Introduction

This condition of chickens, seen worldwide, is caused by the protozoan parasite Eimeria mitis, which colonises the small intestine.

The infective agent is found in litter, faeces and on fomites and birds are infected by the oral route with an incubation period of 2-5 days. The disease occurring is proportional to the amount of infective agent ingested.

The parasite is moderately resistant in the environment and highly resistant to conventional disinfectants.

Predisposing factors include exposure to faeces and litter conditions that favour development of the parasite (temperature, humidity).

Signs

• Reduced feed conversion efficiency and weight gain. May predispose to wet litter, secondary bacterial enteritis.

Post-mortem lesions

• The lesions are minimal and located in the lower small intestine (ileum) which tends to be pale and flaccid with scattered petechiae.

Diagnosis

Mild lesions, identification of typical small round oocysts and other stages in fresh scrapings from the small intestine.

Treatment

Not usually treated but susceptible to the products used for other forms of intestinal coccidiosis.

Prevention

Normally controlled by anticoccidials in feed. May be included in vaccines.