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It is the virus that can lead to acquired immunodeficiency syndrome or AIDS if not treated. Unlike some other viruses, the human body can’t get rid of HIV completely, even with treatment. So once you get HIV, you have it for life.

HIV attacks the body’s immune system, specifically the CD4 cells (T cells), which help the immune system fight off infections. If untreated, HIV reduces the number of CD4 cells (T cells) in the body, making the person more likely to get other infections or infection-related cancers. Over time, HIV can destroy so many of these cells that the body can’t fight off infections and disease. These opportunistic infections or cancers take advantage of a very weak immune system and signal that the person has AIDS, the last stage of HIV infection.

No effective cure currently exists, but with proper medical care, HIV can be controlled. The therapy used to treat HIV is called antiretroviral therapy or ART. If people with HIV take ART as prescribed, their viral load (amount of HIV in their blood) can become undetectable. If it stays undetectable, they can live long, healthy lives and have no risk of transmitting HIV to an HIV-negative partner through sex. Before the introduction of ART in the mid-1990s, people with HIV could progress to AIDS in just a few years. Today, someone diagnosed with HIV and treated before the disease is far advanced can live nearly as long as someone who does not have HIV.

Only certain body fluids-blood, semen (cum), pre-seminal fluid (pre-cum), rectal fluids, vaginal fluids, and breast milk-from a person who has HIV can transmit HIV. These fluids must come in contact with a mucous membrane or damaged tissue or be directly injected into the bloodstream (from a needle or syringe) for transmission to occur. Mucous membranes are found inside the rectum, vagina, penis, and mouth.

  • HIV is spread mainly by

    Having anal or vaginal sex with someone who has HIV without using a condom or taking medicines to prevent or treat HIV.

    For the HIV-negative partner, receptive anal sex (bottoming) is the highest-risk sexual behavior, but you can also get HIV from insertive anal sex (topping).

    Either partner can get HIV through vaginal sex, though it is less risky for getting HIV than receptive anal sex.

    Sharing needles or syringes, rinse water, or other equipment (works) used to prepare drugs for injection with someone who has HIV. HIV can live in a used needle up to 42 days depending on temperature and other factors.

  • Less commonly, HIV may be spread

    From mother to child during pregnancy, at birth, or during breastfeeding. Although the risk can be higher if a mother is living with HIV and not taking medicine, recommendations to test all pregnant women for HIV and start HIV treatment immediately have lowered the number of babies who are born with HIV.

    By being stuck with an HIV-contaminated needle or other sharp object. This is a risk mainly for health care workers.

  • How long does HIV survive outside the body?

    HIV does not survive for a long time outside the human body (such as on surfaces), and it cannot reproduce itself outside a human host. It is not spread by

    • Mosquitoes, ticks, or other insects.
    • Saliva, tears, or sweat that is not mixed with the blood of an HIV-positive person.
    • Hugging, shaking hands, sharing toilets, sharing dishes, or closed-mouth or "social" kissing with someone who is HIV-positive.
    • Other sexual activities that don’t involve the exchange of body fluids (for example, touching).
  • How can I prevent getting HIV from sex?

    Use condoms the right way every time you have sex, take medicines to prevent or treat HIV if appropriate, choose less risky sexual behaviors, get tested for other sexually transmitted infections (STIs), and limit your number of sex partners. The more of these actions you take, the safer you can be.

    Specifically, you can

    Use condoms the right way every time you have sex.

    Reduce your number of sexual partners. This can lower your chances of having a sexual partner who will transmit HIV to you. The more partners you have, the more likely you are to have a partner with HIV whose viral load is not suppressed or to have a sexual partner with a sexually transmitted disease. Both of these factors can increase the risk of HIV transmission.

    Use pre-exposure prophylaxis (PrEP), taking HIV medicines daily to prevent HIV infection, if you are at very high risk for HIV. PrEP should be considered if you are HIV-negative and in an ongoing sexual relationship with an HIV-positive partner. PrEP also should be considered if you aren’t in a mutually monogamous relationship with a partner who recently tested HIV-negative, and you are a:

    • gay or bisexual man who has had anal sex without a condom or been diagnosed with an STI in the past 6 months;
    • man who has sex with both men and women;
    • heterosexual man or woman who does not regularly use condoms during sex with partners of unknown HIV status who are at very high risk of HIV infection (for example, people who inject drugs or women who have bisexual male partners).

    Post-exposure prophylaxis (PEP) means taking HIV medicines after being potentially exposed to HIV to prevent becoming infected. If you’re HIV-negative or don’t know your HIV status and think you have recently been exposed to HIV during sex (for example, if the condom breaks). The sooner you start PEP, the better; every hour counts. If you’re prescribed PEP, you’ll need to take it once or twice daily for 28 days. Keep in mind that your chance of getting HIV is null if your HIV-positive partner is taking medicine to treat HIV infection (called antiretroviral therapy, or ART) as prescribed and his or her viral load stays undetectable for more of six months.

    If you’re HIV-negative and your partner is HIV-positive, encourage your partner to get and stay on treatment. If taken as prescribed, HIV medicine (ART) can ma—ke the amount of HIV in the blood (viral load) very low-so low that a test can’t detect it (called an undetectable viral load). People with HIV who get and keep an undetectable viral load can stay healthy for many years and have effectively no risk of transmitting HIV to an HIV-negative partner through sex.

    Choose less risky sexual behaviors. HIV is mainly spread by having anal or vaginal sex without a condom or without taking medicines to prevent or treat HIV.

    Receptive anal sex is the riskiest type of sex for getting HIV. It’s possible for either partner-the partner inserting the penis in the anus (the top) or the partner receiving the penis (the bottom)-to get HIV, but it is much riskier for an HIV-negative partner to be the receptive partner. That’s because the lining of the rectum is thin and may allow HIV to enter the body during anal sex.

    Vaginal sex also carries a risk for getting HIV, though it is less risky than receptive anal sex. Most women who get HIV get it from vaginal sex, but men can also get HIV from vaginal sex.

    In general, there is little to no risk of getting or transmitting HIV from oral sex. Theoretically, transmission of HIV is possible if an HIV-positive man ejaculates in his partner’s mouth during oral sex. However, the risk is still very low, and much lower than with anal or vaginal sex. Factors that may increase the risk of transmitting HIV through oral sex are oral ulcers, bleeding gums, genital sores, and the presence of other STIs, which may or may not be visible.

    Sexual activities that don’t involve contact with body fluids (semen, vaginal fluid, or blood) carry no risk of HIV transmission but may pose a risk for other STIs.

  • Should I get tested for HIV ?

    If you never tested for HIV or if you were HIV-negative the last time you were tested, and that test was more than one year ago, and you answer yes to any of the following questions, you should get an HIV test as soon as possible because these things increase your chances of getting the virus:

    • Have you had unprotected - sex—anal or vaginal?
    • Have you had more than one sex partner since your last HIV test?
    • Have you injected drugs and shared needles or works (for example, water or cotton) with others?
    • Have you had sex under the effect of alcohol or drugs which might alter your judgment?
    • Have you been diagnosed with or sought treatment for another sexually transmitted disease?
    • Have you been diagnosed with or treated for hepatitis or tuberculosis (TB)?
    • Have you had sex with someone who could answer yes to any of the above questions or someone whose sexual history you don’t know?

    You should be tested at least once a year if you keep doing any of these things. Sexually active gay and bisexual men may benefit from more frequent testing (for example, every 3 to 6 months).

    Before having sex for the first time with a new partner, you and your partner should talk about your sexual and drug-use history, disclose your HIV status, and consider getting tested for HIV and learning the results.

  • What is HIV stigma?

    HIV stigma is negative attitudes and beliefs about people living with HIV. It is the prejudice that comes with labeling an individual as part of a group that is believed to be socially unacceptable.

    Here are a few examples:

    • Believing that only certain groups of people can get HIV
    • Giving moral judgments about people who take steps to prevent HIV transmission
    • Feeling that people deserve to get HIV because of their choices

    HIV stigma and discrimination affect the emotional well-being and mental health of people living with HIV. People living with HIV often internalize the stigma they experience and begin to develop a negative self-image. They may fear they will be discriminated against or judged negatively if their HIV status is revealed.

    "Internalized stigma" or "self-stigma" happens when a person takes in the negative ideas and stereotypes about people living with HIV and start to apply them to themselves. HIV internalized stigma can lead to feelings of shame, fear of disclosure, isolation, and despair. These feelings can keep people from getting tested and treated for HIV.