Molecular surveillance of tick-borne diseases in Iranian small ruminants

Abstract

Tick-borne diseases in small ruminants are common in temperate, subtropical and tropical countries and lead to meat and milk production losses with some diseases being zoonotic as well. However, compared to tick-borne diseases in cattle, very little is known about the pathogens and no existing molecular method allows a species-specific detection without cross-reaction for tick-borne pathogens in sheep and goats. In our study, we monitored 100 sheep and collected 89 ticks on these animals from seven different Iranian regions. The molecular surveillance of tick-borne diseases was based on polymerase chain reaction (PCR) amplification of the 16S and 18S rRNA genes. For bacteria, PCR was positive for 29.0% of blood samples and 25.8% for ticks, whereas for protozoa, PCR was positive for 76.0% and 59.5% of blood and tick samples, respectively. 93.1% and 82.6% of the bacteria-positive blood and tick samples were also positive for Piroplasmida ( Theileria and Babesia spp.) showing the opportunist behaviour of these bacteria. Sequencing results showed that sheep were infected with Anaplasma ovis and Theileria lestoquardi, and ticks from these sheep were infected with Ehrlichia ovina, Theileria lestoquardi and Theileria spp.