Nutrition-parasite interaction

The interactions between host nutrition and parasitism in ruminants are vie wed within a framework that accounts for the allocation of scarce nutrient resources, such as energy and protein, between the various competing body f unctions of the host. These include functions that are the direct result of parasitism. Since it is proposed that the host gives priority to the rever sal of the pathophysiological consequences of parasitism over other body fu nctions, it is to be expected that improved nutrition will always lead to i mproved resilience. On the other hand, it is proposed that the function of growth, pregnancy and lactation are prioritised over the expression of immu nity. Thus, improved nutrition may affect the degree of expression of immun ity during these phases. The framework is useful at highlighting areas of f uture research on host/parasite/nutrition interactions. Its suggestions can account for the observations of the periparturient relaxation of immunity in reproducing females, as well as the reduction in worm burden in small ru minants supplemented with additional protein. Although developed for gastro intestinal nematodes in ruminants, the concepts of the framework should be applicable to the interactions of nutrition in other parasitic diseases. (C ) 1999 Elsevier Science B.V. All rights reserved.