The effects of host sex and hormones on Trichinella spiralis in the mouse.

The effects of host's sex and hormones on the number of adult Trichinella spiralis in the small intestine, the number of migratory larvae produced in vitro by adult female worms, and the number of muscle larvae per gram of body weight were examined in CD-1 Swiss white mice. Nongonadectomized (intact) male mice housed greater numbers of adult worms and a greater number of muscle larvae per gram of body weight than did intact female mice. Adult female worms isolated from intact male mice deposited greater numbers of migratory larvae in vitro than did those obtained from intact female mice. These differences between intact male and intact female mice were eliminated by gonadectomy of male and female mice. Injection of increasing amounts of heterologous sex hormone into intact male and female mice was accompanied by decreasing rates of in vitro larvaposition by adult worms from male mice; but adult worms isolated from female mice showed increasing rates of in vitro larvaposition. Injection of heterologous sex hormone into gonadectomized male and female mice caused a reversal of the findings for intact, uninjected male and female mice stated above. This study has demonstrated that host sex and host sex hormones affect the biology of T. spiralis in the CD-1 Swiss white mouse.