SUMMARY
Background: Small ruminants’ babesiosis caused by Babesia ovis, is transmitted during blood feeding by infected ticks and is the most economically important tick-borne disease in tropical and subtropical areas. This study was carried out to to estimate the infection rate of B. ovis in sheep and goats by PCR. We have analysed risk factors that might influence infection of sheep and goats with B. ovis.Methods: A total 402 blood samples were examined microscopically for the presence of Babesia infection. All samples were tested by PCR. During sampling, whole body of each animal and farm dogs was examined for the presence of ticks.Results: Forty-two animals (10.4%) were positive for Babesia spp. upon microscopic examination, whereas 67 animals (16.7%) yielded the specific DNA for B. ovis of which 52 animals were sheep and 15 animals were goats.Twenty-nine farms (72.5%) were found positive for B. ovis. The percentage of positive animals in each location varied from 13 % to 20 %. The relative risk of the presence of ticks in sheep and goats (P< 0.01) and farm dogs (P< 0.01) for PCRpositive results forB. ovis in sheep and goats was found 3.8 and 2.9, respectively. A total of 747 ticks identified as Rhipicephalus bursa, R. sanguineus and R. turanicus on the basis of morphological features.Conclusion: Other animal species besides dogs may also be risk factors for babesiosis in sheep and goats. Also, R. bursa may play an important role as a vector of the parasite in Iran.