Human immunodeficiency virus (HIV) is a retrovirus that can lead to acquire immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections.
Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unprotected sexual intercourse, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth.
Many HIV-positive people are unaware that they are infected with the virus. HIV-1 testing consists of initial screening with an enzyme-linked immunosorbent assay (ELISA) to detect antibodies to HIV-1. Specimens with a nonreactive result from the initial ELISA are considered HIV-negative unless new exposure to an infected partner or partner of unknown HIV status has occurred. Specimens with a reactive ELISA result are retested in duplicate. If the result of either duplicate test is reactive, the specimen is reported as repeatedly reactive and undergoes confirmatory testing with a more specific supplemental test (e.g., Western blot or, less commonly, an immunofluorescence assay (IFA)). Only specimens that are repeatedly reactive by ELISA and positive by IFA or reactive by Western blot are considered HIV-positive and indicative of HIV infection.
There is currently no vaccine or cure for HIV or AIDS. The only known method of prevention is avoiding exposure to the virus. However, an antiretroviral treatment, known as post-exposure prophylaxis, is believed to reduce the risk of infection if begun directly after exposure.
HIV is thought to have originated in non-human primates in sub-Saharan Africa and transferred to humans during the 20th century. The epidemic officially began on 5 June 1981.
Two species of HIV infect humans: HIV-1 and HIV-2. Both species of the virus are believed to have originated in West-Central Africa and jumped species (zoonosis) from a non-human primate to humans.
HIV-1 is thought to have originated in southern Cameroon after jumping from wild chimpanzees to humans during the twentieth century. It evolved from a Simian Immunodeficiency Virus (SIVcpz)
HIV-2, on the other hand, may have originated from the Sooty Mangabey (Cercocebus atys), an Old World monkey of Guinea-Bissau, Gabon, and Cameroon.
Prevention:
Someone can eliminate or reduce their risk of becoming infected with HIV during sex by choosing to:
- Abstain from sex or delay first sex
- Be faithful to one partner or have fewer partners
- Condomise, which means using male or female condoms consistently and correctly
People who share equipment to inject recreational drugs risk becoming infected with HIV from other drug users. Methadone maintenance and other drug treatment programmes are effective ways to help people eliminate this risk by giving up injected drugs altogether.
Needle exchange programmes have been shown to reduce the number of new HIV infections without encouraging drug use. These programmes distribute clean needles and safely dispose of used ones, and also offer related services such as referrals to drug treatment centres and HIV counselling and testing.
Transfusion of infected blood or blood products is the most efficient of all ways to transmit HIV. However, the chances of this happening can be greatly reduced by screening all blood supplies for the virus, and by heat-treating blood products where possible. In addition, because screening is not quite 100% accurate, it is sensible to place some restrictions on who is eligible to donate, provided that these are justified by epidemiological evidence, and don’t unnecessarily limit supply or fuel prejudice. Reducing the number of unnecessary transfusions also helps to minimise risk.
The safety of medical procedures and other activities that involve contact with blood, such as tattooing and circumcision, can be improved by routinely sterilising equipment. An even better option is to dispose of equipment after each use, and this is highly recommended if at all possible.
Health care workers themselves run a risk of HIV infection through contact with infected blood. The most effective way for staff to limit this risk is to practise universal precautions, which means acting as though every patient is potentially infected. Universal precautions include washing hands and using protective barriers for direct contact with blood and other body fluids.
HIV can be transmitted from a mother to her baby during pregnancy, labour and delivery, and later through breastfeeding. The first step towards reducing the number of babies infected in this way is to prevent HIV infection in women, and to prevent unwanted pregnancies.
Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unprotected sexual intercourse, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth.
Many HIV-positive people are unaware that they are infected with the virus. HIV-1 testing consists of initial screening with an enzyme-linked immunosorbent assay (ELISA) to detect antibodies to HIV-1. Specimens with a nonreactive result from the initial ELISA are considered HIV-negative unless new exposure to an infected partner or partner of unknown HIV status has occurred. Specimens with a reactive ELISA result are retested in duplicate. If the result of either duplicate test is reactive, the specimen is reported as repeatedly reactive and undergoes confirmatory testing with a more specific supplemental test (e.g., Western blot or, less commonly, an immunofluorescence assay (IFA)). Only specimens that are repeatedly reactive by ELISA and positive by IFA or reactive by Western blot are considered HIV-positive and indicative of HIV infection.
There is currently no vaccine or cure for HIV or AIDS. The only known method of prevention is avoiding exposure to the virus. However, an antiretroviral treatment, known as post-exposure prophylaxis, is believed to reduce the risk of infection if begun directly after exposure.
HIV is thought to have originated in non-human primates in sub-Saharan Africa and transferred to humans during the 20th century. The epidemic officially began on 5 June 1981.
Two species of HIV infect humans: HIV-1 and HIV-2. Both species of the virus are believed to have originated in West-Central Africa and jumped species (zoonosis) from a non-human primate to humans.
HIV-1 is thought to have originated in southern Cameroon after jumping from wild chimpanzees to humans during the twentieth century. It evolved from a Simian Immunodeficiency Virus (SIVcpz)
HIV-2, on the other hand, may have originated from the Sooty Mangabey (Cercocebus atys), an Old World monkey of Guinea-Bissau, Gabon, and Cameroon.
Prevention:
Someone can eliminate or reduce their risk of becoming infected with HIV during sex by choosing to:
- Abstain from sex or delay first sex
- Be faithful to one partner or have fewer partners
- Condomise, which means using male or female condoms consistently and correctly
People who share equipment to inject recreational drugs risk becoming infected with HIV from other drug users. Methadone maintenance and other drug treatment programmes are effective ways to help people eliminate this risk by giving up injected drugs altogether.
Needle exchange programmes have been shown to reduce the number of new HIV infections without encouraging drug use. These programmes distribute clean needles and safely dispose of used ones, and also offer related services such as referrals to drug treatment centres and HIV counselling and testing.
Transfusion of infected blood or blood products is the most efficient of all ways to transmit HIV. However, the chances of this happening can be greatly reduced by screening all blood supplies for the virus, and by heat-treating blood products where possible. In addition, because screening is not quite 100% accurate, it is sensible to place some restrictions on who is eligible to donate, provided that these are justified by epidemiological evidence, and don’t unnecessarily limit supply or fuel prejudice. Reducing the number of unnecessary transfusions also helps to minimise risk.
The safety of medical procedures and other activities that involve contact with blood, such as tattooing and circumcision, can be improved by routinely sterilising equipment. An even better option is to dispose of equipment after each use, and this is highly recommended if at all possible.
Health care workers themselves run a risk of HIV infection through contact with infected blood. The most effective way for staff to limit this risk is to practise universal precautions, which means acting as though every patient is potentially infected. Universal precautions include washing hands and using protective barriers for direct contact with blood and other body fluids.
HIV can be transmitted from a mother to her baby during pregnancy, labour and delivery, and later through breastfeeding. The first step towards reducing the number of babies infected in this way is to prevent HIV infection in women, and to prevent unwanted pregnancies.
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