Diseases: Coccidiosis

Introduction

• Caused by protozoan parasites that develop within cells in various parts of the intestine of chickens
• At least nine coccidian (species of the genus Eimeria) infect chickens
• Eimeria tenella (caecal coccidiosis) and Eimeria necatrix (intestinal coccidiosis) are the most important

Clinical Signs

• All ages and breeds are susceptible but young chicks are most susceptible
• Weight loss, depression
• Pale, ruffled feathers
• Blood in the faeces
• High mortality is recorded in some outbreaks

Post Mortem Lesions

• Post mortem changes occur rapidly in the intestine, therefore examine recently dead birds
• Ballooning of intestine or caeca
• Blood and cell debris in the intestine or caeca

Diagnosis

• Clinical signs and post mortem lesions are usually diagnostic
• Various stages of the life cycle can be recognised in smears

Samples

• Smears from intestinal lesions taken onto a glass microscope slide

Transmission

• Oocysts are shed in the faeces and are eaten; the wall of the oocyst is crushed in the gizzard and infectious forms are released
• Oocysts are very resistant

Treatment

• Anticoccidial drugs have been developed for treatment and prevention - availability will vary from country to country.
• Usually given in drinking water
• Drug resistance is a problem
• Withholding periods vary from 0 to 28 days

Prevention and Control

• Commercial poultry producers include coccidiostats in food or water
• Good management and husbandry essential
• Keep litter and floor of poultry house dry
• Adults should be housed in raised houses with slatted floors made of smooth poles or wire netting