Borrelia theileri infection in beef and dairy cattle in Israel: molecular detection and co-infection with bovine piroplasmids

Background: Tick-borne relapsing fever is an infectious disease caused by spirochetes of the genus Borrelia, leading to fever and spirochetemia in humans and animals. Borrelia theileri is the agent of bovine relapsing fever, which is transmitted by ixodid ticks of the genus Rhipicephalus and has been reported to cause mild disease in cattle. It has been infrequently reported in several countries over a broad geographic area; however, it has not been reported in Israel previously. Methods: Blood samples were collected from beef and dairy cattle in 23 locations in Israel. Real-time and conventional PCR were used to detect Borrelia spp. and co-infection with bovine piroplasmids. PCR products were sequenced, and phylogenetic analysis of the B. theileri sequences was performed. Positive cattle were identified in a limited number of locations with no clear spatial clustering. Results: Borrelia theileri DNA was detected in 6 out of 439 (1.4%) blood samples. Of these, four were from beef and two from dairy cattle. No significant differences were found according to age (P = 0.642) and production type (P = 0.802) among the B. theileri-positive cattle. Phylogenetic analysis showed clustering of the cattle-derived isolate together with B. theileri amplified from ixodid ticks, supporting a potential transmission cycle involving cattle and Rhipicephalus spp. ticks. Theileria annulata and Babesia bigemina DNA was detected in 11 (4.1%) and one (0.4%) of 268 unvaccinated cattle, respectively. Co-infection with Theileria annulata was found in one beef and one dairy cattle. Conclusions: Tick-borne relapsing fever is present in the cattle population of Israel. Co-infection of B. theileri and bovine piroplasmids may drive clinical disease and financial losses in beef and dairy cattle. This is the first report of B. theileri infection in Israel. Future control programs should address the exposure of both beef and dairy cattle to ticks and tick-borne diseases.