HIV
HIV is a virus that attacks immune cells, but testing, prevention medicines, and antiretroviral treatment can let people live long lives and prevent transmission.
What HIV is
HIV stands for human immunodeficiency virus. It infects cells of the immune system, especially CD4 T cells, and uses those cells to make more virus. Without treatment, HIV can weaken immune defenses over time and progress to AIDS, the most advanced stage of HIV infection.
HIV and AIDS
HIV is the virus; AIDS is a clinical stage that can occur when immune damage is severe or certain opportunistic infections or cancers develop. Modern antiretroviral treatment has changed this story. Many people with HIV who are diagnosed and treated early never develop AIDS.
How HIV spreads
HIV can spread through blood, semen, rectal fluids, vaginal fluids, and breast milk when enough virus reaches another person's bloodstream or mucous membranes. Common routes include sex without effective prevention, sharing injection equipment, birth or breastfeeding exposure, and unsafe blood or medical exposures where screening and infection control are absent.
Testing
Testing is the only way to know HIV status. Different tests look for antibodies, antigen, or viral genetic material, and each has a window period after exposure before it can detect infection. A positive screening result is followed by confirmatory testing, and a new diagnosis should lead quickly to care.
Treatment and viral load
Antiretroviral therapy, or ART, uses medicines that block HIV replication. Treatment lowers viral load, the amount of virus in blood. When a person takes ART as prescribed and maintains an undetectable viral load, they stay healthier and do not transmit HIV sexually, a principle often summarized as U=U.
Prevention medicines
PrEP, or pre-exposure prophylaxis, is medicine for people without HIV who may be exposed through sex or injection drug use. PEP, or post-exposure prophylaxis, is an emergency medicine course started soon after a possible exposure. Both depend on timing, testing, adherence, and clinical guidance.
Pregnancy and breastfeeding
HIV can pass from a pregnant person to a baby during pregnancy, labor, delivery, or breastfeeding, but the risk can be greatly reduced with testing, ART, viral load suppression, infant medicines, and feeding guidance. Local recommendations depend on access to safe alternatives, care systems, and individual health factors.
Public-health control
HIV control combines prevention, testing, treatment access, stigma reduction, harm-reduction services, sexual health care, and support for staying in care. It also intersects with tuberculosis, hepatitis B, hepatitis C, and other infections because immune health and shared transmission risks overlap.
Why it matters
HIV matters because it is a chronic infection shaped as much by access and stigma as by biology. The science is powerful: testing identifies infection, treatment protects health, and viral suppression prevents sexual transmission. The challenge is making those tools reachable and trusted.