Onset of resistance to light Hymenolepis nana infection in mice of different strains.

Rapidity in onset of resistance against Hymenolepis nana egg infection after a light primary infection was studied in low and high responder mice challenged at different time intervals. A very rapid acquisition of protection was observed in C57 and a delayed response in C3H mice. In both cases the effect of resistance on weight or worm number was related to the time of challenge infection, suggesting a "race against time" involving host response and parasite development, the outcome varying according to host genetic background.