ABSTRACT
The relationship between a parasitic organism and its host’s immune system is an extremely complex one. It represents but one aspect of the parasite’s overall interaction with its host, and this like any other ecological relationship has many different facets all of which collectively constitute the characteristics of the parasite’s niche (Kennedy, 1976). As experimental techniques have improved so our knowledge of the host response and the effector mechanisms which it unleashes has expanded, and this has been partially matched by an increasing awareness of the strategies used by parasites to evade host immunity. The conflict between a parasite and its host’s immune system is in some respects a unique aspect of ecology; free-living animals do not contend with a concerted strategy by the environment to terminate their existence in a manner which is quite comparable with the highly specific mammalian response to micro-and macroorganisms (Wakelin, 1976).
