Protozoosis of the Calf: Giardia, Cryptosporidium, Eimeria, Sarcocystis, Neospora

Protozoal parasites are ubiquitous within domestic cattle. In fact, infections of cattle with Giardia duodenalis, Cryptosporidium spp., Eimeria spp., Sarcocystis spp., and Neospora caninum are so widespread that eradication of these organisms is seldom a wise or practical goal. The good news is that practical steps are available for the prevention or reduction of clinical disease by these parasites. These organisms share several important traits. All of them have fecal-oral transmission by encysted egg-like structures that survive for prolonged periods in the environment and resist chemical disinfection. After the initial infection, these organisms cause permanent or repetitive subclinical infections that are held in check by the development of specific immunity (i.e. “premunition”). A few management practices can reduce the risk of disease from these organisms, including ingestion of high quality colostrum, reducing parasite burdens in the farm environment, protecting feedstuffs from contamination, providing good nutrition, and prophylactic or therapeutic antimicrobial therapy.