Serological investigation of ovine theileriosis by ELISA in Gannan Tibet Region of Gansu Province in China.

The Gannan Tibet Autonomous Region is the biggest and most important stock-raising region of Gansu Province, People's Republic of China. Many sheep and goats from this region suffer from Theileria challenge each year, resulting in inestimable economical losses. A first large-scale serological investigation by enzyme-linked immunosorbent assay of ovine theileriosis in this region was performed by testing a total of 1,165 sera samples collected from seven districts of three counties. The results showed that seroprevalence of reactive antibodies varied from 27.8 to 83.3%, whereby the average was 70.1% in the disease-endemic areas. Another 44 sera samples collected every month from July 2004 to June 2005 from a stable flock of sheep in Biandu Town of Lintan County were analysed to evaluate the seasonal kinetics of anti-Theileria antibodies. The results indicated that anti-Theileria antibody seroprevalence rose from March, reaching a peak value of 68.2% in May, declining in October and reaching the lowest value of 36.4% in January. The data indicate that seroprevalence of anti-Theileria antibodies correlate to the known activities of its transmitting vector and also imply that chemical therapy of animals should be performed during May to June in these Theileriosis-epidemic regions.