How HIV Spreads

laboratory microscope lens in a labInfection with the human immunodeficiency virus (HIV) is a serious concern, but the risk of transmitting the virus to another person by everyday, non-sexual contact is very low.

HIV lives in a person’s bodily fluids, primarily blood, semen, or vaginal fluids, and a person generally can become infected with HIV in one of three ways:

Having sex with an infected person. Anal, vaginal, and oral sex all pose risks for HIV transmission. Men who have sex with other men accounted for about half of the estimated 56,300 adults and teenagers diagnosed with HIV in the United States in 2006, according to the latest estimates from the U.S. Centers for Disease Control and Prevention (CDC). Another third of those diagnosed were infected through high-risk heterosexual contact.

Using needles or syringes that have been used by a person with HIV. Injection drug use was responsible for the transmission of about 13 percent of all adult HIV infections in 2006, according to the CDC.

Exposure of a fetus or infant to a mother with HIV. HIV positive pregnant women can infect their babies with HIV before birth, during delivery, and after birth while breastfeeding. To prevent babies from becoming infected while they’re still in the womb, doctors can treat a pregnant HIV-positive woman with antiretroviral drugs. A caesarean section performed before labor starts and before a woman’s water breaks can help prevent a baby from getting the virus during the birthing process. Completely avoiding breastfeeding eliminates this third possible method of transmission of the virus from mother to baby.