Molecular investigation of piroplasma infection in white yaks (Bos grunniens) in Gansu province, China

Piroplasmosis, including theileriosis and babesiosis, is a tick-borne haemoprotozoan disease responsible for huge economic losses to livestock industry. In China, the biology of piroplasms infective to cattle was well understood on the basis of pathogen isolations and molecular epidemiological surveys in the past few decades. But very limited information about the infection status of piroplasms in white yak (Bos grunniens), a semi-wild and endemic breed, has been recorded, so far. A total of 350 blood samples was collected from white yaks in 11 towns of Tianzhu Tibetan Autonomous County of Gansu province, China, during April to July 2015. The samples were tested using species-specific polymerase chain reaction (PCR) for Babesia bovis, B. bigemina, Theileria annulata, T. orientalis and T. sinensis. Positive samples were further sequenced and confirmed via sequence alignment. The results showed a high prevalence of piroplasms in the white yaks, 38.3%(134/350). Four Babesia/Theileria species were detected. The prevalences were 8.3% (B. bigemina), 7.7% (T. annulata), 9.7% (T. orientalis) and 26.0% (T. sinensis).No B. bovis-positive samples were detected. The single infections of B. bigemina, T. annulata, T. orientalis and T. sinensis were 2.3%, 2.6%, 5.1% and 16.9%, respectively. 11.4%(40/350) of these animals presented co-infections with 2 or 3 parasite species, in which 80.0% of co-infection had T. sinensis infection and no co-infections with 4 parasite species was detected. This is the first report to investigate the Babesia/Theileria infection in white yaks using molecular diagnostic method, for detection of B. bigemina, T. annulata, T. sergenti and T. sinensis. The findings also offer novel insights into the role of white yaks in Babesia/Theileria epidemiology and valuable information for the control and management of piroplasmosis in white yaks.