Giardiasis and Cryptosporidiosis in Ruminants

Abstract

G duodenalis is one of the most common parasites found in ruminants. Most if not all ruminants become infected with G duodenalis at some point in their first few months of life. Giardiasis is chronic in ruminants, and, although it does not result in severe clinical signs, it does cause intestinal pathologic conditions that may result in malabsorption. Thus, giardiasis may be a production-limiting disease of ruminants. Studies employing molecular techniques demonstrate that the vast majority of ruminants are infected by a livestock-specific genotype of G duodenalis. Hence, although ruminants may serve as a potential reservoir for giardiasis in humans, they pose much less of a risk than was previously thought. C parvum remains an important cause of diarrhea in neonatal ruminants. Still, no treatment exists for cryptosporidiosis in North America. Recent research indicates that the parasite is much more common and important in dairy calves than in beef calves, and only young ruminants, generally less than 1 month of age, are infected with C parvum. Thus the zoonotic risk associated with C parvum infections in ruminants is limited to young animals and is easily managed. Less understood than intestinal cryptosporidiosis, abomasal cryptosporidiosis, caused by C andersoni, is an emerging disease in cattle that may have a significant impact on production in both beef and dairy cattle. In general, C andersoni infections are not common in cattle, but the prevalence can be high in some herds, and infections last months or even years. Further research is required if we are better to understand the significance of abomasal cryptosporidiosis