Sex differences in parasitic infections: Beyond the dogma of female-biased resistance

Abstract

Sex differences in parasitic infections are a biological phenomenon of considerable significance for individual health and disease as well as for the evolution of a species. The general rule of thumb is that females are more resistant to infectious diseases than males. There are, however, many notable exceptions to this rule that illustrate a female bias in susceptibility to infection. By studying sex differences to cysticercosis infection, it has been demonstrated that females are more likely than males to become infected, to carry larger parasite loads, to be more severely affected, and more reticent to developing protective immunity. Our animal studies illustrate that female-biased susceptibility to parasitic infection is influenced by hormones, reproductive status, age, and genetic background. The mechanisms underlying the sexual dimorphism in murine cysticercosis involve the effects of sex steroids on both the host immune and central nervous systems as well as directly on the parasite. In this chapter, the causes of female-biased susceptibility to parasitic, and possibly other, infections are examined.