Coccidiosis in Chickens

Coccidiosis is a common intestinal disease in chickens. It can cause severe health problems and even death if left untreated.

Chickens can contract a variety of parasitic protozoa, called coccidia. Each species invades a distinct region of the intestine. It’s also possible that more than one species will infect a chicken at the same time.


A coccidia infection causes an intestinal condition that prevents nutrients from being absorbed.

The main signs of coccidiosis are:

  • Loss of appetite/weight loss
  • Drinking less/dehydration
  • Watery or discolored poop
  • Bloody diarrhea (in serious cases)
  • It causes young chickens to stop growing at a regular rate.
  • Ruffled feathers
  • Hunched up
  • Lethargy
  • Decreased egg production
  • May cause death

The illness could potentially progress slowly or suddenly result in bloody diarrhea and death.

Although they may live, birds are not likely to thrive.


Typically, coccidiosis occurs in wet, filthy, overcrowded facilities.

Additionally, growing chicks 3 to 6 weeks of age are most susceptible, with 4 to 5-week-olds seeing the worst cases.


Chickens can develop immunity in 2 ways:

  1. By progressively being exposed
  2. By surviving the disease

Floor-raised chickens, that are raised in an appropriately clean environment, will develop immunity through progressive exposure as they get older.

Chicks raised on wire and then transferred to floor housing have received limited exposure. As a result, they lack immunity and are susceptible to serious infections.

Also, coccidia develops quickly in hot, humid circumstances, so even adult chickens might catch an infection in such an environment.

However, chickens only develop immunity to the species present in their environment. Healthy chickens from different places may not all be immune to the same species, making them vulnerable to spreading coccidiosis to one another.


Billion of coccidia eggs are shed by sick chickens that seem healthy, and these eggs easily infect young chicks.

Fortunately, the coccidia species that harm chickens do not affect other livestock, and chickens cannot contract any of the several coccidia species that infect other animals (including other poultry species).


Anticoccidial vaccines and probiotics that promote competitive exclusion can both help prevent this dangerous condition.

A coccidiostat or coccidiocide may be used to treat or control it.


One of the many medications used to prevent the development of coccidiosis in chicks is a coccidiostat. A coccidiostat, however, cannot treat chicks who have already contracted the disease.

The coccidiostat is typically included in chick starter (medicated feed).

Medicated vs Unmedicated Feed

If your chicks have been given the coccidiosis vaccine, do not feed them medicated starter feed (Amazon). The amprolium in the medicated feed, which helps protect chicks against coccidiosis, will make the coccidiosis vaccine ineffective.

Give them unmedicated chick starter (Amazon) instead.


One of the many medications used to treat coccidiosis by eradicating coccidia during their development is a coccidiocide.

Since sick chickens may stop eating but may still drink, coccidiocide is typically put in drinking water.

Proper Treatment:

Not all coccidiocides are effective against all varieties of coccidia, and administering the incorrect medication can have a negative impact.

Take a sample of your chicken(s) poop to a veterinarian at the first sign of coccidiosis and request a fecal test to determine the type of coccidia and the appropriate treatment. (Early diagnosis and proper treatment are fast and effective.)

If you would rather not use medications on chicks, you must:

  • Ensure rigorous sanitation of the brooder.
  • Move the chicks into a pasture rotation as soon as you can, no later than 3 or 4 weeks of age.
  • Make sure their drinking water is always kept clean.