The effect of the protein content of CBA/Ca mouse diet on the population dynamics of Trichuris muris (Nematoda) in primary infection.

The relationship between host dietary protein and intestinal helminth population biology during primary infection was studied using a mouse-T. muris experimental model. Uninfected CBA/Ca mice fed either a 4% (by mass) or 16% protein diet grew at a similar rate, but both suffered significant growth retardation when infected with T. muris. T. muris initial establishment and fecundity were unaffected by dietary protein content, but were significantly influenced by infection dose, declining at the higher level of infection. Dietary protein deficiency increased parasite survival at high infection levels. Heavily infected hosts fed the 16% protein diet were found to expel almost the whole of their infections around day 21 p.i. By contrast, this response appeared defective in hosts fed the lower 4% protein diet, resulting in the establishment and survival of large, chronic and patent infections. Mean faecal egg output per mouse increased with infection dose in animals fed a low protein diet, but was low and unrelated to infection exposure in hosts fed the 16% protein diet. It is concluded that low protein levels in diet, via alterations in host resistance, may have an important influence on the transmission of T. muris.