Theileria orientalis Ikeda genotype infection associated with anaemia, abortion and death in beef cattle in Western Australia

Background Theileria orientalis infection causes a clinical syndrome in cattle characterised by weakness, reluctance to walk, anaemia, jaundice and death in peri‐parturient cows and young calves, referred to as bovine anaemia caused by Theileria orientalis group (BATOG). Abortions in pregnant cows are also reported. Pallor, pyrexia and elevated heart and respiratory rates are typical findings on physical examination. Case Report A syndrome of abortions, lethargy, inappetence, jaundice and deaths in beef cattle on two separate properties and a separate cluster of three properties within 15 km west of the town of Denmark in Western Australia was associated with the presence of severe regenerative anaemia and the presence of Theileria orientalis Ikeda genotype in blood samples taken from affected cattle and their cohorts. A diagnosis of bovine anaemia caused by the T. orientalis group was based on consistent clinical, haematological, biochemical and PCR findings. Conventional PCR testing detected only the T. orientalis Ikeda type. On the two properties where it was investigated, quantitative PCR testing for parasite load was suggestive of recent infections. Sequencing of T. orientalis major piroplasm surface protein gene PCR products demonstrated that they were identical to those from similar bovine cases in New South Wales. Conclusion The clinical history of affected cattle and the biochemical, haematological and PCR findings were consistent with bovine anaemia caused by the T. orientalis Ikeda genotype. This clinical syndrome had not been recognised in Western Australia before this series of cases.