Nippostrongylus (Nematoda) in protein-malnourished rats: host mortality, morbidity and rehabilitation.

The synergistic relationship between host nutrition and the effects of Nippostrongylus was investigated experimentally in rats fed a diet containing 1% (w/w) protein. Rats were infected with 10 doses of N. brasiliensis varying from 0.35 to 99 larvae/g and their daily food intake and weekly body mass were compared with those uninfected rats fed the same diet for a period of 9 weeks. The deterioration of the uninfected rats observed as a result of protein-energy malnutrition was found to be accelerated in a dose-dependent manner in the rats infected with N. brasiliensis. Analysis of food intake and body mass measurements demonstrated that this acceleration was related to a decrease in food intake and indicated a likely alteration in nutrient utilization, both of which were established by the end of the first week of the infection. Remission from the combined effects of malnutrition and infection was achieved by offering the rats a high-protein diet (20% w/w), whereupon rehabilitation was found to be complete within a period of 9 days. The implications of the results and the possible mechanisms involved in their generation are discussed in relation to the frequent coexistence of helminthiasis and malnutrition.