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Cattle producers have been losing young calves to coccidiosis this spring. Coccidiosis is an intestinal disease that affects several animal species. In cattle it may produce clinical symptoms in animals 3 weeks to 1 year old, but it can infect all age groups.

Coccidia are a protozoan parasite with the ability to multiply rapidly and cause clinical disease. They shouldn’t be confused with cryptosporidia, a protozoan parasite affecting cattle. Cryptosporidia can be a cause of newborn-calf diarrhea and often is a co-infection with bacterial or viral infections of the small intestine.

Cryptosporidia infections can result in human infections, so people need to be conscious of sanitation when dealing with scouring calves. Coccidia are host-specific. Only cattle coccidia will cause disease in cattle. Other species-specific coccidia will not cause disease in cattle.

Rapid multiplication of the parasite in the intestinal wall and the subsequent rupture of the cells in the intestinal lining cause the majority of the damage in calves with coccidiosis. Several stages of multiplication occur before the final stage when the oocyst — egg — is passed in feces. Oocysts are extremely resistant to environmental stress and are difficult to remove from the environment completely. Oocysts must undergo a final process called sporulation before they are infective again. Oocysts frequently contaminate feed and water. When other animals ingest the sporulated oocysts, the oocysts start their life cycle again in the new host.

In 3-week-old to 6-week-old suckling calves, clinical signs of coccidiosis may develop following stressful events such as weather changes, or if the calves are in unsanitary conditions. Symptoms or signs of coccidiosis will depend on the stage of the disease at the time of observation.

Coccidiosis affects the intestinal tract and creates symptoms associated with it. In mild cases calves only have a watery diarrhea. But in most cases blood is present in the feces. Straining, rapid dehydration, weight loss and anorexia may be evident.

Animals that survive for 10 to 14 days may recover but permanent damage may occur. The lesions associated with coccidiosis that are found after death generally are confined to the cecum, colon, ileum and rectum.

A diagnosis should be based on laboratory findings and clinical signs. Other infectious diseases such as salmonella and the bovine viral diarrhea virus also may lead to blood in the stool.

Animal susceptibility to coccidiosis varies. Coccidiosis frequently is referred to as an opportunist, which is a disease that will develop when other stress factors are present — or in young calves when exposure to the oocysts is overwhelming. The life cycle of coccidiosis in calves is about 21 days.

That means if a 3-week-old calf is showing signs and symptoms of coccidiosis, the calf was exposed to the oocysts at birth. The logical conclusion to young-calf coccidiosis is that calving grounds are contaminated.

Infected animals must be treated for the infection and to correct dehydration. Producers should select the proper drugs in consultation with veterinarians. Sulfa drugs and a therapeutic dose of amprolium are available to treat coccidiosis. Antibiotics may be necessary if secondary bacterial infections are suspected. Products also are available for treating the entire group of calves, but medicating all calves in beef herds is difficult.

Treatment and prevention are most effective when started early. Move calving grounds to a clean area free of contamination. Increase the amount of space per cow during the calving season. Feed an additive that can reduce the presence of coccidia. Visit for more information.

Dr. Gerald Stokka, veterinarian, is a livestock-stewardship specialist for the North Dakota State University-Extension.