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New Theileria PCR

Thursday, March 5, 2020

The AHDC is now offering a PCR test for Theileria orientalis, an emerging pathogen in cattle in the US. The preferred samples are 2 ml of EDTA whole blood in a purple top tube, or spleen. Liver, kidney, and lymph node are also acceptable samples.
Theileria orientalis is a tick-borne protozoon that infects white blood cells and red blood cells and causes bovine infectious anemia. Clinical signs of theileriosis are similar to anaplasmosis in cattle, and include anemia, jaundice, and weakness. Native genotypes of T. orientalis in the US are usually nonpathogenic, but a paper published in September 2019 in Emerging Infectious Diseases first described the virulent Theileria orientalis Ikeda genotype infecting cattle in Virginia. Cattle in the index herd were simultaneously parasitized with Haemaphysalis longicornis, also known as Asian longhorned ticks. The Asian longhorned tick is a known vector of Theileria orientalis in Australia, and it was therefore presumed that this tick was the vector for theileriosis. The Asian longhorned tick, known to preferentially feed on animals, was first documented in the US in 2017.