Genetic variation in resistance to parasitic infection: experimental approaches and practical applications.

Parasitic infections remain a major threat to the successful maintenance of domestic livestock. Control is still centered around management and husbandry, and the use of chemotherapeutic compounds. However, the spread of drug resistance in many important protozoal and helminth infections is placing an increasing emphasis on the development of alternative forms of control. At the present time vaccination is available for only a limited number of parasites, and may never be practical or cost-effective for some of the most important infections. This review examines current views of the mechanisms, control and likely value of genetically determined differences in resistance to parasitic infection. There is an extensive literature dealing with experimental analyses of genetic variation to parasitic infection in both laboratory and domestic species, and a growing interest in the application of this information in the field of practical parasite control.