The host-parasite relationships in normal and protein-malnourished cotton rats infected with Litomosoides carinii (Nematoda: Filarioidea).

A total of 120 young cotton rats were fed ad libitum for 10 weeks on either synthetic diets containing 2.5, 5, 10 or 15% casein or on a stock breeding diet containing 20% crude protein. Half of the animals in each group were infected with the filarial nematode Litomosoides carinii and the food intake and body weight of each animal was measured. There was a trend towards increased food consumption in protein-deficient cotton rats and this was increased further in infected animals; however, differences between groups were not significant. Low protein diets reduced the rate of growth of uninfected and infected cotton rats; filarial infection intensified these adverse effects of under-nutrition and increased the number of rats which died in the lowest protein group. Protein deficiency had little effect on the number of L. carinii which developed, although fewer parasites became established in cotton rats fed on a 2.5% diet than in those fed on a 10% diet. Parasites developing in protein-deficient animals were shorter than those developing in well-fed ones and embryogenesis was retarded in female worms from protein-deficient animals. The onset of patency was retarded in protein-deficient animals and the microfilaraemia which developed subsequently was lower up to 120 days post-infection.