Overview
Human immunodeficiency virus (HIV) is an infection that attacks the body’s immune system. Acquired immunodeficiency syndrome (AIDS) is the most advanced stage of the disease.
HIV targets the body’s white blood cells, weakening the immune system. This makes it easier to get sick with diseases like tuberculosis, infections and some cancers.
HIV is spread from the body fluids of an infected person, including blood, breast milk, semen and vaginal fluids. It is not spread by kisses, hugs or sharing food. It can also spread from a mother to her baby.
HIV can be treated and prevented with antiretroviral therapy (ART). Untreated HIV can progress to AIDS, often after many years.
WHO now defines Advanced HIV Disease (AHD) as CD4 cell count less than 200cells/mm3 or WHO stage 3 or 4 in adults and adolescents. All children with HIV younger than 5 years of age are considered to have advanced HIV disease.
Information presented on this page has been replicated from the linked WHO fact sheet. Please always refer to the original source on who.int for the latest version. Last update: March 2024
