Gordon memorial lecture. Coccidiosis control: past, present and future

Hygiene, management, chemotherapy and immunity all play a part in the control of coccidiosis. Under the conditions of modern intensive poultry rearing, special reliance is placed upon chemotherapy and since the introduction of the sulphonamides in 1939 a sequence of different types of drugs has been developed. At present the field is dominated by the ionophore antibiotics which have a special mode of action against the extracellular phases of the parasitic life cycle. Drug resistance is a continuing problem which has limited the effective life of most types of drug, although it has been most significant for particular compounds. So far it has not severely affected the efficacy of the ionophores. Immunity is involved in effective prophylaxis and the strong protective immunity which is a feature of most coccidial infections offers promise of a vaccination system. However, much more research will be necessary to bring this promise to fruition. Studies on immune mechanisms, antigenicity, biochemistry and in vitro cultivation may all contribute to the development of methods for controlling a series of infections which are an important obstacle to the development of modern husbandry methods.