AIDS

Introduction & Top Questions
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
- Tests and screening
- Antiretroviral medications
- Condoms, vaccines, gels, and other prevention methods
- Reported cures
HIV and pregnancy
Social, legal, and cultural aspects

References & Edit History Quick Facts & Related Topics

Images, Videos & Interactives

Global trends in new HIV infections and HIV-related deaths

1981 CDC report describing a rare infection later linked to AIDS

How HIV and AIDS Redefined the Fight Against Infectious Diseases

At a Glance

AIDS summary

Quizzes

44 Questions from Britannica’s Most Popular Health and Medicine Quizzes

Related Questions

Can HIV spread through coughing or sneezing?
Can HIV spread through hugging or shaking hands?
How can HIV pass from a parent to a baby?
How did ACT UP influence AIDS treatment and drug approval?
How did PEPFAR expand HIV/AIDS treatment and prevention in low-income countries?
How did Robert Gallo confirm that HIV causes AIDS?
How did highly active antiretroviral therapy change HIV/AIDS outcomes in the 1990s?
How do antiretroviral drugs control HIV infection?
How do integrase inhibitors interfere with HIV replication?
How do protease inhibitors interfere with HIV replication?
How does HIV damage the immune system?
How does HIV differ from AIDS?
How does World AIDS Day raise awareness about HIV and AIDS?
How does antiretroviral therapy reduce mother-to-child HIV transmission?
How does reverse transcriptase help HIV reproduce inside a host cell?
How does the loss of CD4 T cells lead to AIDS?
How is HIV transmitted through bodily fluids?
What does an undetectable HIV viral load mean for sexual transmission?
What symptoms can occur during primary HIV infection?
What were the first recognized AIDS cases in the United States?
When did HIV-1 group M likely emerge in Africa?
Which immune cells does HIV target?
Why are combinations of antiretroviral drugs used to treat HIV?
Why are people with AIDS vulnerable to certain cancers?
Why can HIV antibody tests be negative soon after infection?
Why can HIV infection have few symptoms for many years?
Why did Ryan White become an important figure in AIDS education?
Why did the early AIDS outbreak create stigma toward gay men?
Why do HIV treatment and prevention access vary between different regions of the world?
Why does sharing needles increase the risk of HIV transmission?
Why has sub-Saharan Africa been especially affected by HIV/AIDS?
Why is the red ribbon a symbol of AIDS awareness?
Why was AIDS initially called GRID?
Why was the AIDS Memorial Quilt created?
What is COVID-19?
How does COVID-19 spread?
What symptoms can COVID-19 cause?
How can the risk of COVID-19 transmission be reduced?
Why have COVID-19 variants helped COVID-19 continue to spread?
What is mpox?
How does a person become infected with hepatitis B?
What happens when a person tests positive for hepatitis B?
Does hepatitis B go away completely?
How long can a hepatitis B patient live?

Health & Medicine Conditions & Diseases Immune System Disorders

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External Websites

National Institute of Health - HIVinfo - HIV and AIDS: The Basics
NHS - HIV and AIDS
NPR - Kenneth Kaunda and AIDS
Patient - HIV and AIDS
Healthline - A Comprehensive Guide to HIV and AIDS
UCSF Health - AIDS
National Center for Biotechnology Information - PubMed Central - HIV/AIDS epidemiology, pathogenesis, prevention, and treatment
Mayo Clinic - HIV/AIDS
Centers for Disease Control and Prevention - About HIV
Verywell Health - HIV/AIDS
Harvard Health Publishing - HIV/AIDS
Healthdirect - HIV infection and AIDS
HIV.gov - A Timeline of HIV and AIDS
Baylor College of Medicine - Department of Molecular Virology and Microbiology - HIV (AIDS)

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

AIDS (acquired immunodeficiency syndrome) - Student Encyclopedia (Ages 11 and up)

HIV Scanning electron micrograph of HIV-1 virions (green) budding from a cultured lymphocyte. Multiple round bumps on the cell surface represent sites of virion assembly and budding.

AIDS

disease

Also known as: HIV Stage III, acquired immune deficiency syndrome, acquired immunodeficiency syndrome, slim(Show More)

Written by

Annie Dude

Contributor to SAGE Publications's Encyclopedia of Global Health (2008) whose work for that encyclopedia formed the basis of her contributions to Britannica.

Annie DudeAll

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Nov. 3, 2026 •History

AIDS, infectious disease caused by 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. Progressive deterioration of immune function leaves the affected 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...

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