ABSTRACT
The immunobiology of avian coccidiosis involves a complex interplay between the various life stages of Eimeria parasites and host intestinal epithelial and immune cells. This chapter reviews various aspects of the host immune response against coccidiosis in different animal species with a primary focus on chicken coccidiosis and identify the major components that are involved in immunity to Eimeria spp. The role of host genetics in influencing susceptibility to coccidiosis demonstrates that non-MHC molecules may have a major influence on disease susceptibility, although chickens with certain MHC types have higher susceptibility to Eimeria infection. Coccidia can infect animals of all ages and usually cause no clinical signs as immunity is quickly acquired and maintained by continuous exposure to reinfection. Along with Eimeria bovis, other coccidian parasites such as Neospora caninum and Toxoplasma gondii have a significant role in immunomodulation in coccidiosis.
