Development of a Specific PCR Assay for Theileria sp. Yokoyama and Assessment of Its Potential to Cause Anemia in Cattle

The clinical implications of <i>Theileria</i> sp. Yokoyama, a recently identified <i>Theileria</i> species in cattle, remain uncertain. The objective of the present study was to evaluate the anemia status in cattle infected with <i>Theileria</i> sp. Yokoyama. Blood samples were collected from 206 cattle across seven Veterinary Ranges in Sri Lanka and analyzed for red blood cell (RBC) indices, including hemoglobin concentration, hematocrit, and RBC counts. Additionally, DNA was extracted from the samples and screened with a newly developed <i>Theileria</i> sp. Yokoyama-specific PCR assay targeting the cytochrome b gene. The PCR results revealed that 60 (29.1%) of the surveyed cattle tested positive for <i>Theileria</i> sp. Yokoyama, with 47 (78.3%) of them being co-infected with other hemopathogen species. Our findings revealed that the cattle breeds, management systems, and tick infestations are potential risk factors for the <i>Theileria</i> sp. Yokoyama infection. Next, we evaluated the anemia status among the surveyed cattle based on the RBC indices. We found that all non-infected cattle were non-anemic. By contrast, anemia was observed in 15 <i>Theileria</i> sp. Yokoyama-infected cattle, including 3 singly infected (anemia rate 3/13, 23.1%) and 12 co-infected cattle (12/47, 25.5%). Our findings suggest that <i>Theileria</i> sp. Yokoyama causes anemia in infected cattle.