Echinococcus granulosus in albino mice: Effect of host sex and sex hormones on the growth of hydatid cysts

Abstract

Male and female albino mice were inoculated peritoneally with live scolices of Echinococcus granulosus. A group from each sex was then treated weekly with the homologous sex hormone while another group, also from each sex, received the heterologous hormone. The rest of the animals served as controls. After 21 weeks, the mice were killed and the number and size of cysts found in their abdomens and chests were determined. It was evident that female mice harbored fewer and smaller cysts than the males. This was indicative that male hosts were more susceptible to infection with hydatid. Moreover, the course of the infection was modified by treatment with exogenous hormones. In fact, testosterone seemed to increase the susceptibility of animals of both sexes while estradiol tended to decrease susceptibility. The magnitude of these differences showed a statistically significant inhibition of infection in female mice and thus may account for the variable extent of infection in the groups of mice of mixed sexes. The relationship of gonadal hormones to host resistance in hydatidosis as well as to other helminthic infection, at large, is discussed.