Coccidia In Birds & Poultry

Coccidia (Eimeria spp) can infect most domestic poultry and game birds, including turkeys, chickens, partridges, peacocks, pheasants and quail. There are six species of Eimeria (coccidiosis) considered significant for chickens: E. tenella, E. brunetti, E. necatrix, E. maxima, E. mitis and E. acervulina, each of which are particular to a specific region of the gut. For the purposes of treatment and prevention it’s unimportant to identify species as treatment is the same.

The number of coccidial oocysts relates to burden of infection, relatively high levels may be seen without disease present. Monitor levels, look out for symptoms and consult your vet where necessary.

Cocciidial oocysts in a poultry sample under the microscope:

Cocci hen worm egg count


The poultry keeper’s aim is to expose birds to low levels of coccidiosis to enable them to build up natural immunity but not so many that they succumb to disease. It's important to be especially careful with ex battery and caged hens which, if suddenly exposed to coccidiosis, can succumb to disease.


A protozoan parasite that invades and destroys cells in the gut wall causing pain and loss of appetite. Gut damage then reduces ability to absorb nutrients resulting in weight loss and diarrhoea. In severe cases this causes blood in the droppings and anaemia characterised by a pale comb and wattles.

Gut damage can also disrupt the natural balance of bacteria in the digestive tract thereby allowing harmful bacteria to take over and cross the damaged gut wall causing blood poisoning.

Affected birds often adopt a hunched posture with ruffled feathers.

Droppings in birds with cocci often present with symptoms of gut damage:

Dropping of bird with cocci


Although medication is available over the counter to treat pigeons for cocci, it's use in poultry can only be prescribed by a vet using the cascade system. This is to prevent strong chemicals getting into the food chain. Once treated there is no known safe withdrawal and therefore it is recommended never to eat eggs or meat of treated birds.

This means most vets are reluctant to prescribe until the burden is considerable and clinical disease is also present; usually + 50,000 e.p.g. on a worm egg count test.