What are the routes of HIV transmission?

HIV transmission occurs exclusively through direct contact with certain infectious bodily fluids from a person living with HIV who has a detectable viral load. These fluids include blood, semen (including pre-seminal fluid), vaginal fluids, rectal fluids, and breast milk. Transmission requires the virus to enter the bloodstream or mucous membranes—such as those in the vagina, rectum, mouth, or eyes—or through broken skin.

The primary routes of HIV transmission are: unprotected sexual intercourse (vaginal or anal) with an HIV-positive individual; sharing needles, syringes, or other injection equipment contaminated with HIV-infected blood; mother-to-child transmission during pregnancy, childbirth, or breastfeeding (also known as perinatal transmission); and, rarely, through transfusion of HIV-contaminated blood or blood products—though this risk is now exceedingly low in countries with rigorous blood screening protocols.

It is critical to emphasize that HIV is not transmitted through casual contact. The virus cannot survive outside the human body for long and is not spread by air, water, saliva, tears, sweat, hugging, shaking hands, sharing food or utensils, toilet seats, swimming pools, or insect bites. Additionally, people living with HIV who maintain an undetectable viral load through consistent antiretroviral therapy (ART) have effectively no risk of sexually transmitting the virus—a concept supported by extensive clinical evidence and known as “Undetectable = Untransmittable” (U=U).