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COCCIDIOSIS, CAECAL, E tenella

Introduction

This was at one time the commonest type of coccidiosis and is certainly the most easily diagnosed. It is caused by Eimeria tenella and results in lesions in the caecum of chickens worldwide. Morbidity is 10-40% and mortality up to 50%. Transmission as for E. mitis (see above).

Signs

• Depression.

• Ruffled feathers.

• Closed eyes.

• Inappetance.

• Diarrhoea, blood in faeces.

• Production less affected than in some of the other forms of coccidiosis.

Post-mortem lesions

• Petechiae.

• Thickening, ecchymoses, of caecal mucosa.

• Accumulation of varying quantities of blood and caseous necrotic material in the caecum.

Diagnosis

Signs, lesions, microscopic examination of scrapings. Differentiate from ulcerative enteritis, histomonosis.

Treatment

Toltrazuril, Sulphonamides, Amprolium, Vitamins A and K in feed or water.

Prevention

Coccidiostats in feed, vaccination by controlled exposure, hygiene. E. tenella is more common when 'straight' ionophore programmes are used. Shuttle programmes with chemicals in the starter diet usually improve control. In some markets the organic arsenical compound 3-Nitro is used as an aid in the control of caecal coccidiosis. Vaccines are used mainly in breeders but increasingly in broilers. Recovered birds have good immunity to the same parasite

COCCIDIOSIS,  E mitis

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.