccine causes damage of gut wall resulting in leakage of bovine erythrocyte in haemolymph. Ingestion of blood containing antibody to Bm86 causes lysis of the gut cells of the ticks. This results in high mortality of feeding ticks, reduction of engorged weight and egg laying capacity causing reduction of tick’s population (Hassan 2003). The vaccine is able to control Boophilus microplus and other Boophilus species (Fragoso, et al 1998, Kalafa-Allah, 1999, Pipano et al, 2003). Moreover, it is utilized in vaccination against other ticks species Hyalomma a.anatolicum and
Hyalomma dromedarii (De vos S et al, 2001).
This vaccine is now applied on a large scale against the tick Boophilus microplus in Australia since 1996. In Sudan, the vaccine is currently been evaluated against Hyalomma a.anatolicum and Hyalomma dromedarii
(Hassan, 2003). Rabbit immunity against Hyalomma a.anatolicum using larval antigens was proved (Ochi, 2004).
Chapter Two: Material and Methods
2.1. Description of the study area
Pibor area is part of Jonglei State situated at the North-East corner of the
State. The area is about 17,120 square kilometers and 200 kilometers distance to the South-East of Bor town, the capital of the State. It lies between latitude(6°-8°N) longitude(32°-34°E). The soil is mainly black cotton type with sandy penetrations. The vegetation cover is open grassland and acacia trees. The whole area is intercepted by numerous seasonal streams, which make it difficult to move during the rainy season, however, they provide excellent pastures and water resources for livestock.
The area is inhabited by Murle tribe, who live along Rivers of Pibor,
Kengen, Lotilla, and Veveno. The community is an agro-pastoralist which relies heavily on cattle and other livestock for their social and economic well-being.
The area is divided into several localities ( Fig 2) Likongole villages along the Pibor River from Manytakar to Nyergany, Gumurok ,villages along
Veveno River and on the North bank of Lotilla River, Fertet (villages along the South-East bank of the Lotilla River and Kengen River) and Pibor
(villages around Pibor town). These localities constitute the study area.
2.1.2. Sites selected:
Four locations (Pibor, Kavachuch, Manyerany and Likongole) were selected to carry out a survey on population and seasonal variation of ticks. The selection was based on:
• These areas are highly populated with livestock
• During the rainy season they constitute a refuge for animals which
move out of areas that are otherwise not accessible.
Ticks were collected randomly from the herds that were not practicing tick control programme using acaricides and from the pasture during dry warm, wet and dry cold season.
2.1.3. The Climate:
Pibor area enjoys tropical climate, with fairly high temperatures throughout the year. The mean ambient temperature is 30c° . The maximum temperature is 40c° reached in April and the minimum is 20c° in December and January.
The high temperature has importance consequences, in that it heats the moist air, uplifting it to the atmosphere, encourage evapo-transpiration that may result in heavy rainfall.
The climate is divided conventionally into three distinct seasons, the dry warm season (Feb-April), the wet season (May- November) and the dry cold season (December-January). During the study period meteorological data of the area was recoded.
2.1.4. Livestock population and movement
The livestock population in the area was estimated at one million head of cattle, 200.000 sheep and 400.000 goats(Local veterinary office). All are indigenous breeds of limited productivity. Cattle are raised mainly for milk, meat, dowry and for trade. However, sheep and goat support household every day- life economy. Seasonal movement of the livestock varies from location to another. Cattle in Pibor remain along the Pibor River North of
Pibor town during the wet season(Plate 2). In the dry season, these cattle cross Pibor River into Kong Kong for grazing(Plate 1), thereafter; they proceed to Jum for better pastures. The cattle from west Pibor move eastwards to the Kengen River and then proceed to Baath to come in contact with Fertet cattle. The traditional management system of cattle in the study area is by keeping cattle in fenced yard constructed from thorn trees during the night to avoid the wild carnivores , cattle are grazed all the day , calves are tied down and only released during milking times. The stables are cleaned daily, the dry cows dung are burned over night as insect repellent, and cattle particularly the calves are dusted with cow dung as ticks repellent
(personal observation).
Plate 1: Cattle grazing during dry season
Plate 2: Sheep in beginning of wet season grazing near Pibor river
The veterinary services in the area are provided by government, NGOs and private sector. This includes routine vaccination of cattle against major infectious and contagious diseases such as Contagious Bovine
Pleuropneumonia, Haemorrhagic Septicemia, Black quarter and Rinder pest.
Ticks and tick-borne diseases have recently become a major concern to livestock owners in the study area. There is no contingency plan from government to find means of tackling this problem. As a result ticks infestation and tick-borne diseases are increasing (Local veterinary authority).
2.1.5. Wildlife
Within the study there is Boma game reserve with a wide variety of wildlife.
The dominant species are White eared cobs(Kobus kob leucotis), Buffalo
(Syncerus caffer), Roan antelope(Hipotragus equines), Giraffe(Giraffa camelopardalis), hartebeast(Alcelaphus buselaphus), Zebra (Equus burchelli), Bohor reedbuck(Redunca redunca), Grant gazelle(Gazella granti), lion(Pathera leo), Leopard(Panthera pardus), elephant(Loxodonta
Africana), and White colobus(Colobus guereza). The movement of this wildlife depends mainly on availability of water and grazing area.
Fig. (2) PiborPibor AreaArea MapMap
Akobov N
Likongole v Ko ng ko ng R iv er
Ab os e R iv er
Manyirony v Pipor v
Kavachach v v Fertet
ke n g en R iv e r
Gumorok v
r e iv R s u io v n e L V o li l la R iv e r
PACE-Sudan, Dr. Hanan Yousif M. A. October 2004
2.2. Tick Collection
2.2.1. On host tick collection:
Ticks were collected from cattle, sheep, goats and dogs. The chosen animal was restrained and total body ticks were collected using a forceps. Attention was exerted to predilection sites of different tick species such as, briskets, dewlap, perineal region, udder, hump, inner hind legs, eyes and tail. All ticks collected were preserved in 70% Ethanol labeled with reference number, date, host and the locality.
2.2.2. Off host tick collection (pasture):
Off host ticks were collected from pasture using dragging strips of blanket as described by Norval, (1992). The dragging blanket is fixed on a one meter broom handle and is cut into 10 equal strips. It was used by dragging 20 meters distance over an area of 400 square meters at forwards and backwards direction. The stretch was applied four times over the grass to cover the defined area. The attached ticks were collected and preserved in
70% Ethanol for identification. This work was done in three locations at different occasions(Plate3 and 4).
2.2.3. Tick identification
In the laboratory, each tick collection was sorted out in 70% Ethanol and labeled. Each specimen was examined under stereoscopic dissescting microscope and the identification was carried out using taxonomic key to
Ixodid tick (Hoogstraal, 1956, Jane, 1970 and Walker et al,2003).
Plate 3: Dragging blanket strips used for tick collection on pasture
Plate 4: Dragging blanket strips used for tick collection
(admiring ticks attached on the blanked)
2.3. Blood smear collection A total of 130 male and female animals were sampled in the study area. Four age groups were sampled at one year, 1-2years, 2-4 year and 4 year. Thin blood smears were collected from the ear veins of cattle, sheep and goats for detection of tick-borne disease pathogen in study area. A drop of blood was taken on a clean glass slide, spread by another slide at an acute angle, air dried and fixed in absolute methanol for 3-4 minutes. The slide were labeled and kept in a slide box. In the laboratory, the smears were stained in 10%
Giemsa for 45 minute, washed in running water, air dried and examined under oil immersion microscope.
2.4. Serum collections:
Sera were collected from cattle, sheep and goats. Blood were withdrawn from jugular vein using vacutainer tubes without EDTA. It is allowed to clot at room temperature. Sera were separated using sterile pipette and kept in
5ml bijou bottles and stored at -20c° in deep freezer until used.
2.5. Serology
2.5.1. Indirect ELISA MAP-1B protocol:
The test was used to detect Cowdria antibodies from different animal species cattle, sheep and goat.
The test was performed as described by Van Vliet et al, (1995). MAP-1B antigen was diluted at rate 1:1000 in coating buffer of 0.5 M (sodium carbonate/sodium bicarbonate (pH 9.5) and 100µ1 were delivered onto 96 well flat bottomed polystyrene plate incubated at 37c° for 1 hour and subsequently overnight at 4c°. The coating buffer was removed and the plates were rinsed 3 times using washing buffer (PBS pH 7.2+ 0.1% Tween
20) and subsequently blocked for 15 minutes at 37c° 200µ1 blocking buffer
PBSTM(PBS pH 7.2 +0.1% Tween 20 +1%skimmed milk). Plates were then washed (PBST) three times using 100µ1 of washing buffer. Diluted test sera
(1:200) in PBSTM were applied in duplicate in appropriate wells and incubated for 1 hour at 37c° . The plates were then washed and incubated with 100µ1 of a second antibody, anti-sheep, anti-goat and anti-bovine conjugate with horse perxiodase diluted in PBS-TM (1:1000) and incubated for another 1 hour at 37c°.. After washing with PBS/T, 100µ1 OPD substrate were added to each well. Colour development was measured after 30 minutes incubation at room temperature in the dark. The reaction was stopped by adding sulphuric acid using 100µ1 well. Optical density (OD) was read at 492 nm on an ELISA plate reader. Positive and negative control sera were included on each plate in duplicate. The cut off point was calculated as average of optical density (OD) of negative control sera
(mean+3SD).
2.6. Use of participatory Rural Appraisal (PRA) tools for tick survey: In order to obtain information on community perception on ticks and tick- borne disease participatory rural appraisal methodologies were conducted.
PRA tools described as combined matrix and seasonal calendar (Catley and
Ahmed, 1996, Catley et al, 2001). These techniques were adapted in the study area as a ranking method for tick associated problems.
2.6.1. Combined matrix:
Matrix scoring was used to investigate the relationship between different types of ticks and ticks associated problems of livestock. Participants were asked to name the most important problems associated with tick infestation and these were then written in local language onto pieces of cards. The cards were placed side by side on the ground and a column of pre-prepared tick diagram at right angles. Participants then scored against the different types of ticks using stones. Each participant was asked to use 20 stones(Plate 5and
6).
2.6.2. Seasonal Calendar:
Seasonal calendar was used to collect information on seasonal variations of tick populations. Diagrams of different species of common ticks were prepared and placed on the ground beside objects representing the three seasons. The participants were asked to use 20 stones for each type of tick and divide them according to tick populations in each season. The result of this technique showed the seasonal variation of each tick species present in the area.
Plate 5: Combined matrix scoring completed by a pastoralist
Plate 6: Proportional piling exercise conducted by cattle owners
2.6.3. Proportional piling:
This technique was mainly used in Rinder pest disease search using checklist as described by (Mariner and Roeder, 2003). In this study, the technique was used to determine the importance of tick-borne diseases in comparison to other livestock diseases.
41 groups of livestock owners were interviewed using proportional piling.
The group varied from 4-10 individuals. The livestock owners were asked to rank the most common diseases in their respective locations according to their importance using a pile score. They were also asked to score against the five diseases by dividing a pile of 20 stones among them. After each disease has been scored, the livestock owners were asked to check their scores and agreed that their scores were correct. Local names of the diseases were allowed and later these names were related to scientific names after cross check of the clinical signs of a particular disease. The resultant scores were used to interpret the most common diseases prevalence in area and importance of tick-borne diseases were realized.
2.8. Meteorological data:
Temperature, relative humidity and rainfall were recorded on monthly basis to determine their effect on tick population in the study area.
2.9. Statistical analysis:
Results of tick collections and identification from animals and pasture in four locations were subjected to analysis of variance using the SPSS package
Chapter Three: Results
3.1. Ticks survey
3.1.1. Ticks collected: Out of the total 2173 ticks collected, 8 different tick species were identified.
They belong to three genera Ambylomma, Hyalomma, Rhipicephalus as illustrated in Table 1. The three most abundant tick species were
Ambylomma lipidium 54.6%, Rhipicephalus sanguineous 20.5%,
Rhipicephalus evertsi 16.2%. Other tick species found in decreasing order of prevalence were Rhipicephalus simus.simus 4.6%, Hyalomma m.refupes
3.9%, Boophilus decoloratus 1%, Boophilus annulatus 1% and Ambylomma vareigatum 1%.
3.1.2. Population density:
The mean total tick population per animal in the four locations is illustrated in Table (2). The highest tick was recorded in Pibor (1178), Manyerany
(663) and Kavachuch (263). However, Likongole was least infested area
(71) ticks. The geographical distribution and population density of individual tick species in the four locations are shown in Fig 4. Fig 3 showed meteorological data collected in the study area which had a great effect on ticks distribution in Pibor area.
Fig. 3: Metereological data recorded during study period (2003
180
160
140
120
100 Temp. RH% 80 Rainfall
60
40
20
0 Jan Feb March April May June July Aug Sept Oct Nov Dec Months
Table 1: Prevalence of adult tick species in the study area
Species Frequency Percent
R. simus.simus 100 4.6
R. sanguineus 445 20.5
A. Lepidum 1186 54.6
R.e.evertsi 353 16.2
B. annulatus 2 .1
H.m.rufipes 84 3.9
B. decoloratus 2 .1
A. vareigatum 1 .0
Total 2173 100.0
Table 2: Population of tick within four locations in Pibor area
Location Pibor Kavachuch Manyerany Likongole
Species No. Percent No. Percent No. Percent No. Percent
R. simus.simus 88 4 1 0.4 11 .5 0 0
R. sanguineus 329 15.1 9 .4 97 4.5 10 .5
A. Lepidum 569 26.2 200 9.2 379 17.4 38 1.7
R.e.evertsi 179 8.2 24 1.1 141 6.5 9 .4
B. annulatus 2 .1 0 0 0 0 0 0
H.m.rufipes 8 .4 28 1.3 34 1.6 14 .6
B. decoloratus 0 0 1 .04 1 .04 0 0
A. vareigatum 1 .04 0 0 0 0 0 0
Total 1176 54.1 263 12.1 663 30.5 71 3.3
P. value .0001
Fig. 4: Geographical distribution of the study tick samples
60
50
40
% 30
20
10
0 Pibor Kavachuch Manyerany Likogole Locations
3.1.3. Host-tick relationship: Identified tick species collected from cattle, sheep, goats and dogs and from pasture are illustrated in Table (3) Ambylomma lepidium, Rhipicephalus sanguineous, Rhipicephalus evertsi, Rhipicephalus simus.simus,
Hyalomma.m.rufipes, Boophilus decoloratus, Boophilus annulatus, and
Ambylomma vareigatum.
Total count of different tick species showed that Ambylomma lipidium was actively distributed among the hosts with relative preference to cattle. Other ticks widely differ on host specificity. For instant, Rhipicephalus simus.simus had a tendency to specificity on dogs and limited infestation on cattle and sheep but was not found in goats. Moreover, Rhipicephalus sanguineous had a significant distribution in dogs and sheep with restricted presence in cattle and goats. On the other hand, Boophilus decoloratus was seldom found on hosts other than sheep. Similarly Boophilus annulatus was not active among different host species as it was on goats. Ambylomma vareigatum was collected from cattle alone and Hyalomma.m.rufipes was found predominantly on cattle with minor presence on goats. The distribution of these tick species on hosts are illustrated in (Fig 6). The findings of sex distribution among collected tick samples reflected that male ticks represented 74.6% from total collected ticks where as female represented 25.4% (Fig 7).
Among animal species, it is quite clear that the cattle were highly infested
53% with different tick species than other animals which represented by
47% (Fig 8). Total sex count of individual tick species is illustrated in
(Table 4).
Table 3: Total count of ticks on different species
Host On posture Goat Sheep Cattle Done
Species No. Percent No. Percent No. Percent No. Percent No. percent
R. simus.simus 48 2.2 0 0 10 .5 11 .5 31 1.4
R. sanguineus 3 .1 94 4.3 159 7.3 66 3 123 5.7
A. Lepidum 0 0 68 3.1 163 7.5 947 43.6 8 .4
R.e.evertsi 0 0 170 7.8 140 6.4 43 2 0 0
B. annulatus 0 0 2 .1 0 0 0 0 0 0
H.m.rufipes 0 0 1 .04 0 0 83 3.8 0 0
B. decoloratus 0 0 0 0 1 .04 1 .04 0 0
A. vareigatum 0 0 0 0 0 0 1 .04 0 0
Total 51 2.3 335 15.4 473 21.8 1152 53 162 7.5
P. value .0001
Table 4: Total sex count of different tick species
Sex Male Female
Species No. Percent No. Percent
R. simus.simus 55 2.5 45 2.1
R. sanguineus 304 14 141 6.5
A. Lepidum 953 43.9 233 10.7
R.e.evertsi 247 11.4 106 4.9
B. annulatus 2 .1 0 0
H.m.rufipes 57 2.6 27 1.2
B. decoloratus 1 0.4 1 0.4
A. vareigatum 1 0.4 0 0
Total 1620 74.6 553 25.4
P. value .0001
Two tick species Rhipicephalus simus.simus and Rhipicephalus sanguineous were collected from pasture by using dragging blanket strip. This collection was only achieved in wet season in which the activity of ticks was very high.
Most of the tick species Ambylomma lepidium, Rhipicephalus evertsi,
Rhipicephalus evertsi, Boophilus decoloratus, Boophilus annulatus and
Ambylomma vareigatum showed negative activities on pasture that reflected availability of specific host for individual tick species. As shown in (Table
5), different tick species tend to infest bovine more than other non-bovine animal species (sheep, goats and dogs) and pasture.
Fig. 6: Distribution of ticks among different hosts in study area
60
50
40
% 30
20
10
0 On pasture Goat Sheep Cattle Dog Hosts
Table5: Number of ticks collected from bovine and non-bovine
Host Non-bovine Cattle
Species No. Percent No. Percent
R. simus.simus 89 4.1 11 .5
R. sanguineus 379 17.4 66 3
A. Lepidum 239 11 947 43.6
R.e.evertsi 310 14.3 43 2
B. annulatus 2 .1 0 0
H.m.rufipes 1 .04 83 3.8
B. decoloratus 1 0.4 1 0.4
A. vareigatum 0 0 1 .04
Total 1021 47 1152 53
P. value .0001
Fig. 7: Sex distribution among the study tick samples
female 25.4%
male 74.6%
Fig. 8: Number of adult ticks collected from cattle in comparison with other hosts
Other hosts 47%
Cattle 53%
3.1.4. Seasonal dynamic of ticks:
The individual tick species identified in the present study showed a diverse pattern of seasonal dynamic in response to climatic conditions throughout the year. Population density of some species was considerably increased during the wet season while other tick species were more prevalent during the dry warm season. The climatic effect on tick population is illustrated in
(Fig 9) which shows influence of ambient temperature, relative humidity and monthly rainfall on the population density of different tick species. Thus ticks prevalence reached their peak in September and October when rainfall and relative humidity are increased to the maximum level. ( Fig 5) shows seasonal activity of ticks throughout the year in which wet season representing 81.3%, dry warm season 16.1% and dry cool season 2.6%.
Seasonal variation of ticks is illustrated in table (6) in which individual tick species showed variety of its seasonal activities. Ambylomma Lepidum, male and female were predominant in all seasons, reached peak in wet season with considerable activity in dry warm season and dry cold season.
Rhipicephalus simus.simus occurred in wet season from May-November and showed absence in dry cold season. There was, however, a tendency for the tick to be prevalent on the hosts during dry warm season. Rhipicephalus evertsi evertsi, a two-host tick, was present throughout the year, but with indication of seasonal peak in wet season. Hyalomma.m.rufipes, there was disappearance of this tick in dry cold season and showed respective activities in wet and dry warm season. On the other hand, there was remarkable activity of Rhipicephalus sanguineous all over the year with considerable increase during the wet season.
Rhipicephalus and Boophilus species were less numerous and showed little or no seasonal variation. General collection data indicated that these species were present significantly in wet and dry warm seasons. Ambylomma vareigatum was not active throughout the year except minor prevalent in the beginning of the wet season (May).
Table 6: Seasonal activity of ticks in the study area
Seasons Wet season Dry cold season Dry warm season
Species No. Percent No. Percent No. Percent
R. simus.simus 90 4.1 0 0 10 .5%
R. sanguineus 385 17.7 33 1.5 27 1.2
A. Lepidum 1005 46.2 11 .5% 170 7.8
R.e.evertsi 245 11.3 13 .6 95 4.4
B. annulatus 2 .1 0 0 0 0
H.m.rufipes 38 1.7 0 0 46 2.1
B. decoloratus 1 .04 0 0 1 .04
A. vareigatum 1 .04 0 0 0 0
Total 1767 81.3 57 2.6 349 16.1
P. value .0001
Fig. 9: Climatic effects on tick population
180
160
140
120
Tick population 100 Max. temp RH% 80
Prevalence Rainfall 60
40
20
0 Jan Feb March April May June July Aug Sept Oct Nov Dec months
Fig. 5: Seasonal variation of ticks
Dry warm season 16.1%
Dry cold season 2.6%
Wet season 81.3%
3.2. Participatory survey of ticks using PRA tools:
The results obtained from the PRA exercises are presented in the form of copies of diagrams produced by herders, using local language. The diagrams were coped as accurate as possible in order to ensure faithful reproduction of diagram from the ground to paper.
3.2.1. Combined matrix scoring:
The combined matrix scoring produced by cattle keepers is shown in (Fig
10). Tick associated problems, in order of importance, were teat damage, lameness, skin damage, and tick- borne diseases. These problems were scored according to different genus of ticks. Ambylomma species was considered to be the main cause of teat damage with skin damage.
Hyalomma species was scored as the main cause of tick paralysis where as
Rhipicephalus species were associated with lameness . Regarding tick-borne diseases, they were not apparently known to the herders because their clinical signs were not clear like other diseases to the cattle owner. So after good probing, they concluded that all tick species Hyalomma, Rhipicephalus and Ambylomma contributed to some extent in the spread of some tick-borne diseases in Pibor area.
The seasonal calendar component of this combined matrix gave information on tick populations. The three genera mentioned were present throughout the year but numbers Ambylomma lepidium and Rhipicephalus evertsi species increased during dry warm season, with maximum numbers occurring in the wet season. This survey indicated that Ambylomma lepidium and
Rhipicephalus evertsi group peaked in the rainy season where as other tick species Hyalomma m.rufipes, R.simus. simus and R.sangiuneous distributed considerably through seasons of the year.
Fig. 10: Representation of combine matrix ranking tick associated problems
60
50
40 Hyalomma spp Ambylomma spp Ricipicephalus spp 30
20
Number Stones of scored 10
0 Teat damage Tick paralysis Lameness Skin damage Tick-borne disease Tick associated problems
3.2.2. Results of proportional piling in four different locations:
All results were put together and percentage for each disease scored was calculated to obtain the overall ranking of disease in a particular area as illustrated in Fig 11 , Fig 12, Fig 13 and Fig 14. In this participatory study the tick-borne diseases were not mentioned in three locations Pibor,
Manyerany and Kavachuch, however, it was mentioned by Likongole herders. Furthermore, there were no distinguished clinical signs known to cattle keepers to enable them to differentiate tick-borne diseases among other infectious diseases.
Fig 15 shows overall ranking of diseases in which tick- borne diseases representing 4%, FMD 26%, CBPP 17%, Trypanomiasis 4%, H.S 23%,
Fascioliasis 13% and Rinderpest 2%.
Fig. 11: Ranking of livestock disease in Manyerany
250
200
150
100
50
0 FMD (1) CBPP (3) Tryps (4) fascioliasis (5) H.S (2)
Fig. 12: Ranking of the livestock diseases in Kavachuch
80
70
60
50
40
30 20
10
0 FMD(1) Tryps(4) H.S(2) Fascioliasis(3) CBP(5) RP(6)
Fig. 13: Ranking of livestock diseases in Pibor town
450
400
350
300
250
200
150
100
50
0 FMD(1) Tryps(3) H.S(2) RP(6) CBPP(4) Fascioliasis(5)
Fig. 14: Ranking of livestock diseases in Likongole
350
300
250
200
150
100
50
0 FMD (1) CBPP(3) Trupa(5) Tick-borne H.S(2) Fascioliasis(4) diseases(5)
Fig. 15: Overall ranking of diseases in Pibor area (stones used 3930)
Tick-borne RP(6) diseases(5) 2% 4%
Fascioliasis FMD(1) 13% 26%
H.S(2) 23% CBPP(3) 17%
Tryps(4) 15%
3.3. Tick-borne diseases:
The results of 123 sera collected from cattle, sheep and goat tested by indirect ELISA MAP-IB for antibodies detection for Cowdriosis, showed prevalence of Cowdriosis in Pibor area. Sera collected from Sheep and goat revealed the detection of Heartwater antibodies. However, cattle sera indicated sero-negative to Cowdriosis antibodies.
The blood smears collected from the cattle showed Babesia species.
Table 7. Survey of bovine blood parasite
Anaplasma No. of Theileria spp. Babesia spp. Area spp. samples No. Percent No. Percent No. Percent
Pibor 54 -v -v 2 3.7 -v -v
Kavachuch 31 -v -v -v -v -v -v
Manyerany 25 -v -v -v -v -v -v
Likongole 20 -v -v -v -v -v -v
Total 130
Table 8. Sero-prevalence of animal species sera to Cowdriosis
Positive Host No. of samples No. Percent
Sheep 35 13 37.1%
Goat 39 35 89.7%
Cattle 49 -v -v
Total 123
Chapter Four: Discussion
Ticks, are generally regarded as ectoparasites that cause the greatest economic losses to livestock production in the world (FAO, 1983). They are the most dominant pest distributed throughout with various intensities. Their economic impact varies with degree of damage they cause and diseases they transmit to livestock. Various tick species have been identified in different parts of Sudan (Hoogstraal,1956, Karrar,1963). Moreover, the ecological distribution of the tick species has been reported in Darfur(Osman,1978),
Kordofan (Osman,1982), Blue and White Nile (Jongejan et al, 1987), Kosti
(Imam,1999) and South Kordofan (El Sower,2002). On the other hand, there is little information available regarding ticks and tick-borne diseases in southern Sudan particularly Pibor area. Besides there was no systematic research undertaken in this field. The counts of ticks on livestock under natural conditions without control measures are useful for studying host- parasite relations and the seasonal variations in tick population (Solomon et al, 1998). The present investigation concluded the presence of eight tick species infesting livestock in four selected locations in Pibor area. The tick species identified Table (1) was similar to those reported from Chukudum and Juba (Morzaria et al, 1982, Julla, 1994) in southern Sudan. However, in this ticks study Rhipicephalus appendiculatus was not found, this is a tick of high rainfall areas. Under normal circumstances it does not tolerate daily maxima in excess of 30° or dry seasons more than 4 months (Morzaria et al,1982), conditions not found during the year in Pibor. Also during collections of the ticks in selected four locations, no presence of
Rhipicephalus pravus despite the fact that the climatic conditions of Pibor area are more less similar to that of Koepeta which favours establishment of
Rhipicephalus pravus( Hoogstraal, 1956, Julla, 1994).
The population density of the current identified tick species in four selected locations Table (2) was variable. The highest tick count was recorded in
Pibor and the lowest tick was recorded at Likongole. The tick variations might be attributed to management system, livestock population density, vegetation cover and livestock movement from different parts to Pibor for trade purposes. Nevertheless, it is a cross point of the wildlife during their migration period from South West to Eastern part could probably increase tick infestations on the livestock.
It can also be correlated with microclimatic conditions that prevailed in the study area. The distribution of ticks in the four selected locations showed remarkable diverse pattern. The majority of ticks identified were almost present in all four locations. However, some tick species were extremely higher in a particular place and low in other locations. For instance, Boophilus annulatus and Ambylomma vareigatum were prevalent in Pibor with complete absence in Likongole, Kavachuch and Manyerany. In addition to that Rhipicephalus simus simus, the glossy tick was present also in Pibor without showing any activity in other locations. It is a tick of regions with savanna climate, widely distributed in the moderate to high rainfall regions
(Walker et al, 2003). The activity of Boophilus decoloratus was confined to
Kavachuch. This may be attributed to vegetation cover and favourable environmental conditions. Distribution of Ambylomma lepidium in Sudan is generally concentrated on the eastern part of the country from Torit and
Koepoeta in the South and as far as in Kassala State in the North (Osman et al, 2003). In the present study this tick was found to be considerably distributed in the four selected locations dominating 54.6% from total count of ticks. According to Walker et al,( 2003), Ambylomma lepidium, occurs in a wide variety of climatic regions, from temperate, to savanna and desert, but it most commonly inhabits arid habitats with 250-500mm rainfall. Also
Siddig, (2002), pointed out that the vegetation cover and water vapour at swamps provide a suitable microhabitat for the tick to survive the adverse conditions. Within the study area the Ambylomma lipidium was widely infesting animal species (cattle, sheep, goats and dogs) Table 3, but was not dragged from pasture. This does not indicate its absence on pasture, but it can occur or reappear in favourable climatic conditions. Other tick species have significant distribution in four selected locations. This investigation indicated that the tick species are influenced by various climatic factors.
There is a considerable variation in the abundance of different tick species with ecological changes. Furthermore, additional variation can be expected within any one ecological habitat with fluctuations in host density and annual rainfall (Pegram et al, 1986). This variation was correlated with the microclimatic and meteorological conditions that prevailed in the study area.
Therefore, there was remarkable geographical distribution of different tick species in four locations that indicate the presence and absence of individual tick species in specific location. The seasonal variation of ticks throughout the year revealed that wet season was dominating ticks activity by 81.3% where as in warm dry season it was 16.1% and cold dry season was 2.6%
Fig 5. Therefore, there was correlation between tick burdens on animal species and maximum level of the rainfall. The relative abundance of each tick in each season are shown in Table 6. Results of this study showed that
Ambylomma lipidium was present throughout the year with indication of seasonal peak in wet season. The prevalence of Ambylomma lepidium during rainy season is of significance to epidemiology of heartwater infection.
Incidence of this disease is expected to be high in the study area. Boophilus species were seen on cattle during wet month and at the end of dry warm season. On the other hand, Ambylomma variegatum was occasionally found on cattle in the beginning of rainy season. The Kennel tick, Rhipicephalus sanguineous has denser population during wet season and considerable numbers in warm dry season. It is a tick of warm and moist climates and is sparse in desert climate (Hoogstraal,1956, Walker et al, 2003).
Rhipicephalus evertsi evertsi are generally distributed throughout the year with considerable increase in the wet season. This tick being found in humid and hot dry environment at approximately similar number throughout the year, usually with no clear seasonal peaks (FAO,1983). Some species were numerous during wet season (R.simus simus) or in highest temperature
(Hyalomma.m.rufipes). However, disappearance of any tick species from pasture or animal in certain period does not mean its absence, but it can quickly come out or reappear during favourable climatic conditions. The presence of Rhipicephalus simus.simus and Rhipicephalus sanguineous has given strong evidence that they were apparently active in wet season seeking for available host.
The participatory study showed that PRA technique can be used to collect useful information on tick distribution and tick associated health problems in livestock. Livestock keepers fully participated in the PRA exercises and were keen to discuss ticks and tick related issues. The construction of diagrams encouraged herders to re-evaluate their own understanding of tick problems and enable them to demonstrate seasonal variation in tick population (seasonal calendar), and scoring ticks and tick associated health problems relative to one another (Fig 10). Pastoralists distinguished between the important tick species and genera, and they possessed relevant knowledge on local seasonal tick populations. The high agreement between informant groups indicated that the matrix scoring method was valuable in differentiating tick problems. Regarding the validity of the results produced by matrix scoring, the information given was genuine and similar to modern veterinary knowledge. For instant, informant groups considered Ambylomma species to be the main cause of teat damage, this evidence supported the findings of Imam, (1999). Based on results of participatory survey obtained from four selected locations (Fig 11,12,13and 14), it is quite clear that the cattle owners are not oriented about tick-borne diseases (TBDs), that was shown in diseases ranking in which the tick-borne diseases covered 4% from overall ranking of the livestock diseases (Fig 15). This indicated that there was no complete awareness about tick-borne disease among cattle keepers in the study area. 64.8% serum samples collected from sheep and goats were tested positive to
Cowdria ruminantum antibodies. The prevalence varied between those two animal species, positive cases in goat 89.7% and sheep 13%. The disease is transmitted by Ambylomma lipidium in Eastern Sudan and Blue Nile (Karrar,
1960, Jongejan et al, 1984) while Ambylomma vareigatum was incriminated as the vector in Western Sudan (Abdel Wahab et al, 1998). The sera were collected from healthy animals infested with Ambylomma lepidium and this high prevalence rate may indicate stable existence of heartwater in the study area. On the other hand, blood smears sampled from cattle showed 3% positive to Babesia species. This situation needs further investigations through extensive surveillance studies encompassing serological and parasitological survey to verify the prevalence of Babesiosis and Theileriosis in the area.
The cattle owners in the study area are not aware of conventional methods of tick control (Dip tank, spray race, and pour on), which had never been used in their areas. Mostly they apply traditional way of tick control using hand removal of ticks. Some herders adapted traditional methods of minimizing tick burdens on cattle by using urine being applied in all parts of animal body, then animal was groomed with ash allover the body (Personal observation). After one or two days ticks gradually drop off host and cattle become partially free from ticks. This method does not eliminate all ticks in the animal body but plays very crucial role in minimizing tick burden on a host. Therefore, extensive extensions services to livestock owners with regard to the importance of ticks, the economic benefit of control programme and the efficient ways of control should be considered to control ticks and tick-borne diseases in the area. Epidemiological studies of ticks as threats to livestock production should be conducted in the near future in order to contain the risk of ticks and tick-borne diseases in Pibor area.
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