Immunological control of coccidiosis in poultry

Coccidiosis – caused by parasites of the genus Eimeria – is an infection known to damage poultry. Eimeria spp. follow a typical coccidian lifestyle consisting of an endogenous asexual and sexual phase and an exogenous infectious phase. Eimeria spp. infections are self-limiting because the number of asexual, pathogenic, cycles is genetically pre-determined. However, the infection may be chronic because of oocyst cycling in feces. Coccidiosis is a burden on the poultry industry and many preventive anticoccidial drugs have been created; however, a major limit is emerging drug resistance. Live vaccination is another method of coccidiosis prevention where protective immunity is developed by a dose of non-attenuated Eimeria spp. that is then cycled in the feces to produce protective immunity. The cycling of the controlled infection with live vaccination of replacement laying hens is influenced by commercial caging techniques. This review provides an overview of coccidiosis caused by Eimeria species infecting domestic fowl and the nature of coccidial infections in commercial poultry houses