Mutation scanning‐based analysis of T heileria orientalis populations in cattle following an outbreak

Bovine theileriosis is a tick‐borne disease caused by one or more hemoprotozoan parasites of the genus T heileria . In the past, T heileria infection in cattle in A ustralia was largely asymptomatic and recognized to be associated with T heileria buffeli . However, outbreaks of theileriosis have occurred in beef and dairy cattle in subtropical climatic regions ( N ew S outh W ales) of A ustralia. There is also one published report of a recent theileriosis outbreak in a beef farm near S eymour in the southeastern state of V ictoria. In order to gain an improved insight into the genetic composition of T heileria populations following this outbreak, we undertook herein an integrated PCR ‐coupled mutation scanning‐sequencing‐phylogenetic analysis of sequence variation in part of the major piroplasm surface protein ( MPSP ) gene within and among samples from cattle involved in the outbreak. Theileria DNA was detected in 89.4% of 94 cattle in the S eymour farm; the genetic analysis showed that the ikeda and chitose genotypes representing the T heileria orientalis complex were detected in 75 and 4.8% of 84 infected cattle, respectively, and that mixed populations of these two genotypes were found in 20.2% of infected cattle. Given unpublished reports of a significant increase in the number of outbreaks in V ictoria, future investigations should focus sharply on elucidating the epidemiology of T heileria to subvert the economic impact on the cattle industry in this state. Although used here to explore genetic variation within the T. orientalis complex in A ustralia, a mutation scanning‐based approach has broad applicability to other species of T heileria in other countries.