Coccidiosis is caused by a host specific species of Eimeria and it is a protozoon common in chickens and less often in turkeys it also occurs occasionally in geese, guineas, pigeons, pheasants, quail, and many other birds. It is usually seen in young birds under conditions of warmth and high humidity or conditions that lead to wet litter.
The infective oocysts are present in the litter having been deposited there by infected chickens. Oocysts are easily transported by blowing dust, boots, clothing, crates, vehicle wheels, other animals, and people.
Susceptible chickens ingest sporulated oocysts in feed, water, litter and become infected. If exposure is moderate, the chickens become immune to that species of coccidia. Outbreaks occur when susceptible chickens ingest massive numbers of oocysts.
Coccidia produce lesions by destruction of epithelial cells in which they develop and multiply and by trauma to the intestinal mucosa and submucosa.
The clinical signs vary with species of coccidia. Pathogenic species cause diarrhoea which may be mucoid or bloody, dehydration, ruffled feathers, anaemia, listlessness, weakness, retraction of the head and neck. In turkeys, the signs are the same except the diarrhoea isn’t bloody.
The prevention of Coccidiosis is usually by the incorporation of anticoccidials in the feed. A low level exposure allows immunity to develop. Various products are available for treatment.