Protozoan Infections of Domestic Animals: Coccidian and Related Infections

Abstract

Among parasitic diseases of domestic animals, few have the widespread importance ascribed to the coccidia. Historically, poultry were most vulnerable to coccidiosis, because large numbers of birds were reared in confinement. Most domestic animals are susceptible to coccidiosis; wherever young animals are gathered together in close quarters, such as in lambing or calving sheds or around watering or feeding facilities, there is likely to be some prevalence of coccidiosis. Most of the economic damage can be done to chickens by this disease before the clinical signs are recognized, making prevention more important than treatment of sick animals. Thus, the practice of giving medication in the feed as a prophylactic measure is well accepted in the poultry industry. The cost of prophylactic medication has been estimated at more than $280 million worldwide. Despite this expenditure, losses to coccidiosis in poultry continue; drugs are not completely effective, drug resistance sometimes becomes a problem, and the drug may be inadvertently omitted because of erroneous feed-mill operation. More new drugs and alternative control measures are always needed to maintain good control of this important disease.