[Epidemiology of HIV infection: twenty-years of experience].

In the 20 years since the isolation of HIV, an overwhelming amount of information about this entity has come up and transform this disease into a chronic and manageable one. In spite of all this knowledge, failure to prevent new infections is still common in many parts of the world, especially those acquired by sexual and intravenous drug use. Sub-Saharan Africa is still the most affected region of the world, where the meridional region presents the largest incidence of all (30%) and contains only 2% of the world population.