Theileria annulata, a tick-borne intracellular protozoan parasite, causes a severe and often fatal disease in cattle in tropical and subtropical countries, where 250 million cattle are at risk of infection. The infection gives rise to a lymphoproliferative disease as the parasite subverts the signal transduction pathways of the cells (leukocytes and red blood cells) it invades. Theileriosis is typically accompanied by severe anemia. Available therapeutic treatment is effective only in the early stages of infection and vaccination is based on live parasite formulations.