Distribution and temporal prevalence of T heileria orientalis major piroplasm surface protein types in eastern A ustralian cattle herds

Objective To determine the distribution of theilerial types in eastern A ustralian cattle herds and their changing prevalence in regions of N ew S outh W ales ( NSW ). Design Survey testing of herds in 2010–11 in Queensland ( QLD ), NSW and V ictoria ( VIC ) where clinical theileriosis was not evident and ongoing surveillance in NSW through laboratory submissions. Methods Blood samples were tested by PCR targeting the T heileria orientalis p32 gene and positive tests were examined for the I keda, Chitose and Buffeli types. Survey samples from 516 cattle in 50 herds and diagnostic submissions from 434 suspect field cases in 116 herds were analysed. Results I n clinically normal survey cattle, T . orientalis prevalence was high ( NSW 23.7%, QLD 56.8%, VIC 34.0%), with variability among regions of each state. Chitose was the most common and widespread type (19.1–43.7% per state), with Buffeli present in all states at a lower prevalence (10.8–24.8% per state). I keda was detected in three of five regions in QLD ( N orth, S outh and S outh East; prevalence 3.4–15.4%), only one of the surveyed regions in NSW ( N orth Coast; prevalence 74.2%) and in only one animal in VIC . Evidence of clinical disease and laboratory confirmation of I keda infection in diagnostic submissions were predominant in several NSW regions, with increasing numbers of affected herds particularly in the coastal Mid‐Coast and Cumberland areas. Conclusions I n those regions where prior evidence of theileriosis was uncommon, I keda infection was evident in a limited number of NSW regions and multiple regions in QLD . However, clinical disease has continued to become widespread in NSW and VIC , involving I keda strains in many regions.