Coccidiosis can be a serious disease of young cattle. It is caused by a number of species of the one-celled protozoa, Eimeria.

The Life Cycle

Oocysts from infected animals are passed out with the faeces. With the right environmental conditions (moisture and temperature) the oocytes sporulate (hatch and divide) and are ingested from contaminated facilities or pasture. They invade the cells of the lining of the small intestine where they grow and multiply. The intestinal cells hosting these parasites rupture causing damage to the intestinal lining. The parasite then invades the large intestine cells where they reproduce causing damage, eventually forming oocytes which are passed in the faeces.

Signs and symptoms

Coccidiosis usually occurs in calves between 3 and 8 months of age, but can occur as young as 4 weeks. Most cattle are infected with low numbers of Eimeria but clinical disease results if they are subject to heavy infestations or if the animal’s resistance is lowered by stress, poor nutrition, or other disease.

Clinical signs range from mild to severe and include diarrhoea with a distinctive circular pattern of faeces around the tail. It is often blood-stained with mucus. The calves strain and swish their tails. Appetite can be diminished. Death is predominantly a result of electrolyte loss and dehydration caused by the diarrhoea.

The Impact

The effect of the disease on the performance of dairy replacement heifer and dairy beef is recognized. It can be a major problem on individual dairy properties and with weaned heifers on dairy grazing properties. The disease is characterized by high morbidity (infection levels), with moderate deaths and impaired performance of calves that recover.

Because the oocytes are present in the soil and in calf sheds on infected properties, infection carries over to the next season, so farmers are warned to look for early signs of Coccidiosis and start treatment early before an outbreak becomes serious. Economic losses result from poor growth rates, occasional deaths and treatment costs.

Management and Control

To achieve effective control of Coccidiosis good management and hygiene is vital. These include:

  • reducing stock density
  • regularly shifting feed and water troughs
  • preventing faecal contamination of feed and water troughs
  • increasing bedding to reduce faecal contamination, and
  • cleaning and disinfecting buildings with steam or water blasting and spraying with a product that kills Oocysts.

Prevention can be achieved by feeding meal containing coccidiostats. The danger is that when meal feeding is ceased too early after weaning symptoms of Coccidiosis may occur.


Infected calves should be separated from the rest. Treatment is by using toltrazuril (Baycox) which is a coccidiocide (kills coccidia). All of the mob including those without symptoms would usually be treated.