Background: Rhipicephalus sanguineus and Hyalomma marginatum are the most common species in sheep herds in Northeast of Iran. There is preliminary evidence that these species may be the vectors of Babesia ovis in Iran. We carried out two experiments in Mashhad area, Khorasan Razavi Province to determine whether B. ovis could be transovarially transmitted by R. sanguineus and H. marginatum.Methods: In experiment 1, adults of laboratory reared H. marginatum and R.sanguineus were infected with B. ovis isolated from naturally infected sheep in Mashhad area by feeding the ticks on the sheep inoculated intravenously by infected blood samples. The inoculated sheep showed clinical signs with parasitaemia while the adult ticks were engorging on them. The engorged females were collected and kept at 28°C and 85% relative humidity in incubator. Then, larval, nymphal and adult stages derived from engorged females were used to infest the clean sheep. In experiment 2, two splenectomized sheep were infested only with the same adult ticks of two species.Results: Examination of smears and PCR of blood samples to detect of B. ovis in infested sheep in two experiments were negative.Conclusion: It seems that R. sanguineus and H. marginatum can not transovarially transmit B. ovis in sheep
