Coccidiosis

Abstract

Coccidiosis in cattle is caused by protozoan parasites of the genus Eimeria. Numerous species of coccidia have been described from cattle, but only Eimeria bovis and Eimeria zuernii produce the severe clinical disease. Coccidiosis is found wherever cattle are present. The disease occurs most often in calves less than a year old, but may also occur in older cattle. Cattle become infected by oral ingestion of sporulated oocysts contained in fecal-contaminated feed or water. The severity of the disease varies from mild when only a slight diarrhea is present, to acute when the calf may die. Typical signs of coccidiosis include bloody diarrhea, straining during defecation (tenesmus), dehydration, rough hair coat, lack of appetite (anorexia), weakness, listlessness, and emaciation; sometimes convulsive seizures occur. Lesions of coccidiosis are caused by the sexual stages and include destruction of the epithelial mucosa in the large intestine. Diagnosis of coccidiosis is made on the basis of clinical signs, presence of oocysts of the pathogenic species in the feces, and history of the individual calf and herd. Several available drugs are effective for prophylaxis, but are not efficacious once signs of infection are present. The disease can often be prevented by proper sanitation and management of the calves.