RESUMEN
Background: During the twentieth century there was a change in the pattern of diseases in Europe, with an increase in the incidence of allergies and autoimmune disorders, that paralleled a decrease of infectious conditions. The Hygiene hypothesis proposes that these phenomena are causally related. Aim: To evaluate the epidemiological changes of allergic, autoimmune, and infectious diseases in Chile between 1950 and 2003. Material and methods: Search for the incidence and prevalence of these diseases in the national records published by the Ministry of Health, as well as through a systematic search of national literature using PubMed and Scielo as search engines. Results: The annual incidence of tuberculosis, rheumatic fever, measles, and typhoid fever has progressively diminished in Chile since 1970. Figures for the national prevalence for asthma, rheumatoid arthritis, and type I diabetes are scarce and difficult to compare, but clearly show an increasing epidemiological trend in the last 20 years. Conclusions: The national figures suggest that, although the country has only recently gone through an epidemiological transition in health problems, there are detectable changes that show the same trends described in Europe.