A report appeared in the CDC’s “Morbidity and Mortality Weekly Report” (MMWR) on June 5, 1981, describing a previously unknown deadly disease in five young homosexual males, all in Los Angeles. The disease was characterized by dramatically reduced immunity, allowing otherwise innocuous organisms to become “opportunistic infections,” rapidly producing fatal infections or cancer. Thus, acquired immune deficiency syndrome (AIDS) first became known to the public health and medical communities. It was soon traced to rectal intercourse, blood transfusions, and reuse of injection needles as methods of transmission. Reuse of needles was a common practice in poor nations. It was also widespread among intravenous drug abusers. Within several years, the disease was traced to a previously unknown retrovirus, which came to be called the human immunodeficiency virus (HIV).
A test was developed to detect the disease and was first used in testing blood for transfusion. Within a short period of time, the blood supply was protected by testing all donated blood, and transmission of HIV by blood transfusion became a rare event. Diagnostic tests for HIV/AIDS soon became available for testing individuals. For many years, these were used by clinicians only for high-risk individuals. In recent years, HIV testing has become more widely used, as the testing no longer requires blood drawing and the results are rapidly available. The CDC has put increasing emphasis on testing as part of routine health care.
In subsequent years, much has been learned about HIV/AIDS. Today, it is primarily a heterosexually transmitted disease with greater risk of transmission from male to females than females to males. In the United States, African Americans are at the greatest risk. Condoms have been demonstrated to reduce the risk of transmission. Abstinence and monogamous sexual relationships likewise eliminate or greatly reduce the risk. Even serial monogamy reduces the risk compared to multiple simultaneous partners. Male circumcision has been shown to reduce the potential to acquire HIV infection by approximately 50%.
In major U.S. cities, the frequency of HIV is often greater than 1% of the population, fulfilling the CDC definition of “high risk.” In these geographic areas, the risk of unprotected intercourse is substantially greater than in most suburban or rural areas. Nearly everyone is susceptible to HIV infection, despite the fact that a small number of people have well documented protection on a genetic basis.
Maternal-to-child transmission is quite frequent and has been shown to be largely preventable by treatments during pregnancy and at the time of delivery. CDC recommendations for universal testing of pregnant women and intervention for all HIV-positive patients have been widely implemented by clinicians and hospitals and have resulted in greatly reduced frequency of maternal-to-child transmissions in the developed countries and in developing countries in recent years.
Medication is now available that greatly reduces the load of HIV present in the blood. These medications delay the progression of HIV and also reduce the ease of spread of the disease. These treatments were rapidly applied to HIV/AIDS patients in developed countries, but it required about a decade before they were widely used in most developing countries. Inadequate funding from developed countries and controversies over patent protection for HIV/AIDS drugs delayed widespread use of these treatments in developing countries.
New and emerging approaches to HIV prevention include use of antiviral medications during breastfeeding, postcoital treatments, and rapid diagnosis and follow-up to detect and treat those recently exposed.