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Epidemiology of HIV and AIDS
Epidemiology is the study of how disease is distributed in populations and of the factors that influence or determine this distribution. Epidemiologists try to discover why a disease develops in some people and not in others.
Since HIV was first identified in 1983, researchers have worked to pinpoint the origin of the virus. The most commonly accepted theory is that HIV came from a simian (monkey) virus that spread to humans in Africa during the 1930's and 1940's.
The transmission of HIV has been driven by multiple changes in migration, housing, travel, sexual practices, drug use, war, and economics that have affected both Africa and the entire world since 1940.
AIDS was first recognized in the United States in 1981. Since then, the number of AIDS cases has continued to increase both in the U.S. and in other countries. In 1983, the virus that we now know to be HIV was identified as the cause of AIDS.
People who are infected with HIV come from all races, all countries, sexual orientations, genders, and income levels. Globally, most of the people who are infected with HIV have not been tested, and are unaware that they are living with the virus.
Reported AIDS Cases Worldwide
The number of HIV-infected people worldwide has grown dramatically. In 2005 there were 40 million people worldwide living with HIV; of those 40 million, 5 million were newly diagnosed in 2005 (OWH, 2006).
Reported AIDS Cases in the US
At the end of 2003, an estimated 1,039,000 to 1,185,000 persons in the United States were living with HIV/AIDS. In 2003, 32,048 cases of HIV/AIDS were reported from the 33 areas (32 states and the US Virgin Islands) with long-term, confidential name-based HIV reporting. When all 50 states are considered, CDC estimates that approximately 40,000 persons become infected with HIV each year (CDC, 2005a).
The NAMES Project AIDS quilt, representing people who have died of AIDS, in front of the Washington Monument. Courtesy of the National Institutes of Health.
As therapies have improved, fewer people have died of AIDS each year. However, the treatments have not reduced the number of new infections. The Centers for Disease Control and Prevention (CDC) estimates that in the US, there are 40,000 new cases of HIV infections per year. This number has been steady for more than 5 years.
The discovery of antiviral "combination" medication therapies, the antiretrovirals (ART) in 1996 resulted in a dramatic decrease in the number of deaths due to AIDS among persons taking the drug therapies. The unfortunate truth is that many people who have access to the drug therapies may not benefit from them, or may not be able to tolerate the side effects. The medications are expensive and require strict dosing schedules. In developing countries, due to lack of access to healthcare systems and cost, many people with HIV have no access to the newer drug therapies.
HIV and AIDS Cases are Reportable
Reporting of HIV/AIDS will be covered in more detail in the Legal section which appears later in this course. HIV cases reporting requirements vary from state to state.
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AIDS
