Historical Pandemic

HIV/AIDS

Also known as: Acquired Immunodeficiency Syndrome

Death toll

~42 million cumulatively since 1981; ~600,000 annually

Period

1981–present

Pathogen

Human Immunodeficiency Virus (HIV-1 and HIV-2)

Transmission

Sexual contact, blood, mother-to-child (perinatal and breastfeeding), shared needles

Overview

HIV/AIDS emerged as a distinct clinical entity in 1981 when the US CDC reported an unusual cluster of Pneumocystis pneumonia and Kaposi's sarcoma in otherwise-healthy young gay men. The causative virus, HIV, was identified in 1983. Molecular evidence traces HIV-1 to cross-species transmission from chimpanzees in Cameroon around 1920, with spread accelerating in post-colonial Africa before the 1981 recognition.

HIV attacks CD4+ T cells of the immune system. Untreated, it causes progressive immunodeficiency over about 10 years, leaving the body vulnerable to opportunistic infections (tuberculosis, pneumocystis, cytomegalovirus) and certain cancers. Before effective treatment, AIDS was nearly universally fatal within a decade of infection.

Antiretroviral therapy (ART) transformed HIV from a death sentence into a manageable chronic condition. Highly active antiretroviral therapy (HAART) became standard in 1996 and reduced mortality in treated patients by roughly 85%. Pre-exposure prophylaxis (PrEP) offers protection to uninfected high-risk individuals. As of 2024 roughly 39 million people are living with HIV; about 30 million have access to ART.

The pandemic is concentrated in sub-Saharan Africa, particularly southern Africa. In some countries — Eswatini, Lesotho, Botswana — adult HIV prevalence exceeds 20%. Perinatal transmission has been nearly eliminated in high-income countries through universal screening and treatment of pregnant women.

Geographic scope

Global; concentrated in sub-Saharan Africa (~2/3 of cases)

Peak year

2005

Timeline

c. 1920
HIV-1 emerges from chimpanzee SIV in Cameroon (molecular dating).
1981
CDC reports unusual disease cluster in Los Angeles — recognised as new disease.
1983
HIV isolated and identified at Institut Pasteur and the US National Cancer Institute.
1987
First approved antiretroviral drug (AZT) reaches market.
1996
Protease inhibitors and HAART transform treatment; mortality drops sharply.
2003
PEPFAR launched by the US government; global ART access expands.
2005
Peak global AIDS mortality: approximately 2 million deaths per year.
2012
Pre-exposure prophylaxis (PrEP) approved for HIV prevention.
2022
Long-acting injectable ART approved; adherence simplified.

Impact

HIV/AIDS caused an estimated 42 million cumulative deaths and reshaped medical practice, public health, and social movements. It drove the largest global-health funding mobilisation in history (PEPFAR, the Global Fund, UNAIDS). The pandemic accelerated LGBTQ+ political organisation, reshaped medical research ethics, and produced new templates for patient advocacy. In southern Africa, HIV reduced life expectancy by 20 years at its peak before ART expansion reversed the decline. Scientific responses — antiretrovirals, PrEP, rapid testing, and near-elimination of mother-to-child transmission — rank among the 20th and 21st centuries' major medical achievements.

How it ended

Not ended. HIV remains incurable in general, though a small number of patients have been functionally cured through bone marrow transplants from donors with natural HIV resistance. Antiretroviral therapy suppresses viral replication but must be taken lifelong. UNAIDS targets aim to end AIDS as a public-health threat by 2030, defined as reducing new infections and AIDS deaths by 90% from 2010 levels.