Practical use of vaccines for the control of coccidiosis in the chicken

Abstract

Immunological control is recognised as the only major practical alternative to chemotherapy for the control of coccidiosis. Initial hopes that it would be possible to develop a genetically engineered vaccine against Eimeria species have not yet been realised, and there is therefore renewed interest in the development and application of vaccines based upon live parasites. Recognition that existing drugs are not as effective as in the past, that few new drugs are currently under investigation, and that the inclusion of drugs in the feed may be restricted in the future has focused attention on the need for new vaccines. Although considerable research has been undertaken on the basic mechanisms involved in the acquisition of immunity, very little attention has been given to the practical aspects of vaccination. In order for an anticoccidial drug to be successful, it is necessary to generate considerable information on efficacy and safety. With few exceptions, little information is available to support the use of coccidiosis vaccines. Hopefully, the introduction of new vaccines and improved application methods will encourage manufacturers to generate more information concerning their products. In future, coccidiosis should be controlled by adopting an integrated approach where drugs and vaccines are both used to prevent this disease. In addition to immunisation, a possible advantage to the application of certain vaccines is that their use could repopulate a poultry house with drug-sensitive organisms. Theoretical rotation programmes, in which the use of drugs is alternated with that of vaccines, are described.