Fact sheet
1 February 2012

Key facts

  • The Human Immunodeficiency Virus (HIV) targets the immune system and weakens people's surveillance and defence systems against infections and some types of cancer.
  • HIV is one of the world's most troubling communicable diseases, claiming more than 25 million lives over the past three decades.
  • There were approximately 34 million people living with HIV in 2010.
  • HIV infection can be diagnosed through blood tests detecting presence or absence of antibodies and antigens.
  • A cure for HIV infection has not been found but with effective treatment with antiretroviral drugs, patients can control the virus and enjoy healthy and productive lives.
  • In 2010, around 6.6 million people living with HIV were receiving antiretroviral therapy in low- and middle-income countries, but over 7 million others were waiting for access to treatment.
  • HIV destroys and impairs the function of immune cells, with the effect that infected individuals gradually become immunodeficient.
  • 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 10-15 years to develop. This stage 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.
  • In the first few weeks after initial infection, individuals may experience no symptoms or merely a flu-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, infected people could also develop severe illnesses such as tuberculosis, cryptococcal meningitis, and cancers such as lymphomas and Kaposi's sarcoma, among others.

HIV transmission routes

  • Unprotected anal or vaginal sex with an HIV-infected partner;
  • Mother-to-child transmission during pregnancy, childbirth, or breastfeeding;
  • Transfusion with HIV-infected blood products;
  • Sharing of contaminated injection equipment, tattooing, skin-piercing tools and surgical equipment.
  • Unsafe injections, blood transfusions, medical procedures that involve unsterile cutting or piercing;
  • Accidental needle stick injuries, including among health workers.
  • Individuals cannot become infected through ordinary day-to-day contact such as kissing, hugging, shaking hands, or sharing personal objects, food or water.


  • An HIV test reveals infection status by detecting the presence or absence of antibodies to HIV in the blood.
  • Antibodies are produced by individuals' immune systems to fight off foreign pathogens.
  • Most people have a "window period" of 3 to 12 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.
  • Retesting should be done after three months to confirm test results once sufficient time has passed for antibody production in infected individuals.
  • People are strongly advised to be tested for HIV and appropriate counselling should be provided.
  • HIV test results should be kept confidential, and everyone should receive post-test follow-up care, treatment and prevention measures as appropriate.


  • HIV can be suppressed by combination antiretroviral therapy (ART) consisting of three or more antiretroviral (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 power to fight off infections.
  • With ART, HIV-infected individuals can live healthy and productive lives.
  • An estimated 6.6 million people living with HIV in low- and middle-income countries were receiving ART at the end of 2010. Of these, an estimated 420 000-460 000 were children.
  • This is a 16-fold increase in the number of people receiving ART in developing countries between 2003 and 2010.
Access to ART and prevention of mother-to-children transmission (PMTCT) services

Region Coverage for ART in 2010 Coverage for ART in 2009 Coverage for more effective regimen for PMTCT 2010
Sub-Saharan Africa 49% 41% 50%
Latin America and the Caribbean 63% 60% 59%
East, South, and Southeast Asia 39% 33% 16%
Europe and Central Asia 23% 22% 79%
North Africa and Middle East 10% 9% 4%
Total 47% 39% 48%

Source: 2011 Report on global HIV/AIDS response


Individuals can reduce the risk of HIV infection by limiting exposure to risk factors. Key approaches for HIV prevention include:

  • Condom use. Correct and consistent use of male and female condoms during vaginal or anal sex 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 the sexual transmission of HIV and other sexually transmitted infections (STIs).
  • 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.
  • Pre-exposure prophylaxis (PrEP) for HIV-negative partner. Two trials have demonstrated that a daily dose of antiretroviral drugs tenofovir and tenofovir/emtricitabine taken by an HIV-negative partner is effective in preventing acquisition from an HIV-positive partner. These results are being further investigated by WHO.
  • Post-exposure prophylaxis for HIV (PEP). This method includes immediate use of ARV drugs within the first 72 hours following accidental exposure to HIV in order to prevent infection.
  • PEP is often recommended for health care workers exposed to needle stick injuries in the workplace.
  • PEP also includes counselling, first aid care, HIV testing, and depending on risk level, administering of a 28-day course of antiretroviral drugs with follow-up care.
  • Male circumcision. 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 epidemics with high HIV prevalence and low male circumcision rates.
  • 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.
  • In the absence of any interventions, transmission rates are between 15-45%.
  • MTCT can be fully prevented if both the mother and the child are provided with ART or antiretroviral drug prophylaxis throughout the stages when infection could occur.
  • ART. A new trial has confirmed if an HIV-positive person adheres to an effective antiretroviral therapy regimen, the risk of transmitting the virus to their uninfected sexual partner can be reduced by 96%. WHO is recommending ART as a key part of HIV prevention strategies.
  • 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 HIV prevention and treatment, particularly synthetic substitution therapy for drug users, includes needle/syringe programme, drug dependence treatment, HIV testing and counselling, HIV treatment and care, and access to condoms and management of STIs, tuberculosis and viral hepatitis.

WHO's response

  • Since the beginning of the AIDS epidemic, WHO has led the global health sector response to HIV.
  • As a co-sponsor of the Joint United Nations Programme on AIDS (UNAIDS), WHO takes the lead in the priority areas of HIV treatment and care, and HIV/tuberculosis co-infection, and jointly coordinates with UNICEF the work on prevention of mother-to-child transmission of HIV.
  • In 2011, WHO Member States adopted a new Global health sector strategy on HIV/AIDS for 2011-2015. The strategy outlined four strategic directions to guide actions by WHO and countries for the next five years.
    • Optimize HIV prevention, diagnosis, treatment and care outcomes.
    • Leverage broader health outcomes through HIV responses.
    • Build strong and sustainable health systems.
    • Address inequalities and advance human rights.
  • WHO's core activities on HIV also include:
    • Improving the availability and quality of HIV related medicines and diagnostics tools;
    • Setting norms and standards for scaling up HIV prevention, diagnosis, treatment, care and support services;
    • Monitoring and promoting health-sector progress towards achieving universal access to HIV services;
    • Facilitating cohesion and collaboration among partners to achieve the HIV related Millennium Development Goals and the targets set out in the global health sector strategy on HIV/AIDS, 2011-2015.
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