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Max Roser and Hannah Ritchie (2018) - "HIV / AIDS". Published online at Retrieved from: '' [Online Resource]
This article was first published in November 2014; last revised in April 2018.

HIV (human immunodeficiency virus) is a lentivirus which can lead to acquired immunodeficiency virus (AIDS). AIDS in humans results in a gradual and persistent decline and failure of the immune system, resulting in heightened risk of life-threatening infection and cancers.

In the majority of cases, HIV is a sexually-transmitted infection. However, HIV can also be transmitted from a mother to her child, during pregnancy or childbirth (through blood or fluid exposure), or through breastfeeding. Non-sexual transmission can also occur through the sharing of injection equipment such as needles.

This entry presents a global overview the HIV and AIDS epidemics, presenting data on prevalence, deaths, transmission, treatment and connected impacts on life expectancy, discrimination and education.

I. Empirical View

The 1990s saw a substantial increase in the number of people infected with HIV and dying of AIDS. In 1997, almost 3.5 million people were diagnosed with HIV per year. After 1997, the number of new diagnoses began to decline and in 2015 it was reduced to 2.1 million per year.

The number of AIDS-related deaths increased throughout the 1990s and reached a peak in 2004, 2005 when in both years 2 million people died. Since then the annual number of deaths from AIDS declined as well and a decade later it was almost halved when 1.1 million people died in 2015.

The chart also shows the continuing increase in the number of people living with HIV. The rate of increase has slowed down compared to the 1990s but the absolute number reached a peak in 2015 when 36.7 million people were living with HIV globally.

Global number of AIDS-related deaths, new HIV Infections, and People living with HIV (1990-2015)1


I.1 People with HIV/AIDS

Prevalence of HIV/AIDS

In the chart below you can see how adult HIV prevalence has changed with time, by clicking the play button on the bottom left. Data from both the UNAIDS/World Bank and IHME, Global Burden of Disease are shown in the two charts below.

Overall, prevalence increased until the mid 2000s, where it peaked globally and has since declined. Southern Africa remains the world region with the highest prevalence. In 2015 Botswana had the highest prevalence: 22 percent of 15-49 year olds had HIV.

Number of people with HIV

In the charts below we see the number of people with HIV by region and by country. In 2016 more than 36 million had HIV globally; 72 percent were based in Sub-Saharan Africa. In terms of the absolute number of people with HIV, South Africa had the greatest number in 2016 with more than 6.3 million.

I.2 New Infections

Number of new infections per year

There are two vital components to addressing the global HIV epidemic: treatment of those with HIV and the prevention of further transmission. The charts below show the number of new HIV infections of HIV per year.

As shown, the total number of new infections per year peaked globally in 1997 at 3.5 million and has since declined to 2.1 million.

HIV incidence

0.05% of the world population are currently (2015 data) newly infected with HIV every year. This incidence of HIV was halved from 0.1% in the mid 1990s.

The distribution of these new cases is not even across different regions. While in Asian and Latin American countries the incidence is well below 0.1% there are some countries with much higher incidence. In South Africa 1.44% of the previously uninfected population was infected with HIV in 2015.

Fortunately, the number of new cases in Sub-Sarharan Africa and other world regions has now been steadily decreasing each year.

I.3 Deaths from AIDS

HIV/AIDS deaths by age group

The visualisation below shows the annual number of deaths from HIV/AIDS, differentiated by age group. Note that this data can be viewed for any country in the interactive chart features below.

Globally we see a clear rise-peak-decline trend in HIV-related deaths. In 1990, the total number of deaths is estimated to be approximately 290,000; this increased to peak in 2005/06 at approximately 1.9 million. Since then, the total number of deaths has almost halved, falling to around 1 million in 2016.

Across this period, 15-49 year olds have maintained the highest (and a consistent) share of around 74-75 percent of global deaths from HIV/AIDS.

HIV/AIDS death rates

The chart below shows HIV/AIDS age-standardized death rates (measured as the number of deaths per 100,000 people) across the world over this period.

HIV/AIDS death rates by age

The visualisation below shows the breakdown of death rates from HIV/AIDS (measured as the number of deaths per 100,000 individuals) by age category.

I.4 HIV and children

Children living with HIV

In children with HIV, transmission has typically occurred from the mother (mother-to-child-transmission; MTCT) either during pregnancy or childbirth, or through breastfeeding. The charts below shows the total number of children aged 14 years old and under who are living with HIV. Globally the number of children living with HIV peaked in 2007-2008 at approximately 2.3 million. This has since declined to 1.8 million in 2015.

New HIV infections of children

The visualisation below shows the total number of children newly infected with HIV each year. Globally — with similar trends at national levels — the number of new infections in children peaked around the early 2000s (globally at 500,000 new infections per year) followed by a rapid decline over the last decade. In 2015 an estimated 150,000 new children were infected with HIV.

Orphaned children from AIDS

'Orphaned' children are defined as those who have lost either one or both parents from AIDS. This does not necessarily imply that children orphaned by AIDS have HIV themselves (although in some cases HIV has been transmitted from mother-to-child). The chart below shows the number of children (aged 17 and under) orphaned from AIDS deaths.

I.5 HIV, AIDS and gender

There are differences in both the prevalence of HIV and death rates from AIDS between men and women. The charts below show both the differences in prevalence between males and females, and the differences in AIDS-deaths.

As seen, HIV prevalence tends to be higher in women across Sub-Saharan Africa, although higher in males across most other regions. The trend in AIDS-related deaths shows the opposite: more men tend to to die from AIDS every year than women. The reasons for differences in prevalence and death rates are complex; however, in general, across Sub-Saharan Africa women tend to be infected with HIV earlier than men and survive longer (explaining both the higher prevalence and lower annual AIDS deaths in women). There are a number of gender inequality and social norm issues which result in higher prevalence of HIV in females across many countries; women are at greater risk when they have a limited role in sexual decision-making and protection, role rates of sexual education and higher rates of transactional sex and 2

Differences of HIV prevalence between men and women

Differences in AIDS deaths in men and women

II. Correlates, Determinants, & Consequences

II.1 Antiretroviral Medicine & Treatment

Reducing the impact of the HIV epidemic requires the prevention of further transmission, as well as treatment for those already living with HIV. Antiretroviral therapy (ART) is highly active in suppressing viral replication, reducing the amount of the virus in the blood to undetectable levels and slowing the progress of HIV disease.

The charts below show the number of people receiving antiretroviral therapy (ART), the coverage of pregnant women receiving ART for the prevention of mother-to-child transmission (PMTCT), and the gap in coverage for those living with HIV.

Antiretroviral Therapy (ART)

Deaths averted from antiretroviral therapy (ART)

Antiretroviral therapy (ART) has been critical in reducing the number of deaths from AIDS. In the chart below we see the number of deaths from AIDS, as well as the number of deaths averted as a result of ART. Globally, 1.2 million deaths in 2016 were averted as a result of ART - this is greater than the 1 million deaths which occurred. Without ART, global deaths from AIDS would be more than double their current annual figures.

In South Africa, ART has been crucial in reducing death rates from AIDS. Approximately three-quarters of potential deaths from AIDS were averted in 2016 as a result of ART.

Deaths averted from HIV programmes

Deaths averted from AIDS can result from both treatment (ART) and prevention of HIV transmission. The chart below shows recent data of the estimated number of deaths averted as a result of all HIV programmes, which includes treatment and prevention of transmission such as through education & contraceptive programmes.

II.2 HIV Transmission Prevention

The majority of HIV infections are transmitted through sexual activity. Sexual transmission can be prevented through condom use (both in heterosexual and homosexual relationships). In the charts below we see the prevalence of condom use, particularly in cases of 'high-risk sex', which is that with a non-marital, non-cohabiting sexual partner.

II.3 Mother to Child Infection

Mother to child transmission of HIV is one of the leading causes of HIV spread. Fortunately, in all Sub-Saharan African regions, mother-to-child transmission has decreased. For Eastern and Southern Africa, the decrease has been dramatic, while Western and Central Africa have see periods of increased transmission, though the percentage is still lower than it was in 2003.

Trends in mother-to-child transmission rates by subregion in sub-Saharan Africa, 2000-2011 – UNAIDS (2012)3

Trends in mother-to-child transmission rates by subregion in sub-Saharan Africa, 2000-2011 – UNAIDS (2012)

II.4 Education and HIV/AIDS

Education about HIV/AIDS is an incredibly important factor to prevent the disease's spread. Unfortunately often knowledge about HIV/AIDS much lower for students of low socioeconomic status than students with high status.

Percentage of grade 6 pupils who achieved minimal level of HIV and AIDS knowledge by socio-economic status, 2007 – UNESCO (2012)4

Percentage of grade 6 pupils who achieved minimal level of HIV and AIDS knowledge by socio-economic status, 2007 – UNESCO (2012)

The more education pregnant women have received, the more likely they are to seek HIV testing during their antenatal care visits.

Percentage of pregnant women who, when it was offered during an antenatal care visit, sought HIV testing and received their results, by education, selected sub-Saharan African countries, 2004-2007 – UNESCO (2011)5

Percentage of pregnant women who, when it was offered during an antenatal care visit, sought HIV testing and received their results, by education, selected sub-Saharan African countries, 2004-2007 – UNESCO (2011)

Increases in education lead to safer behaviors. In both Kenya and the Dominican Republic, higher education level is correlated with higher condom usage. Even having only part of a primary education leads to a massive increase in the percentage of people who know that condoms prevent the spread of HIV.

Education and condom usage in Kenya and the Dominican Republic – World Development Report (2007)6

Knowing that condoms prevent HIV increases with education, but so does the gap between knowledge and behavior.

Education and condom usage in Kenya and the Dominican Republic – World Development Report (2007)

II.5 HIV impacts on life expectancy

The following chart shows that while globally life expectancy has been increasing since the 1950s, several countries in Sub-Saharan Africa saw a major decrease in life expectancy with the onset of the AIDS crisis around 1990. Life expectancy has started to increase again since the early 2000s, but for many of the countries shown, levels have not yet returned to life expectancies prior to the AIDS crisis.

II.6 Tuberculosis among People Living with HIV

Tuberculosis (TB) is the leading HIV-associated opportunistic infection in low- and middle- income countries, and it is a leading cause of death globally among people living with HIV. Death due to tuberculosis still remains high among people living with HIV, however the number of deaths is decreasing. Most of the global mortality due to TB among those with HIV is from cases in Sub-Saharan Africa.

In the charts below we see the number of tuberculosis (TB) patients who tested positive for HIV; the number receiving antiretroviral therapy (ART); and the number of TB-related deaths among those living with HIV.

II.7 Resources Available to Spend on HIV/AIDS

The following chart shows international and domestic spending on HIV, broken down by donor, and region in low- and middle-income countries. Globally investment in HIV treatment and prevention was approximately US$19 billion. Also shown is the estimated funding requirements through to 2030; it's expected that approximately US$25-26 billion per year will be required to meet future requirements of treatment and prevention programmes.

Previously, we have seen that AIDs deaths are still steadily increasing in the Middle East and North Africa, which may partially be due to the lack of domestic resources placed on ART therapy in this region.

II.8 Discriminatory attitudes to those with HIV

Discrimination towards those living with HIV remains common in many countries. High-coverage data on discrimination is scarce, however in the charts below we see the share of the population with discriminatory attitudes across a number of countries. This was assessed by the use of surveys which asked the question: "Would you buy fresh vegetables from a shopkeeper or vendor if you knew that this person had HIV?". The presented figures show the share of respondents (who had previously heard of HIV) who said they would not buy from a vendor with HIV.

In a number of countries more than half of respondents showed discriminatory attitudes. In Guinea, this share was as high as 80 percent.

III. Data Quality & Definition

III.1 Terminology and Definitions

The following terminology and definitions are sourced from the UNAIDS organization.7

HIV: Human Immunodeficiency Virus. HIV is a virus that weakens the immune system, ultimately leading to AIDS.

AIDS: acquired immunodeficiency syndrome.

Antiretroviral medicines/ Antiretrovirals (ARVs)/ Antiretroviral therapy (ART)/ HIV treatment: "Antiretroviral therapy is highly active in suppressing viral replication, reducing the amount of the virus in the blood to undetectable levels and slowing the progress of HIV disease. The usual antiretroviral therapy regimen combines three or more different medicines, such as two nucleoside reverse transcriptase inhibitors (NRTI) and a protease inhibitor, two nucleoside analogue reverse transcriptase inhibitors and a non-nucleoside reverse transcriptase inhibitor (NNRTI), or other combinations.

More recently, entry inhibitors and integrase inhibitors have joined the range of treatment options. Suboptimal regimens are monotherapy and dual therapy. The term highly active antiretroviral therapy was commonly used after the demonstration of excellent virological and clinical response to combinations of three (or more) antiretroviral medicines. Highly active is not needed as a qualification, however, and the term is no longer commonly used.

ARV refers to antiretroviral medicines. It should only be used when referring to the medicines themselves and not to their use."

ARV-based prevention: "ARV-based prevention includes the oral or topical use of antiretroviral medicines to prevent the acquisition of HIV in HIV-negative persons (such as the use of pre-exposure prophylaxis or post-exposure prophylaxis) or to reduce the transmission of HIV from people living with HIV (treatment as prevention)."

Epidemic: "An epidemic refers to a disease condition affecting (or tending to affect) a disproportionately large number of individuals within a population, community or region at the same time. The population may be all of the inhabitants of a given geographic area, the population of a school or similar institution or everyone of a certain age or sex (such as the children or women of a region). An epidemic may be restricted to one locale (an outbreak), be more general (an epidemic) or be global (a pandemic). Common diseases that occur at a constant but relatively high rate in the population are said to be endemic."

HIV-negative (seronegative): "A person who is HIV-negative (also known as seronegative) shows no evidence of HIV in a blood test (e.g. there is an absence of antibodies against HIV). The test result of a person who has acquired HIV but is in the window period between HIV exposure and detection of antibodies also will be negative."

HIV-positive (seropositive): "A person who is HIV-positive (or seropositive) has had antibodies against HIV detected in a blood test or gingival exudate test (commonly known as a saliva test). Results may occasionally be false-positive, especially in infants up to 18 months of age who are carrying maternal antibodies."

Incidence: "HIV incidence is expressed as the number of new HIV infections over the number of people susceptible to infection in a specified time period. Cumulative incidence may be expressed as the number of new cases arising in a given period in a specified population. UNAIDS reports the estimated number of incident cases that occurred in the past year among people aged 15–49 years and 0–14 years."

Mother-to-child transmission (MTCT): "MTCT is the abbreviation for mother-to-child transmission. PMTCT, the abbreviation for prevention of mother-to-child transmission, refers to a four-prong strategy for stopping new HIV infections among children and keeping their mothers alive and families healthy. The four prongs are: helping reproductive-age women avoid HIV (prong 1); reducing unmet need for family planning (prong 2); providing antiretroviral medicine prophylaxis to prevent HIV transmission during pregnancy, labour and delivery, and breastfeeding (prong 3); and providing care, treatment and support for mothers and their families (prong 4).

PMTCT often is mistakenly used to refer to only prong 3— the provision of antiretroviral medicine prophylaxis. Some countries prefer to use the terms parent-to-child transmission or vertical transmission as more inclusive terms to avoid stigmatizing pregnant women, to acknowledge the role of the father/male sexual partner in transmitting HIV to the woman and to encourage male involvement in HIV prevention. Still other countries and organizations use the term elimination of mother-to-child transmission (eMTCT)."

Prevalence: "Usually given as a percentage, HIV prevalence quantifies the proportion of individuals in a population who are living with HIV at a specific point in time. HIV prevalence also can refer to the number of people living with HIV. UNAIDS normally reports HIV prevalence among people aged 15–49 years."

Tuberculosis (TB): "Tuberculosis (TB) is the leading HIV-associated opportunistic infection in low- and middle- income countries, and it is a leading cause of death globally among people living with HIV. The term HIV-associated tuberculosis or HIV-associated TB should be used, rather than the shorthand HIV/TB, in order to distinguish such instances from tuberculosis per se.

The main strategies to reduce the burden of HIV in TB patients are HIV testing (for people whose HIV status is unknown) and the provision of antiretroviral therapy and cotrimoxazole preventive therapy (CPT) (for people living with HIV). The main activities to reduce TB among people living with HIV are regular screening for TB among people in HIV care and the provision of isoniazid preventive therapy (IPT) and ART to HIV-positive people without active TB who meet eligibility criteria."

III.2 Comparisons of UNAIDS and IHME estimates

A number of sources publish estimates on HIV and AIDS - two of the most established (which are presented in this entry) are UNAIDS and the Institute of Health Metrics and Evaluation (IHME), Global Burden of Disease. In the charts below we show the relationship/consistency in estimates of prevalence between these two sources.

Prevalence of HIV

Incidence/new cases of HIV

IV. Data Sources

Joint United Nations Program on HIV and AIDS (UNAIDS)
  • Data: Data on size of epidemic and response
  • Geographical coverage: Global
  • Time span: 1990-2014
  • Available at: Online here
  • There are also tools to analyze the data online, and there is background information on the data and the disease.
World Health Organization
  • Data: Data on size of epidemic and response
  • Geographical coverage: WHO member nations
  • Time span: Since c. 2001
  • Available at: The WHO publishes data here.
Institute of Health Metrics and Evaluation (IHME), Global Burden of Disease (GBD)
  • Data: Death rates & absolute number of deaths from HIV/AIDS
  • Geographical coverage:Global, across all regions and countries
  • Time span:Available from 1990 onwards
  • Available at: Online here
  • Data: HIV/AIDS prevalence and mortality
  • Geographical coverage: Global
  • Time span: Mostly 1990-2011, but some data goes back as far as 1980
  • Available at: Here are data on the share of adults with AIDS.
  • Gapminder also published an extensive documentation of their data, which is online here.
USAID Demographic and Health Surveys
  • Data: Survey data
  • Geographical coverage: Global
  • Time span: Since the 1980s for some countries
  • Available at: Online here
United States Census Bureau in partnership with USAID
  • Data: Data on prevalence and incidence
  • Geographical coverage: Global
  • Time span: Since 1980s for some countries
  • Available at: Online here