ABSTRACT
High-intensity rearing systems, particularly in the poultry industry, have resulted in a dependence on anticoccidial feed additives to provide prophylactic control against protozoal infections caused by pathogenic species of Eimeria (1). Nine species of coccidia belonging to the genus Eimeria are known to infect poultry that are most susceptible, due to the warm humid environment created in intensive rearing units on modern farms. The degree of pathogenesis caused by each species of Eimeria varies. The most pathogenic species in chickens are Eimeria tenella, Eimeria necatrix, and Eimeria brunetti, which can give rise to spectacular outbreaks of disease. In addition to poultry, coccidiosis also affects pigs, cattle, and sheep. However, the disease is usually less than a problem in food-producing animals other than chickens since pigs, cattle, and sheep are reared less intensively with less chance of infection.
