Molecular detection and identification of Babesia bovis and Babesia bigemina in cattle in northern Thailand.

Although Babesia bovis and Babesia bigemina infections cause economic losses in the cattle industry in northern Thailand, there is inadequate information on Babesia isolates present in the area. Therefore, to determine the prevalence and genetic relationship between Babesia isolates, we screened 200 blood samples of cattle from Chiang Rai, Chiang Mai, and Lumpang provinces of northern Thailand. A nested polymerase chain reaction using primers targeting B. bovis spherical body protein 2 (BboSBP2) and B. bigemina rhoptry-associated protein 1a (BbiRAP-1a) genes revealed a prevalence of 12 and 21 % for B. bovis and B. bigemina, respectively, while that of mixed infections was 6.5 % samples. The prevalences of B. bovis in Chiang Rai, Chiang Mai, and Lumpang were 9.5, 3.7, and 25.5 %, respectively. For B. bigemina, the prevalences were 15.8, 12.9, and 39.2 % in Chiang Rai, Chiang Mai, and Lumpang, respectively. Mixed infections with B. bovis and B. bigemina were 6.3 % in Chiang Rai, 1.9 % in Chiang Mai, and 13.7 % in Lumpang. The identical sequences of either BboSBP2 gene or BbiRAP-1a gene were shared among the Babesia isolates in the three provinces of northern Thailand. Further analysis using the internal transcribed spacer gene revealed at least four genotypes for B. bovis and five genotypes for B. bigemina in northern Thailand, while the sequences present great genetic diversities in the different isolates. Overall, we have demonstrated a high prevalence and polymorphism of Babesia parasites in northern Thailand calling for the need to design effective control programs for bovine babesiosis.