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TDK conference 2013

Ecological and molecular investigation of ticks and tsetse flies from Ethiopia
Duressa Getachew Abichu - year 5
SzIU, Faculty of Veterinary Science, Parasitology and Zoology
Supervisor: Sándor Hornok DVM


Tick-borne infections are recognized as emerging problems worldwide. Modern molecular biological methods, that have become recently available, allow more sensitive and specific detection of pathogens in tick species. However, most of these studies are carried out in the Western countries (Europe and USA), Australia or highly developed regions of Asia, as the molecular analyses are expensive and require not only financial resources, but equipments. As a consequence, although the majority of vector-borne infections (i.e., those transmitted by blood-sucking arthropods) occur in Africa, these are less frequently studied with up-to-date methods. The purpose of the present work was to compensate for this lack of information.

Altogether 1032 hard ticks were removed from cattle in South-Western Ethiopia in three different kinds of tick biotopes. Adults of four species/genera predominated, i.e. Amblyomma variegatum, A. cohaerens, Boophilus decoloratus and two Rhipicephalus spp. (R. evertsi and R. praetextatus). One specimen of Hyalomma rufipes male was also found, and three Amblyomma and one Boophilus nymphs. It was observed, that while the number of males and females of Rhipicephalus spp. were equilibretaed, for Amblyomma spp. males and for B. decoloratus females predominated. According to tick habitats, B. decoloratus was absent from savannah lowland; A. variegatum was significantly more abundant on mid highland, than on moist highland; whereas on savannah lowland virtually only A. cohaerens was found.

DNA was individually extracted from one specimen of both sexes of each tick species per cattle. Regarding pathogen detection in these ticks, 10% were positive for the causative agent of Q fever, Coxiella burnetii, with highest prevalence on savannah lowland. From among piroplasms, the mildly pathogenic species: Theileria mutans, T. velifera and T. orientalis were detected, with considerable sequence variation (altogether eight genotypes). In A. variegatum Babesia caballi was also demonstrated. Significanlty more A. variegatum specimens were rickettsia-positive, than in case of other tick species. On the other hand, the low level of haemoplasma positivity seemed to be equally distributed among the species.

In the same region more, than 600 tsetse flies were also collected (with traps). These belonged to four species: Glossina tachinoides, G. morsitans, G. pallidipes and G. fuscipes. Females were significantly more frequently caught. DNA was extracted from pools of tsetse flies. Six samples (all G. tachinoides) out of 162 were Rickettsia sp. positive. As rickettsia-infection was reported in G. morsitans from West-Africa, to the best of our knowledge this is the first molecular evidence of the presence of rickettsiae in G. tachinoides, and in tsetse flies of East-Africa.

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