The AIDS Epidemic

In the United States, 1981 - Early 1990s

This scanning electron microscopic image revealed the presence of the human immunodeficiency virus (HIV) which had been co-cultivated with human lymphocytes.

On June 5, 1981, CDC published a report in the Morbidity and Mortality Weekly Report that described a deadly disease affecting a few gay men in Los Angeles. This notice turned out to be the first reported cases of Acquired Immunodeficiency Syndrome (AIDS).

A retrovirus, the Human Immunodeficiency Virus (HIV), was identified in 1983 as the pathogen responsible for Acquired Immunodeficiency Syndrome (AIDS). AIDS is characterized by changes in the population of T-cell lymphocytes that play a key role in the immune defense system. In the infected individual, the virus causes a depletion of T-cells, called "T-helper cells," which leaves these patients susceptible to opportunistic infections, and certain malignancies.

CDC was at the center of defining and understanding this "medical mystery." Faced with a new disease of unknown origins, CDC epidemiologists and other collaborators constructed theories to explain and identify the cause of the disease. They traveled on controversial terrain when the investigation became identified with specific population groups and behaviors. Even with the twists and turns in the early years of the AIDS epidemic, CDC's activities were always based on strong, evidence-based science.