Coccidiosis in Chickens
Coccidiosis is one of the most common and costly diseases seen in chickens, particularly in birds raised on the ground—such as free-range or those kept on litter floors. It’s caused by a microscopic parasite that attacks the gut, leading to poor health, slower growth, and sometimes death if left untreated.
What Causes Coccidiosis
Coccidiosis is caused by several species of Eimeria, a group of tiny, single-celled parasites (called coccidia). These parasites live inside the lining of the gut, damaging it as they multiply. This damage reduces the chicken’s ability to absorb nutrients and can cause dehydration, blood loss, and make birds more vulnerable to other gut infections.
Each bird species has its own type of coccidia—so the ones that affect chickens don’t spread to ducks, turkeys, or other birds.
There are three key species of Eimeria that affect chickens, E. acervulina, E. maxima, and E. tenella. Some cause disease in the intestines, while one species targets the caeca (the pouch at the junction of the small and large intestine). Chickens can be infected by more than one species at the same time.
How It Spreads
Coccidiosis spreads through droppings. Infected birds pass tiny, egg-like structures called oocysts in their manure. When the environment is warm and damp, these oocysts become infective and can survive in litter, soil, and on equipment. Chickens become infected when they pick up and swallow these oocysts while scratching or pecking around. Once inside the gut, the parasites multiply rapidly, completing their life cycle in just 2 to 5 days, so infections can spread very quickly through a flock.
Which Birds Are at Risk
All poultry can get coccidiosis, but it’s most common in young chickens between 3 and 20 weeks of age. Very young chicks are usually protected for the first few weeks until the parasite builds up in the environment.
Signs to Watch For
Signs of coccidiosis can vary depending on how severe the infection is and which part of the gut is affected. Common signs include:
• Dullness or depression
• Pale combs
• Reduced appetite or weight loss
• Ruffled feathers
• Droppings with excess water, mucus or blood (blood is more common with caecal coccidiosis)
• Dirty feathers around the vent (more common with intestinal coccidiosis)
How It Affects Your Flock
Even mild coccidiosis can cause big production losses:
• Slower growth and poor feed conversion in meat birds
• Drop in egg production or poor eggshell quality in layers
• Greater risk of secondary gut infections including enteritis
Birds gradually build immunity to the coccidia they’re exposed to, but a heavy infection or exposure to unfamiliar species can still cause disease. Immunity to one species doesn’t protect against others.
Prevention and Control
1. Good Hygiene
• Keep litter as dry as possible—coccidia thrive in damp conditions.
• Manage drinkers to prevent leaks and wet spots.
• Maintain good ventilation and turn the litter if needed.
• Practise biosecurity: clean boots, control rodents, and keep wild birds away from feed and housing.
2. Medication
Coccidiostats (anti-coccidial medications) can be added to feed or water to help prevent or control outbreaks of coccidiosis.
For active infections, several treatment options are available. The most commonly used medications are amprolium and toltrazuril, both of which are effective against the coccidia species that affect chickens.
If you suspect coccidiosis in your flock, contact your veterinarian as soon as possible. Early diagnosis and prompt treatment are essential to reduce losses and prevent the disease from spreading.
Key Takeaway
Coccidiosis can spread quickly—but with good hygiene, sound management, and the right vaccination or medication program, it can be effectively controlled. Keeping litter dry, practising good biosecurity, and monitoring your flock daily are the best ways to protect your chickens.
More Information
For more information on Abbey’s coccidiosis medications and how they can help prevent and treat disease in your flock, please follow the links below:
https://abbeylabs.com.au/product/coxi-quell-25-coccidiocide-solution-for-poultry/
https://abbeylabs.com.au/product/coxi-stat-coccidiocide-solution-for-poultry/