Submitted to: Proceedings of the Maryland Nutrition Conference
Publication Type: Proceedings
Publication Acceptance Date: June 12, 1999
Publication Date: N/A
Interpretive Summary: Parasites which infect the intestine cause significant economic losses to the poultry industry since the infection can cause malabsorption of the nutrients and also poor feed utilization. ARS scientists have been studying coccidiosis,a disease caused by the protozoan parasite called coccidia, to develop a new control strategy against this parasite. Coccidiosis costs the industry more than $600 million annually in prophylactic treatment. Drugs have been used to prevent coccidiosis. However, with the increasing concerns over the development of drug-resistant coccidia parasites in the field, a new control strategy is critically needed. In this presentation, recent developments and novel concepts for controlling coccidiosis, based upon immunity, dietary manipulation and genetics will be discussed. The authors review the current understanding of how various nutrients improve the host disease resistance against coccidiosis. They also summarize the new knowledge on the host response to coccidia. The information which is presented in this paper will enhance the feasibility of developing a new control strategy for intestinal parasitism. It will help reduce the major stress factor that can lead to a lowered performance and a lowered production efficiency in livestock and poultry.
Technical Abstract: Intestinal parasitism is a major stress factor that can lead to malnutrition and lowered performance and production efficiency of livestock and poultry. Coccidiosis, an intestinal infection caused by intracellular protozoan parasites belonging to several different species of Eimeria, costs the poultry industry more than $600 million in annual losses. Infection with coccidia parasites seriously impairs the growth and feed utilization of livestock and poultry. However, due to the complex life cycle and intricate host immune responses to Eimeria, coccidia vaccine development has been difficult. Better understanding of the basic immunobiology of pertinent host-parasite interactions is necessary for the development of immunological control strategies against coccidiosis. Although chickens infected with Eimeria spp. produce antibodies in both the circulation and mucosal secretions, humoral immunity plays only a minor role in protection against this disease. Rather, recent evidence implicates cell mediated immunity as the major factor conferring resistance to coccidiosis. This presentation will summarize our current understanding of the avian intestinal immune system and its response to Eimeria as well as provide a conceptual overview of the complex molecular and cellular events involved in intestinal immune responses to enteric pathogens. It is with anticipated optimism that increased basic knowledge on the interaction of parasites and host immunity will stimulate the birth of novel immunological and immunonutritional concepts in intestinal parasitism.