Coccidiosis is a parasitic disease of the intestinal tract of animals, caused by coccidian protozoa. The disease spreads from one animal to another by contact with infected feces, or ingestion of infected tissue. Diarrhea, which may become bloody in severe cases, is the primary symptom. Most animals infected with coccidia are asymptomatic; however, young or immuno-compromised animals may suffer severe symptoms, including death. Intestinal coccidiois occurs both in dogs and cats. Oocysts of Cystoisospora species can infect and cause asymptomatic infections in a number of hosts. Infections in humans have been reported in immuno-compromised hosts, but usually with coccidian species NOT found in dogs and cats.