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HIV/AIDS

Fact sheet N°360
Updated November 2014


Key facts

  • HIV continues to be a major global public health issue, having claimed more than 39 million lives so far. In 2013, 1.5 [1.4–1.7] million people died from HIV-related causes globally.
  • There were approximately 35.0 [33.2–37.2] million people living with HIV at the end of 2013 with 2.1 [1.9–2.4] million people becoming newly infected with HIV in 2013 globally.
  • Sub-Saharan Africa is the most affected region, with 24.7 [23.5–26.1] million people living with HIV in 2013. Also sub-Saharan Africa accounts for almost 70% of the global total of new HIV infections.
  • HIV infection is usually diagnosed through blood tests detecting the presence or absence of HIV antibodies.
  • There is no cure for HIV infection. However, effective treatment with antiretroviral (ARV) drugs can control the virus so that people with HIV can enjoy healthy and productive lives.
  • In 2013, 12.9 million people living with HIV were receiving antiretroviral therapy (ART) globally, of which 11.7 million were receiving ART in low- and middle-income countries. The 11.7 million people on ART represent 36% [34–38%] of the 32.6 [30.8–34.7] million people living with HIV in low- and middle-income countries.
  • Paediatric coverage is still lagging in low- and middle-income countries. In 2013 less than 1 in 4 children living with HIV had access to ART, compared to over 1 in 3 adults.

The Human Immunodeficiency Virus (HIV) targets the immune system and weakens people's surveillance and defence systems against infections and some types of cancer. As the virus destroys and impairs the function of immune cells, infected individuals gradually become immunodeficient. Immune function is typically measured by CD4 cell count. Immunodeficiency results in increased susceptibility to a wide range of infections and diseases that people with healthy immune systems can fight off.

The most advanced stage of HIV infection is Acquired Immunodeficiency Syndrome (AIDS), which can take from 2 to 15 years to develop depending on the individual. AIDS is defined by the development of certain cancers, infections, or other severe clinical manifestations.

Signs and symptoms

The symptoms of HIV vary depending on the stage of infection. Though people living with HIV tend to be most infectious in the first few months, many are unaware of their status until later stages. The first few weeks after initial infection, individuals may experience no symptoms or an influenza-like illness including fever, headache, rash or sore throat.

As the infection progressively weakens the person's immune system, the individual can develop other signs and symptoms such as swollen lymph nodes, weight loss, fever, diarrhoea and cough. Without treatment, they could also develop severe illnesses such as tuberculosis, cryptococcal meningitis, and cancers such as lymphomas and Kaposi's sarcoma, among others.

Transmission

HIV can be transmitted via the exchange of a variety of body fluids from infected individuals, such as blood, breast milk, semen and vaginal secretions. Individuals cannot become infected through ordinary day-to-day contact such as kissing, hugging, shaking hands, or sharing personal objects, food or water.

Risk factors

Behaviours and conditions that put individuals at greater risk of contracting HIV include:

  • having unprotected anal or vaginal sex;
  • having another sexually transmitted infection such as syphilis, herpes, chlamydia, gonorrhoea, and bacterial vaginosis;
  • sharing contaminated needles, syringes and other injecting equipment and drug solutions when injecting drugs;
  • receiving unsafe injections, blood transfusions, medical procedures that involve unsterile cutting or piercing; and
  • experiencing accidental needle stick injuries, including among health workers.

Diagnosis

An HIV test reveals infection status by detecting the presence or absence of antibodies to HIV in the blood. Antibodies are produced by an individual’s immune system to fight off foreign pathogens. Most people have a "window period", usually 3 to 6 weeks, during which antibodies to HIV are still being produced and are not yet detectable.

This early period of infection represents the time of greatest infectivity, but transmission can occur during all stages of the infection. If someone has had a recent possible HIV exposure, retesting should be done after 6 weeks to confirm test results, which enables sufficient time to pass for antibody production in infected individuals.

Testing and counselling

HIV testing should be voluntary and the right to decline testing should be recognized. Mandatory or coerced testing by a health-care provider, authority or by a partner or family member is not acceptable as it undermines good public health practice and infringes on human rights.

Some countries have introduced, or are considering, self-testing as an additional option. HIV self-testing is a process whereby a person who wants to know his or her HIV status collects a specimen, performs a test and interprets the test results in private. HIV self-testing does not provide a definitive diagnosis; instead, it is a screening test for HIV.

All testing and counselling services must include the 5 C’s recommended by WHO: informed Consent, Confidentiality, Counselling, Correct test results and linkage to Care, treatment and other services.

Prevention

Individuals can reduce the risk of HIV infection by limiting exposure to risk factors. Key approaches for HIV prevention, which are often used in combination, include:

1. Male and female condom use

Correct and consistent use of male and female condoms during vaginal or anal penetration can protect against the spread of sexually transmitted infections, including HIV. Evidence shows that male latex condoms have an 85% or greater protective effect against HIV and other sexually transmitted infections (STIs).

2. Testing and counselling for HIV and STIs

Testing for HIV and other STIs is strongly advised for all people exposed to any of the risk factors so that they can learn of their own infection status and access necessary prevention and treatment services without delay. WHO also recommends offering testing for partners or couples.

3. Voluntary medical male circumcision

Medical male circumcision, when safely provided by well-trained health professionals, reduces the risk of heterosexually acquired HIV infection in men by approximately 60%. This is a key intervention in generalized epidemic settings with high HIV prevalence and low male circumcision rates.

4. Antiretroviral (ART) use for prevention

4.1 ART as prevention

A 2011 trial has confirmed if an HIV-positive person adheres to an effective ART regimen, the risk of transmitting the virus to their uninfected sexual partner can be reduced by 96%. For couples in which one partner is HIV-positive and the other HIV-negative, WHO recommends offering ART for the HIV-positive partner regardless of her/his CD4 count.

4.2 Pre-exposure prophylaxis (PrEP) for HIV-negative partner

Oral PrEP of HIV is the daily use of ARV drugs by HIV-uninfected people to block the acquisition of HIV. Studies have demonstrated the effectiveness of PrEP in reducing HIV transmission among serodiscordant heterosexual couples (where one partner is infected and the other is not), men who have sex with men, transgender women, high-risk heterosexual couples, and people who inject drugs. WHO encourages countries to undertake projects to gain experience in implementing PrEP safely and effectively.

In July 2014, WHO released "Consolidated guidelines on HIV prevention, diagnosis, treatment and care for key populations" which recommended PrEP as an additional HIV prevention choice within a comprehensive HIV prevention package for men who have sex with men.

4.3 Post-exposure prophylaxis for HIV (PEP)

Post-exposure prophylaxis (PEP) is the use of ARV drugs within 72 hours of exposure to HIV in order to prevent infection. PEP includes counselling, first aid care, HIV testing, and administering of a 28-day course of ARV drugs with follow-up care.

In its updated guidelines to be issued in December 2014, WHO recommends PEP use for both occupational and non-occupational exposures and for adults and children. The new recommendations provide simpler regimens using ARVs already being used in treatment. The implementation of the new guidelines will enable easier prescribing, better adherence and increased completion rates of PEP to prevent HIV in people who have been accidentally exposed to HIV such as health workers or through unprotected sexual exposures or sexual assault.

5. Harm reduction for injecting drug users

People who inject drugs can take precautions against becoming infected with HIV by using sterile injecting equipment, including needles and syringes, for each injection. A comprehensive package of interventions for HIV prevention and treatment includes:

  • needle and syringe programmes;
  • opioid substitution therapy for people dependent on opioids and other evidence based drug dependence treatment;
  • HIV testing and counselling;
  • HIV treatment and care;
  • access to condoms; and
  • management of STIs, tuberculosis and viral hepatitis.

6. Elimination of mother-to-child transmission of HIV (eMTCT)

The transmission of HIV from an HIV-positive mother to her child during pregnancy, labour, delivery or breastfeeding is called vertical or mother-to-child transmission (MTCT). In the absence of any interventions during these stages, rates of HIV transmission from mother-to-child can be between 15-45%. MTCT can be nearly fully prevented if both the mother and the child are provided with ARV drugs throughout the stages when infection could occur.

WHO recommends options for prevention of MTCT (PMTCT), which includes providing ARVs to mothers and infants during pregnancy, labour and the post-natal period, and offering life-long treatment to HIV-positive pregnant women regardless of their CD4 count.

In 2013, 67% [62–73%] of the estimated 1.4 [1.3-1.6] million pregnant women living with HIV in low- and middle-income countries received effective antiretroviral drugs to avoid transmission to their children, up from 47% in 2009.

Treatment

HIV can be suppressed by combination ART consisting of 3 or more ARV drugs. ART does not cure HIV infection but controls viral replication within a person's body and allows an individual's immune system to strengthen and regain the capacity to fight off infections. With ART, people living with HIV can live healthy and productive lives.

Approximately 11.7 million people living with HIV in low- and middle-income countries were receiving ART at the end of 2013. About 740 000 of those were children.

In 2013, there was a large increase in number of people on ART in low- and middle-income countries --2 million-- in a single year.

Paediatric coverage is still lagging behind with 1 in 4 children on ART, compared to 1 in 3 adults. Of all adults living with HIV, 37% were receiving treatment however just 23% of all children living with HIV were receiving these lifesaving medicines in 2013.

WHO response

As the world moves towards reaching the target date for the Millennium Development Goals, WHO is working with countries to implement the Global Health Sector Strategy on HIV/AIDS for 2011-2015. WHO has identified six operational objectives for 2014–2015 to support countries most efficiently in moving towards the global HIV targets. These are to support:

  • strategic use of ARVs for HIV treatment and prevention;
  • eliminating HIV in children and expanding access to paediatric treatment;
  • an improved health sector response to HIV among key populations;
  • further innovation in HIV prevention, diagnosis, treatment and care;
  • strategic information for effective scale up;
  • stronger links between HIV and related health outcomes.

WHO is a cosponsor of the Joint United Nations Programme on AIDS (UNAIDS). Within UNAIDS, WHO leads activities on HIV treatment and care, HIV and tuberculosis co-infection, and jointly coordinates with UNICEF the work on the elimination of mother-to-child transmission of HIV.

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