How Is HIV Transmitted?
HIV is transmitted when the virus enters the body, usually by infected immune cells in blood, vaginal fluids, or semen. Having the following risk factors increases the chance a person may become infected with HIV.
- Sex with an infected partner without using a condom or other barrier protection can transmit HIV. The virus can enter the body through the lining of the vagina, vulva, penis, rectum, or mouth during sex. Anal intercourse, followed by vaginal intercourse, are the primary risk factors. Oral sex is less likely to transmit HIV, but studies have shown that it can transmit both HIV and other sexually transmitted diseases (STDs).
- Most sexual transmission occurs between males and females or from male to male. Case reports of female-to-female transmission of HIV are rare.
- Injection-drug use with shared needles or syringes that are contaminated with blood from an infected person are another way the virus is spread.
- Mother-to-baby transmission during pregnancy or birth, when infected maternal cells enter the baby's circulation, or through breastfeeding, is also a method of transmission.
- Health-care providers in health-care settings may be infected through accidental needle sticks or contact with contaminated fluids. This accounts for only 0.3% of HIV transmission.
- Rarely, transfusion of contaminated blood or blood components can transmit HIV. All blood products in the U.S. are screened to minimize this risk.
- If tissues or organs from an infected person are transplanted, the recipient may acquire HIV. Because donors are screened for HIV routinely in the United States, this is quite rare.
- People who already have a sexually transmitted infection, such as syphilis, genital herpes, chlamydia, human papillomavirus (HPV), gonorrhea, or bacterial vaginosis, are more likely to acquire HIV infection during sex with an infected partner.
- In general, the higher the level of HIV in the blood (the viral load), the more likely that person is to transmit HIV. People who have HIV but have a very low or undetectable viral load (because they are on HIV medicines) are much less likely to transmit HIV. So taking HIV medication is one way to reduce the risk of infecting others. Still, HIV may be present in genital fluids in levels enough to transmit.
HIV cannot survive more than a few minutes outside the body. The virus does not spread through casual contact such as preparing food, sharing towels and bedding, or via swimming pools, telephones, sneezing, or toilet seats. Transmission through kissing alone is extremely rare.
Because of licensing and public-health inspection, it is unlikely to get HIV by getting a tattoo in a commercial shop. However, it is possible to get HIV from a reused or not properly sterilized tattoo or piercing needle or other equipment, or from contaminated ink. So it's important to know that your tattoo artist is licensed, working in a licensed and inspected facility, and posts information about their equipment sterility and procedures.
Last Reviewed 8/31/2017
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