Cryptosporidium Infections in Cats and Dogs

CE Email comments/questions to [email protected], fax 800-556-3288, or log on to www.VetLearn.com Cryptosporidiosis was recognized as an important zoonosis in the early 1980s. Early studies assumed that all infections in mammals, including humans, were caused by the parasite Cryptosporidium parvum. Recent studies using molecular biologic tools and hostspecificity studies indicate that cats and dogs have their own unique species of Cryptosporidium (C. felis and C. canis, respectively). Surveys indicate that up to 38.5% of cats and up to 44.8% of dogs are infected with Cryptosporidium spp. Initial studies indicate that owning a cat or dog does not increase the risk of humans acquiring cryptosporidiosis, although human infections with C. felis and C. canis have been found in patients with AIDS, immunosuppressed patients, and children from impoverished areas. Clinical signs of cryptosporidiosis in cats and dogs vary from none to chronic or intermittent diarrhea. Fluids and other supportive measures should be used in animals with diarrhea, but there is no proven safe and effective treatment of cryptosporidiosis. AIDS, and it was later found in immunocompetent humans who had been exposed to infected dairy calves. Several groups of researchers conducted studies in which C. parvum was successfully transmitted from calves to young animals, including cats and dogs. Successful cross-species transmission studies with C. parvum led to the proposal that the organism was responsible for all infections in mammals. Most parasitologists embraced this concept, which has been taught in most veterinary schools since the 1980s. Recent studies of Cryptosporidium spp from cats, dogs, and humans indicate that these organisms are biologically and genetically different from C. parvum; thus they are now considered separate species. Cryptosporidium felis is primarily found in cats and Cryptosporidium canis in dogs; Cryptosporidium hominis is the newly recognized parasite in humans. Cryptosporidium Infections in Cats and Dogs David S. Lindsay, PhD Anne M. Zajac, DVM, PhD Virginia-Maryland Regional College of Veterinary Medicine COMPENDIUM 864 November 2004 M