How Is HIV Transmitted?
Summary
- HIV is spread by direct contact with certain body fluids from a person with HIV, like blood or semen.
- People living with HIV can prevent spreading the virus by taking HIV medicine and keeping an undetectable viral load.
What Is HIV?
HIV (human immunodeficiency virus) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and diseases. There is not yet a cure for HIV, so once you have it, you have it for life.
How Is HIV Spread?
HIV spreads through specific body fluids:
- Blood
- Semen (cum) and pre-seminal fluid (pre-cum)
- Rectal fluids
- Vaginal fluids
- Breast milk
For HIV to spread from person to person, also called transmission, the HIV in these fluids must get into the bloodstream of an HIV-negative person. This can happen through certain sexual activities, through open cuts or sores, or from a needle or syringe.
In the United States, HIV is most commonly spread through having vaginal (male-to-female) or anal (male-to-male or male-to-female) sex with a person living with HIV without taking steps to reduce the risk of getting or transmitting HIV. Around 89% of all new HIV diagnoses in the United States are from sexual transmission. There is more risk associated with anal sex than with vaginal sex.
There is still a risk of HIV being spread through certain other activities or situations, including the following:
- Transmission during pregnancy, birth, or breastfeeding. The use of HIV medicines and other prevention and treatment strategies have helped lower the risk of perinatal transmission of HIV to less than 1% in the United States.
- Workplace transmission, such as being exposed to HIV through a needlestick or sharps injury. This risk mainly affects health care workers, and the risk is very low.
HIV is spread only in extremely rare cases through the following:
- Oral sex. Oral sex carries little to no risk for getting or transmitting HIV. Things like oral ulcers, bleeding gums, genital sores, and the presence of other sexually transmitted infections (STIs) may increase the risk of HIV spreading through oral sex. However, the risk is still extremely low, and much lower than with anal or vaginal sex.
- Receiving blood transfusions, blood products, or organ/tissue transplants that are contaminated with HIV. There is rigorous testing of the U.S. blood supply and donated organs and tissues, so the associated risk is extremely low.
- Being bitten by a person living with HIV. There is no risk of transmission if the skin is not broken because HIV is not transmitted through saliva.
- Deep, open-mouth kissing if both partners have sores or bleeding gums and blood from the HIV-positive partner gets into the bloodstream of the HIV-negative partner.
- Eating food that has been pre-chewed by a person with HIV. The only known cases are among infants. You can’t get HIV by consuming food handled by someone with HIV.
How is HIV Not Spread?
HIV is not spread through:
- Sexual activities that don’t involve the exchange of body fluids, such as touching
- Casual contact, like shaking hands, hugging, or closed-mouth or “social” kissing (for example, a kiss on the cheek)
- Contact with surfaces or items, like door handles; shared food, drinks, drinking glasses, or utensils; drinking fountains; or toilet seats
- Air or water, including in swimming pools
- Insects or animals, including mosquitoes, ticks, and household animals or pets
- Mucus (including when coughing or sneezing), saliva, tears, sweat, feces, or urine
- Donating blood
HIV can’t be passed through healthy, unbroken skin.
How Does Viral Load Affect the Spread of HIV?
Viral load is the amount of HIV in the blood of someone who has HIV. If taken as prescribed, HIV medicine (called antiretroviral therapy or ART) can reduce a person’s HIV viral load to a very low level. This is called viral suppression. When the viral load becomes so low that a standard lab test can’t detect it, this is called having an undetectable viral load. Almost everyone who takes HIV medicine as prescribed can achieve an undetectable viral load, usually within 6 months after starting treatment.
People living with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load will not transmit HIV to their HIV-negative partners through sex. To keep an undetectable viral load, people living with HIV must take HIV medicine as prescribed and visit their health care provider regularly to get a viral load test.
How Do You Get AIDS?
You can’t “catch” AIDS (acquired immunodeficiency syndrome). AIDS is the most advanced stage of HIV infection. If a person has HIV and is not on HIV medicine, the virus will weaken the body’s immune system and the person will eventually progress to AIDS.
When HIV has progressed to AIDS, it badly damages a person’s immune system and they get a number of severe illnesses, called opportunistic infections.
However, thanks to today’s effective HIV treatment, most people living with HIV in the U.S. do not progress to AIDS. People living with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load can stay healthy and will not progress to AIDS.
People who are HIV-negative can prevent getting HIV by using pre-exposure prophylaxis (PrEP), medicine that can stop HIV from taking hold in the body. There is also post-exposure prophylaxis (PEP), a short course of HIV medicines taken very soon after a possible exposure to HIV to prevent the virus from taking hold in your body. PEP must be started within 72 hours of a possible exposure to be effective.