http://fieldcasestudy.com Coccidia is a microscopic parasitic organism that infects poultry when ingested by the chicken. The parasites found in the ground or bird faeces attaches itself to the lining in the gut, multiplies and becomes an oocyst feeding in the digestive tract which will make it bleed. Once infected it passes the parasites in its poop days before symptoms occur. Coccidiosis is caused by protozoa of the phylum Apicomplexa, family Eimeriidae. In poultry, most species belong to the genus Eimeria and infect various sites in the intestine.