Isolation of a bovine Theileria.

Dual infections of Anaplasma marginale and a Theileria, resembling Theileria mutans, occurred in splenectomized calves inoculated with pooled blood samples from eastern Texas cattle. Theileria was obtained in pure form by treating dually infected cattle with selectively eliminated Anaplasma. These theileria infections were responsible for mild, transient reductions in packed red blood cell volume (PCV).