**2.3 Pathogenesis**

Babesia spp. are a various group of tickborne, obligate, intra-erythrocytic Apicomplexan parasites infecting a wide variety of animals. Ticks are most often infected transovarially. The female tick becomes infected by the ingestion of parasites during engorgement. After it drops off the host, the babesial agents reproduce within the tick's tissues. Some of the reproducing organisms are incorporated within developing tick embryos, and the disease agents are transmitted to new hosts by the feding of ensuing tick larvae, nymphs, or adults (Zaugg, 2009).

B. bovis is the most pathogenic of the bovine Babesia. B. bigemina infections are not as virulent as those of B. bovis, however the parasites may infect 40% of the red cells (Taylor et al., 2007).

Babesia affecting small ruminants are generally less pathogenic than their bovine likes (Cebra, C., and Cebra, M., 2002a).
