A review of African Amblyomma species (Acari, Ixodida, Ixodidae)

This review includes descriptions of all available African Amblyomma species, keys to males and females, data on synonymy, distribution, and host-parasite associations

An overview of factors responsible for geographic distribution pattern of ixodid ticks in the Sudan

Tick fauna in the Sudan comprises over 70 species prevalent in diverse ecological zones. Among these are the most economically important ticks in Africa, namely Rhipicephalus appendiculatus, Hyalomma anatolicum, Amblyomma variegatum, Amblyomma lepidum, Rhipicephalus (Boophilus) decoloratus and Rhipicephalus (Boophilus) annulatus. Several factors determine the dynamic changes of tick distribution in the Sudan. These are animal movement either for trade, nomadism, or migration due to civil unrest etc., habitat modification such as deforestation, large-scale mechanized cultivation and urbanization; drought and desertification, and global climate change. The accelerated change in tick distribution results in outbreaks of several tick-borne diseases. Examples of these are East Coast fever, tropical theileriosis, malignant ovine theileriosis, heartwater and babesiosis by Babesia bovis. Emergence of these diseases in districts believed to be free is alarming and has adverse effects in the process of animal resources development. This communication discusses distribution patterns of the economically important livestock ticks in the Sudan and identifies new zones where ticks have established and the possible factors determining such distribution.Keywords: Distribution, Factors, Livestock, Sudan, Ticks

A survey of tick species on cattle and African buffaloes in the Tsavo Conservation Area, Kenya

The objective of this study was to compare the tick species that infest African buffaloes (Syncerus caffer) with those that infest domestic cattle in the Tsavo Conservation Area in Kenya. To this end ticks were collected from cattle and African buffaloes within the study locality. Fourteen tick species belonging to the genera Amblyomma, Hyalomma and Rhipicephalus were collected. Eight species, namely Amblyomma gemma, Amblyomma lepidum, Hyalomma albiparmatum, Hyalomma rufipes, Hyalomma truncatum, Rhipicephalus evertsi evertsi, Rhipicephalus pravus and Rhipicephalus pulchellus, were collected from cattle and from buffaloes sampled during the study period. Three species, namely Hyalomma impeltatum, Rhipicephalus humeralis and Rhipicephalus praetextatus, were present only on buffaloes, and three, Rhipicephalus (Boophilus) sp., Rhipicephalus kochi, and Rhipicephalus muehlensi, were collected only from cattle. Of all the ticks collected, those of the genus Amblyomma are associated with the highest risk of disease and possibly with severe losses in cattle in the area. New locality records for H. impeltatum and H. truncatum were determined and the first locality records for R. praetextatus sensu stricto in Kenya are reported.Dissertation (MSc)--University of Pretoria, 2011.Veterinary Tropical DiseasesMScUnrestricte

Evidence of Rickettsia and Orientia Infections Among Abattoir Workers in Djibouti.

Of 49 workers at a Djiboutian abattoir, eight (16%, 95% confidence interval [CI]: 9-29) were seropositive against spotted fever group rickettsiae (SFGR), two (4%, 95% CI: 1-14) against typhus group rickettsiae, and three (6%, 95% CI: 2-17) against orientiae. One worker (9%, 95% CI: 2-38) seroconverted against orientiae during the study period. This is the first evidence of orientiae exposure in the Horn of Africa. SFGR were also identified by polymerase chain reaction in 32 of 189 (11%, 95% CI: 8-15) tick pools from 26 of 72 (36%) cattle. Twenty-five (8%, 95% CI: 6-12) tick pools were positive for Rickettsia africae, the causative agent of African tick-bite fever. Health-care providers in Djibouti should be aware of the possibility of rickettsiae infections among patients, although further research is needed to determine the impact of these infections in the country

Influence of the biotope on the tick infestation of cattle and on the tick-borne pathogen repertoire of cattle ticks in Ethiopia

Background: The majority of vector-borne infections occur in the tropics, including Africa, but molecular eco- epidemiological studies are seldom reported from these regions. In particular, most previously published data on ticks in Ethiopia focus on species distribution, and only a few molecular studies on the occurrence of tick-borne pathogens or on ecological factors influencing these. The present study was undertaken to evaluate, if ticks collected from cattle in different Ethiopian biotopes harbour (had access to) different pathogens. Methods: In South-Western Ethiopia 1032 hard ticks were removed from cattle grazing in three kinds of tick biotopes. DNA was individually extracted from one specimen of both sexes of each tick species per cattle. These samples were molecularly analysed for the presence of tick-borne pathogens. Results: Amblyomma variegatum was significantly more abundant on mid highland, than on moist highland. Rhipicephalus decoloratus was absent from savannah lowland, where virtually only A. cohaerens was found. In the ticks Coxiella burnetii had the highest prevalence on savannah lowland. PCR positivity to Theileria spp. did not appear to depend on the biotope, but some genotypes were unique to certain tick species. Significantly more A. variegatum specimens were rickettsia-positive, than those of other tick species. The presence of rickettsiae ( R. africae ) appeared to be associated with mid highland in case of A. variegatum and A. cohaerens . The low level of haemoplasma positivity seemed to be equally distributed among the tick species, but was restricted to one biotope type. Conclusions: The tick biotope, in which cattle are grazed, will influence not only the tick burden of these hosts, but also the spectrum of pathogens in their ticks. Thus, the presence of pathogens with alternative (non-tick-borne) transmission routes, with transstadial or with transovarial transmission by ticks appeared to be associated with the biotope type, with the tick species, or both, respectively

Molecular screening for Anaplasmataceae in ticks and tsetse flies from Ethiopia

Hard ticks and tsetse flies are regarded as the most important vectors of disease agents in Sub-Saharan Africa. With the aim of screening these blood-sucking arthropods for vector-borne pathogens belonging to the family Anaplasmataceae in South-Western Ethiopia, four species of tsetse flies (collected by traps) and seven species of ixodid ticks (removed from cattle) were molecularly analysed. DNA was extracted from 296 individual ticks and from 162 individuals or pools of tsetse flies. Besides known vector–pathogen associations, in Amblyomma cohaerens ticks sequences of Anaplasma marginale and A. phagocytophilum were detected, the latter for the first time in any ticks from cattle in Africa. In addition, part of the gltA gene of Ehrlichia ruminantium was successfully amplified from tsetse flies (Glossina pallidipes). First-time identification of sequences of the above pathogens in certain tick or tsetse fly species may serve as the basis of further epidemiological and transmission studies