RESUMEN
Bovine tropical theileriosis caused by Theileria annulata is a tick-borne disease associated with high morbidity and mortality in the livestock. The conventional method of diagnosis is by the demonstration of the parasite stages by microscopic examination. This method suffers from low sensitivity, making it even more difficult to detect piroplasms in the carriers. PCR based assays are known to be more sensitive. The present study was undertaken to detect and quantify T. annulata in the blood of clinically infected and carrier animals using a quantitative PCR protocol targeting the gene encoding the major merozoite piroplasm surface antigen Tams 1. A total of 116 samples were collected from infected as well as apparently healthy cattle and buffaloes. Of these, 74 samples (63.79%) were positive for T. annulata by real-time PCR, including the 15 samples that were positive by Giemsa staining. The parasite load ranged from 1.39 x 106 to 3.35 x 109 and 0.35 x 106 to 2.83 x 107 ml-1 of blood in cattle and buffalo samples, respectively by qPCR. Our study suggests that real-time PCR assay can be used to detect and quantify the load of T. annulata in the blood of cattle and buffaloes. It also serves as a support to clinical diagnosis and assessment of carrier status in apparently healthy animals.