Babesia bigemina and Theileria annulata infections in cattle: molecular detection, phylogenetic analysis, and assessment of risk factors.

ABSTRACT

Babesia bigemina and Theileria annulata are tick-borne protozoans that cause piroplasmosis in cattle, resulting in huge damages to the livestock industry. The prevalence of these infections depends on various intrinsic and extrinsic risk factors. In Pakistan, there is no information regarding the molecular characterization of Babesia bigemina and the risk factors associated with piroplasmosis. This study aimed to molecularly characterize Babesia spp. and Theileria spp. infecting various cattle breeds in Khyber Pakhtunkhwa, Pakistan, and to shed light on risk factors associated with these infections. Altogether, 219 blood samples were collected from various symptomatic cattle breeds, including Holstein Friesian (65.3%; 143/219), Jersey (21.5%; 47/219) and Sahiwal (13.2%; 29/219). Isolated genomic DNA from these blood samples was used in PCR for the amplification of the 18S rRNA fragment of apicomplexan parasites. Obtained 18S rDNA sequences from cattle hosts showed 99.5% identity with B. bigemina, or 100% with T. annulata. Having an overall infection rate of 61.6% (135/219), the highest infection rate was recorded for T. annulata (43.8%; 95/219), followed by B. bigemina (18.3%; 40/219). Phylogenetic analysis of 18S rDNA sequences revealed that B. bigemina clustered with corresponding species reported from Bolivia, and South Africa, while T. annulata grouped with same species from Italy, India, and Turkey. Among the different risk factors, the breed, season, and tick infestation were found to have a significant (P < 0.05) association with the piroplasmid infections. The information obtained in this study can be employed for effective surveillance and control of babesiosis and theileriosis in Pakistan. In addition to confirming our previous molecular detection of T. annulata in cattle, this study provides the first molecular surveillance and phylogenetic position of B. bigemina and associated risk factors in the study region.