The document discusses the life cycle, pathogenesis, diagnosis, and control of Theileria, a protozoan parasite transmitted by ticks that infects lymphocytes and red blood cells in cattle. Theileria hijacks the cell division and growth control mechanisms of lymphocytes, causing uncontrolled proliferation that transforms the cells and leads to pathology similar to lymphoma. Effective control methods include tick control, drug treatments like buparvaquone and parvaquone, and vaccination to control East Coast fever in endemic areas.