The Effect of Infections on Susceptibility to Autoimmune and Allergic Diseases

The hygiene hypothesis postulates that an environment with a high incidence of infectious diseases protects against allergic and autoimmune diseases, whereas hygienic surroundings increase the incidence of these disorders. This review examines the evidence in support of the hygiene hypothesis and offers a number of mechanisms that could explain the relation between sanitary conditions and susceptibility to allergic and autoimmune diseases.