Heligmosomoides polygyrus (Nematoda): the influence of dietary protein on the dynamics of repeated infection.

The influence of the protein component in the diet of the host on the population dynamics of gastrointestinal helminth infection was studied by using a mouse-H. polygyrus experimental model. Mice fed a 2% (by mass) protein diet ad libitum maintained body weight during the experiment, but gained weight steadily when fed a diet containing 8% (by mass) protein. When repeatedly infected with 5, 10, 20 or 40 larvae every 2 weeks, the mice fed the 2% (by mass) protein diet accumulated adult worms in direct proportion to exposure to the infective stages. Under similar infection régimes, mice fed an 8% (by mass) protein diet acquired a partly effective immunity to reinfection by the nematode. Acquired immunity was principally manifest as a reduction in the survival of adult worms, although a slight increase in the mortality rate and/or the development time of the tissue-dwelling larval phase was observed. Worm fecundity per head was significantly depressed in hosts fed the 8% protein diet. In conclusion, in these experiments it is demonstrated that the nutritional status of the host can influence the population dynamics of helminth infection.