General life cycle of coccidia

Coccidiosis is a disease caused by a parasitic protozoa (a single celled organism), which damages the intestines—this can result in poor performance and mortality.

Coccidiosis generally effects younger birds and costs the poultry industry millions of pounds every year, in loss of production and treatment. Coccidiosis affects many animals, including ducks, geese, turkeys and pheasants, but each species has its’ own specific infective genus. In chickens there are seven species of the genus Emeria, some can cause more damage than others. Each type manifests in specific areas of the intestine, which aids diagnosis. The coccidia life cycle is complicated and the egg stage is referred to as oocysts. It is possible to carry out oocyst counts on faeces to determine the level of infection. Unlike bacteria the coccidia go through a complicated life cycle and there is a sexual stage leading to the production of oocysts which are then infective to other birds.


Depending on the severity, birds can become withdrawn and display a characteristic posture as shown; ruffled feathers, head sunk and dropped wings, occurring usually between 3-6 weeks of age. Less severe outbreaks may display few signs. Generally combinations of the following are common:

  • Droppings containing signs of blood, orange/red mucous or diarrhoea.
  • Ruffled, hunched posture.
  • Weight loss, loss of appetite and interest in water.
  • Anaemia, shown by pale sunken face or wattles.
  • Slow and possible uneven growth.
  • Weak, listless birds.
  • Huddling and discontentment.

Coccidia have two main phases in their life cycle—one phase outside the host (the chicken) and involves the development of the infective oocyst and the second phase occurs within the host and involves rapid multiplication and sexual reproduction within the gut lining; this is where the damage occurs causing the bird much discomfort.


Coccidiosis is spread by litter/droppings from effective birds, used equipment, humans, wild birds/animals and poor hygiene. It thrives in warm, damp conditions.


Post mortem is the most effective way as the specific type of coccidiosis can often be identified. Faecal tests are also possible by examination under a microscope. The two particular areas where oocysts congregate are the small intestine and the caeca. Coccidiosis has an incubation period of 4-6 days, depending on the species.


Coccidiosis needs to be treated as soon as possible because where there are heavy infections there will be a high mortality relatively quickly. Veterinary treatments are effective in the short term but good management practices are essential. Always contact your vet or one of our poultry consultants if you require further help or information.

Article Taken from The Chicken Vet

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