Occurrence: Worldwide.
Species affected: Mostly Chickens, some species can also have disease including turkeys, quail and pheasants.
Age affected: All ages after 7 days of age.
Causes: Protozoan parasites of the genus Eimeria. Nine species occur in the chicken, of which E. tenellaE. maximaE. necatrixE. acervulinaE. dispersa are the most important.
Effects: Watery and/or bloody droppings, poor weight gain and feed conversion, anaemia, depression, drop in egg production in layers. Morbidity can be as high as 100%, mortality ranges from 0-50%.