22/05/2022
Theileriosis
Theileriases are a group of tickborne diseases caused by theileria spp. Both theileria and babesia are members of the suborder piroplasmorina. Although babesia are primarily parasites of rbcs, theileria use, successively, wbcs and rbcs for completion of their life cycle in mammalian hosts. The infective sporozoite stage of the parasite is transmitted in the saliva of infected ticks as they feed. Sporozoites invade leukocytes and, within a few days, develop to schizonts. In the most pathogenic species of theileria (eg, t parva and t annulata), parasite multiplication occurs predominantly within the host wbcs, whereas less pathogenic species multiply mainly in rbcs. Development of the schizont stage of pathogenic theileria causes the host wbc to divide; at each cell division, the parasite also divides. Mortality in such stock is relatively low, but introduced cattle are particularly vulnerable. Unlike in babesiosis, in theileriasis there is no evidence of increased resistance in calves
