Ticks and tick-borne pathogens in livestock from nomadic herds in the Somali Region, Ethiopia

Between May 2006 and January 2007, blood samples and ticks were randomly collected from 220 nomadic animals from Filtu and Dollo Odo districts, Libaan zone, in the Somali Region of Ethiopia. Overall, 81.5% cattle, 98.2% camels, 53.4% goats and 61.1% sheep were infested by ixodid ticks. Collected ticks (n = 1,036) were identified as Rhipicephalus pulchellus (40.1%), R. pravus (25.8%), Amblyomma gemma (9.4%), Hyalomma rufipes (13.3%), H. truncatum (2.8%), H. impeltatum (1.2%) and H. dromedarii (0.5%); immature stages (6.1%) belonged to the genera Rhipicephalus and Amblyomma. Tick infestation burden was evaluated by the Tick Abundance Score method on 57 animals from Dollo Odo in August 2006, and it was significantly higher in cattle and camels than in small ruminants (p < 0.001). Reverse Line Blot Hybridisation was applied to detect Theileria, Babesia, Ehrlichia and Anaplasma spp. Five out of 50 blood samples from Filtu, four from cattle and, surprisingly, one from a camel, were positive for Theileria mutans and two from cattle for T. velifera. Adult ticks (n = 104) from both districts were tested and A. gemma from cattle were positive to T. velifera (1) and Ehrlichia ruminantium (5 samples). Positive E. ruminantium samples were also tested by PCR targeting pCS20 and 16S rRNA genes and submitted to DNA sequencing. The phylogenetic reconstruction of pCS20 fragment showed the presence of the Somali region sequences in the East-South African group. Our results are the first available on ticks and selected tick-borne diseases from the Somali region of Ethiopia and could be used as preliminary information for planning sustainable control strategies for tick and tick-borne pathogens in the study area and in neighbouring areas with similar socio-ecological features.