Control of coccidiosis in chickens by vaccination.

Control of coccidiosis in chickens has relied upon managerial measurements and the prophylactic use of coccidiostatic drugs. With the emergence of Eimeria strains that are resistant to these drugs the use and number of commercially available vaccines has increased. In this review various aspects that contribute to the development of coccidiosis are discussed, and an overview of the currently marketed coccidiosis vaccines is presented. Three groups of vaccines can be distinguished based on the characteristics of the Eimeria species included in the products: vaccines based on live virulent strains, vaccines based on live attenuated strains, and vaccines based on live strains that are relatively tolerant to the use of ionophores. These latter vaccines combine the early protective effect of ionophore treatment with the late protective effect of vaccination. The impact of future developments such as recombinant-DNA vaccines and changes in consumer's attitude towards broiler production are discussed.