An unidentified species of Theileria infective for cattle discovered in China.

Infection experiments, morphological observations and transmission experiments were conducted with an unidentified Theileria sp. isolated from a naturally infected ox. The results showed that the protozoa could multiply extensively in a splenectomized ox and the parasitaemia could reach 52.69%. The Theileria sp. was polymorphic: being pear-shaped, circular, elliptical, rod-like, comma-shaped, three-leafed- or cross-shaped and having many other irregular-shapes which were seldom detected. In erythrocytes, the anaplasma-like protozoa grew, producing protoplasm which could extend and clump together, and developed into many polymorphic protozoa. Some of the protozoa propagated themselves by budding. The protozoa could not be transmitted by Haemaphysalis longicornis or Hyalomma detritum. The pathogenicity, vector ticks and life cycle of this protozoan are unknown.