Coccidiosis is caused by a microscopic protozoan parasite. The parasite invades intestinal cells and destroys the cells while multiplying, causing diarrhea in the process. Coccidiosis in cattle is characterized by straining and bloody diarrhea. The organism is widespread - almost all cattle become infected at some time in their lives, although many never show signs of illness. Illness is more common in concentrated livestock operations because there is more opportunity for the environment to become contaminated in large numbers, and for calves to be exposed to large doses of the parasite.
