Resistance of mice to secondary infection with Schistosoma mansoni. I. Comparison of bisexual and unisexual initial infections.

Mice receiving a unisexual primary infection with either sex of Schistosoma mansoni did not develop detectable resistance to reinfection. In contrast, mice receiving a bisexual primary infection developed a high degree of resistance. The number of adult worms developing from the challenge infection was reduced, relative to controls, by 72--100% at challenge times of 6 weeks or greater.