The human immunodeficiency virus (HIV) is a pathogen that attacks and suppresses the immune system, particularly by impairing white blood cells.
The virus can be transmitted (a) sexually – through unprotected sexual intercourse, (b) via blood – for example, by sharing needles – and (c) vertically – from mother to child during pregnancy, childbirth, and, less commonly, through breastfeeding.
Without specific treatment, the virus severely weakens the immune system of the affected person, which can lead to the development of acquired immunodeficiency syndrome (AIDS). This is a syndrome that can occur in people with HIV several years after infection, when the immune system's performance dramatically declines and the body loses its ability to fight even the most common infections.
The onset of AIDS can be prevented by early, appropriate antiretroviral therapy.
