HIV Transmission: How HIV Spreads

By Ashley Henshaw. Medically reviewed by Tom Iarocci, MD. May 7th 2016

The human immunodeficiency virus (HIV) is an extremely dangerous virus that attacks a person’s body by destroying blood cells that are needed to help fight off disease. It’s estimated that over 50,000 people contract HIV each year, according to the Centers for Disease Control and Prevention (CDC).

HIV is transmitted from one person to another through bodily fluids. The fluids that carry HIV — blood, semen, pre-ejaculatory fluid, vaginal secretions, rectal fluids, and breast milk — must come into contact with a damaged tissue or mucous membrane of another person in order for the virus to be spread. Most commonly, this occurs in one of two ways: through sexual contact, or when an infected bodily fluid is directly injected into the blood stream of another person with a needle or syringe.

In the United States specifically, HIV most often spreads by one or more of the following:

  • Sexual contact: Having sex with someone with HIV without using a condom is the most common form of HIV transmission. Unprotected anal sex has a higher risk of transmission than unprotected vaginal sex.
  • STDsThough HIV itself is considered a sexually transmitted disease, having other STDs can increase the risk of infection during sex.
  • Multiple sex partners: Having multiple sexual partners increases the risk of HIV transmission.
  • Mother to child: HIV can be transmitted from a mother to a child during pregnancy, birth or breastfeeding.
  • Drug use: Needles, syringes, rinse water and other equipment used to prepare illicit drugs for injection is another common method of HIV transmission.

Less Common Modes of HIV Transmission

Other modes of HIV transmission are not as common as those listed above, but are nonetheless important to be aware of, including:

  • Oral sex is not without risk: Unprotected oral sex is another form of sexual contact through which HIV can be spread, though it contains a much lower risk compared to vaginal or anal sex.
  • Needle stick: Being pricked by an HIV-contaminated needle or other sharp object could transmit the virus. This is primarily a concern for health care workers.
  • Broken skin: When broken skin, a wound or a mucous membrane comes into contact with HIV-infected blood or bodily fluids, the virus could be transmitted.Tattoos and piercings: Getting a tattoo or piercing with an HIV-infected needle or instrument could transmit the virus.
  • Deep kissing: Open-mouth or French kissing could cause HIV transmission if the infected person has a cut in his or her mouth, allowing blood to pass to the other person. However, this sequence of events is extremely rare.
  • Eating pre-chewed food: HIV can be transmitted by eating food that has been pre-chewed by a person with the virus. There has to be blood present in the food for this to occur – it has only been documented in rare cases with infants receiving pre-chewed food from caregivers.
  • Blood transfusions: HIV can be transmitted via blood transfusions or organ and tissue transplants which are contaminated with the virus. Fortunately, today in the U.S. this is extremely rare as there are rigorous testing procedures in place.

How HIV Is Not Spread

There are plenty of myths out there about HIV, and many of them have to do with the ways that HIV can be transmitted. The following are some of the ways that HIV cannot be spread:

  • Air
  • Water
  • Bites or stings from insects
  • Saliva, tears or sweat
  • Casual contact (like shaking hands or hugging)
  • Closed mouth or “social” kissing

Next Steps

Refraining from sexual activity or being in a long-term and mutually monogamous relationship with an uninfected partner are the two most reliable ways to avoid transmission, according to the CDC.

Many people with STDs, including HIV, are not aware of their status, however. There are several key components to preventing the spread of HIV, including the following:

  • Know your status: The CDC recommends that everyone between the ages of 13 and 64 get tested for HIV at least once. If you engage in any of the activities mentioned in the first section of this article (e.g., unprotected sex, having multiple sex partners, sharing needles, etc.), it’s important to get tested for HIV at least once a year. Experts recommend testing for all pregnant women, since transmission to the baby is largely preventable through antiretroviral therapy. Women who plan on getting pregnant may also want to get tested.
  • Get treatment: If you do find out that you are HIV-positive, you need to seek medical treatment as soon as possible. Medications and supportive services can help you stay healthy and learn about steps you can take to reduce the risk of transmission to others.
  • Always use protection: Latex condoms are very effective at reducing the risk of transmission of HIV, but proper use — during each and every instance of sexual activity — is required.
  • Get educated: There are many risk reduction programs in which you can participate to learn more about how to use a condom properly, how to get tested and other important facts about preventing HIV transmission.
  • Prevent STDs: By getting tested and treated for other STDs, you reduce your risk of being infected with HIV.
  • Avoid having multiple partners: The more sexual partners you have, the higher your risk for being infected with HIV or another STD. Encourage partners to get tested for HIV and other STDs before engaging in sexual activity.
  • Don’t share needles: Only use a sterile, unused needle for intravenous drugs, steroids or any injectable medications.
  • Circumcision: Male circumcision reduces the risk of HIV transmission from an infected woman to a man during vaginal sex.

HIV is a very harmful and debilitating virus that can eventually lead to AIDS. It is vital that you understand the risks of HIV transmission and take steps to prevent it. Ask your doctor if you have more questions about preventing HIV or if you want to get tested for the virus.

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