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AIDS
Article Free Pass- Introduction
- The emergence of AIDS
- Prevalence and distribution of HIV/AIDS
- The origin of HIV
- Groups and subtypes of HIV
- Transmission
- Life cycle of HIV
- Genome of HIV
- Course of infection
- Diagnosis, treatment, and prevention
- Social, legal, and cultural aspects
- Related
- Contributors & Bibliography
- Year in Review Links
AIDS, byname of acquired immunodeficiency syndrome, transmissible disease of the immune system caused by the human immunodeficiency virus (HIV). HIV is a lentivirus (literally meaning “slow virus”; a member of the retrovirus family) that slowly attacks and destroys the immune system, the body’s defense against infection, leaving an individual vulnerable to a variety of other infections and certain malignancies that eventually cause death. AIDS is the final stage of HIV infection, during which time fatal infections and cancers frequently arise.
The emergence of AIDS
On June 5, 1981, the U.S. Centers for Disease Control and Prevention (CDC) published a report describing a rare lung infection known as Pneumocystis carinii pneumonia in five homosexual men in Los Angeles. Expert review of the cases suggested that the disease likely was acquired through sexual contact and that it appeared to be associated with immune dysfunction caused by exposure to some factor that predisposed the affected individuals to opportunistic infection. The following month the CDC published a report describing an outbreak of cases of a rare cancer called Kaposi sarcoma in homosexual men in New York City and San Francisco. The report noted that in many instances the cancers were accompanied by opportunistic infections, such as P. carinii pneumonia. The infections and cancers were later determined to be manifestations of AIDS. In addition to affecting homosexual men, the disease was detected in intravenous drug users, who became infected mainly by sharing contaminated hypodermic needles.
In 1983 French and American researchers isolated the causative agent, HIV. (In 2008 French virologists Françoise Barré-Sinoussi and Luc Montagnier were awarded the Nobel Prize for Physiology or Medicine for their discovery of HIV.) By 1985 serological tests to detect the virus had been developed.
Prevalence and distribution of HIV/AIDS
According to a 2011 United Nations report on AIDS, an estimated 34 million people were living with HIV, approximately 2.7 million people were newly infected with HIV, and about 1.8 million people died of AIDS and AIDS-related conditions in 2010. Between 1997 and 2010, the annual number of new infections dropped 21 percent, and since about 2005, the annual number of deaths from AIDS has also declined. The latter trend has been due in large part to improved access to treatment for the afflicted. Thus, there has been an increase in the overall number of people living with AIDS. Since 1981, however, more than 25 million people have died of the disease.
People living in sub-Saharan Africa account for about 70 percent of all infections, and in some countries of the region the prevalence of HIV infection of inhabitants exceeded 10 percent of the population. Rates of infection are lower in other parts of the world, but different subtypes of the virus have spread to Europe, India, South and Southeast Asia, Latin America, and the Caribbean. Rates of infection have leveled off somewhat in the United States and Europe. In the United States nearly one million people are living with HIV/AIDS, and half of all new infections are among African Americans. In Asia the sharpest increases in HIV infections are found in China, Indonesia, and Vietnam. Access to retroviral treatment for AIDS remains limited in some areas of the world, although more people are receiving treatment today than in the past.
The origin of HIV
Details of the origin of HIV remain unclear. However, a lentivirus that is genetically similar to HIV has been found in chimpanzees and gorillas in western equatorial Africa. This virus is known as simian immunodeficiency virus (SIV), and it was once widely thought to be harmless in chimpanzees. However, in 2009 a team of researchers investigating chimpanzee populations in Africa found that SIV in fact causes AIDS-like illness in the animals. SIV-infected chimpanzees have a death rate that is 10 to 16 times higher than their uninfected counterparts. The practice of hunting, butchering, and eating the meat of chimpanzees may have allowed transmission of the virus to humans, probably in the late 19th or early 20th century. The strain of SIV found in gorillas is known as SIVgor, and it is distinct from the strain found in chimpanzees. Because primates are suspected to be the source of HIV, AIDS is considered a zoonosis, an infection that is shared by humans and other vertebrate animals.
Genetic studies of a pandemic strain of HIV, known as HIV-1 group M, have indicated that the virus emerged between 1884 and 1924 in central and western Africa. Researchers estimate that this strain of the virus began spreading throughout these areas in the late 1950s. Later, in the mid-1960s, an evolved strain called HIV-1 group M subtype B spread from Africa to Haiti. In Haiti this subtype acquired unique characteristics, presumably through the process of genetic recombination. Sometime between 1969 and 1972, the virus migrated from Haiti to the United States. The virus spread within the United States for about a decade before it was discovered in the early 1980s. The worldwide spread of HIV-1 was likely facilitated by several factors, including increasing urbanization and long-distance travel in Africa, international travel, changing sexual mores, and intravenous drug use.
- Introduction
- The emergence of AIDS
- Prevalence and distribution of HIV/AIDS
- The origin of HIV
- Groups and subtypes of HIV
- Transmission
- Life cycle of HIV
- Genome of HIV
- Course of infection
- Diagnosis, treatment, and prevention
- Social, legal, and cultural aspects
- Related
- Contributors & Bibliography
- Year in Review Links
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