Coccidiosis is a serious poultry disease that infects the lining of the intestines. The tissue damage caused by coccidia results in lower feed intake, interference with normal digestion and nutrient absorption, dehydration and blood loss. Chickens suffering from coccidiosis quickly become less productive and, if they survive, poor performance continues the rest of their lives.

Three species of coccidia are responsible for the majority of coccidiosis infections: Eimeria acervulina, E. maxima and E. tenella. The severity of a coccidiosis outbreak in a poultry operation depends on a variety of factors including the overall health of the birds before infection, proper nutrition, the presence of other diseases in the flock and the size of the flock. Generally, the larger the flock, the greater the threat of coccidiosis. Young birds are especially susceptible to coccidiosis because they lack passively transferred maternal antibodies to the disease.

Life Cycle and Symptoms

A chicken becomes infected by ingesting infected food or litter. Once ingested, the coccidia quickly invade and replicate in the intestinal lining. The diseased bird spreads coccidia to surrounding birds via feces. A sick bird can show coccidiosis symptoms as soon as 3 days after infection. Birds with coccidiosis may show many of the following symptoms:

• Droopiness
• Listlessness
• Reduced skin pigmentation
• Ruffled feathers
• Unthrifty appearance
• Huddling or looking chilled
• Blood or mucus in the feces
• Diarrhea
• Drop in egg production
• Death loss, especially among young birds

Poultry facility observations and postmortem laboratory examinations all help confirm the presence of coccidiosis in a flock and rule out other diseases with similar symptoms.

Poultry facility observations 
Review the facility’s history. Is there a history of coccidiosis in the operation?
Observe the flock. Do any birds look dull and depressed or have ruffled feathers? Are any reluctant to feed or huddling together
Inspect the litter. Are there areas of dampness or loose feces containing mucus and/or blood?

Postmortem observations 
Examine the intestines of birds postmortem. Intestines from coccidiosis-infected birds are often thicker than normal with light-colored spots on the inside and outside of the intestine. Red pinpoint lesions or streaks are also evidence of coccidiosis.

Laboratory examinations 
Lab tests of multiple fecal samples and intestinal scrapings should be combined with facility and postmortem observations to confirm a coccidiosis diagnosis.

Control

The most effective coccidiosis management programs incorporate a variety of medicinal and animal husbandry strategies. Always consult with a veterinarian or other poultry health professional to develop a coccidiosis management program that’s right for the unique situation.

Animal Husbandry
Litter management. Coccidiosis thrives in environments with high humidity and excessive litter moisture. Replace wet litter right away. Keep roofs and waterers in good repair to prevent leaks. Maintain heat lamps to help reduce moisture levels.

Ventilation control. Proper ventilation helps keep litter dry.

Rations management. Limit protein and salt in rations because high levels of these nutrients cause wetter litter.

Biosecurity. Before entering a poultry facility, employees and visitors must wear plastic or rubber boots and wash footwear using foot pans.

Medicinal Treatment and Prevention
Anticoccidials and live vaccines are the two main medicinal methods used to help control coccidiosis.

Anticoccidials. Anticoccidials are broad-spectrum products administered via feed from day one until approximately one week before marketing to help prevent coccidiosis during the period when birds are most at risk for the disease. Anticoccidials are often not used as the primary control method for coccidiosis.

Live vaccines. Chickens can develop immunity to specific species of coccidia when exposed to small amounts of coccidia. Vaccines containing live coccidia species stimulate an immunological response in vaccinated birds, helping them develop a strong immunity to the disease. Because of this live vaccines are a major component of coccidiosis control programs.

Vaccination Methods 
Vaccines can be administered by edible gel, feed spray, drinking water, eye spray, spray cabinets and, most recently, in ovo. With the exception of in ovo vaccination, current vaccination methods provide no assurance of equal exposure to coccidia across the flock because it is difficult to administer the vaccine uniformly using these methods.

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1. Lillehoj H. Functional genomics approaches to study host pathogen interactions to mucosal pathogens, in Proceedings. Korean Society of Poultry Science Meeting, November 10, 2006; Suwon, Korea.