Infectivity, fecundity, and survival of Nematospiroides dubius in gnotobiotic mice

Nematospiroides dubius infections were produced and studied in germfree, gnotobiotic (monoassociated with a Lactobacillus), and conventional mice in three experiments. These mice were infected with axenic N. dubius larvae and were sacrificed at 2, 4, and 6 weeks after exposure. Observations made included numbers of adult N. dubius and parasitic nodules in the small intestine, and numbers of eggs in uteri in selected female N. dubius and in fecal material. Significantly ( P < 0.05) more N. dubius were found in conventional than in germfree or gnotobiotic mice examined 4 and 6 weeks after exposure. Gnotobiotic mice tended to have more N. dubius than germfree mice by 6 weeks after exposure but these differences were not statistically significant in all comparisons. Increasing the time period between monoassociation with Lactobacillus and exposure to N. dubius appeared to favor the development and survival of the parasite. More parasitic nodules were observed in germfree than in conventional hosts in all comparisons. Numbers of nodules in gnotobiotic mice tended to be greater than in conventional, but less than in germfree hosts. Egg production of N. dubius was greater in conventional than germfree mice, while that in gnotobiotic mice occupied an intermediate position.