Coccidiosis is a protozoal parasitic infection which affects domestic animals and humans, causing diarrhoea. There is a 2-10% mortality rate of cattle from emaciation. Sheep, goats, fowl and rabbits also die from the disease, but death rarely occurs in dogs, cats or man. Coccidiosis particularly affects young animals and animals that are confined in crowded and insanitary conditions. Transmission is basically through infected faeces and the disease is usually contracted by cattle, sheep and goats from pastureland or from contaminated food or water, if they are penned. Overcrowding, bad ventilation, and unsanitary conditions can lead to infection of chickens and other fowl, also dogs and cats. Chickens rarely contract the disease when on free range.
There are two main kinds of coccidia: protozoans of the genera Eimeria and Isospora, both of which contain many species.
Highest incidence of the disease occurs in summer and early autumn, especially in wet or marshland areas.