HIV is a virus spread through certain body fluids that attacks the body’s immune system, specifically the CD4 cells, often called T cells. Over time, HIV can destroy so many of these cells that the body can’t fight off infections and disease. These special cells help the immune system fight off infections. Untreated, HIV reduces the number of CD4 cells (T cells) in the body. This damage to the immune system makes it harder and harder for the body to fight off infections and some other diseases. Opportunistic infections or cancers take advantage of a very weak immune system and signal that the person has AIDS. Learn more about the stages of HIV and how to know whether you’re infected.

What Is HIV?

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HIV stands for human immunodeficiency virus. 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. 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 medicine used to treat HIV is called antiretroviral therapy or ART. If taken the right way, every day, this medicine can dramatically prolong the lives of many people infected with HIV, keep them healthy, and greatly lower their chance of infecting others. 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.

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What Is AIDS?

AIDS is the most severe phase of HIV infection. People with AIDS have such badly damaged immune systems that they get an increasing number of severe illnesses, called opportunistic infections.

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What Are the Stages of HIV Infection?

Without treatment, HIV advances in stages, overwhelming your immune system and getting worse over time. The three stages of HIV infection are: (1) acute HIV infection, (2) clinical latency, and (3) AIDS (acquired mmunodeficiency syndrome).However, there’s good news: by using HIV medicines (called antiretroviral therapy or ART) consistently, you can prevent HIV from progressing to AIDS. ART helps control the virus so that you can live a longer, healthier life and greatly reduces the risk of transmitting HIV to others.
 

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How is HIV transmitted?

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​HIV is spread only in certain body fluids from a person who has HIV. These fluids are blood, semen, pre-seminal fluids, rectal fluids, vaginal fluids, and breast milk. In the world, HIV is spread mainly by having sex or sharing injection drug equipment, such as needles, with someone who has HIV.

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What are the prevention tools?

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• Get tested and know your partner’s HIV status. Talk to your partner about HIV testing and get tested before you have 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.

• Use condoms. Use a condom correctly every time you have sex. Read this fact sheet from CDC on how to use condoms correctly.

• Limit your number of sexual partners. The more partners you have, the more likely you are to have a partner with poorly controlled HIV or to have a partner with a sexually transmitted disease (STD). Both of these factors can increase the risk of HIV transmission.

• Get tested and treated for STDs. Insist that your partners get tested and treated, too. Having an STD can increase your risk of becoming infected with HIV or spreading it to others.

• Talk to your health care provider about pre-exposure prophylaxis (PrEP). PrEP is an HIV prevention option for people who don't have HIV but who are at high risk of becoming infected with HIV. PrEP involves taking a specific HIV medicine every day. For more information, read the AIDSinfo fact sheet on Pre-Exposure Prophylaxis (PrEP).

• Don't inject drugs. But if you do, use only sterile drug injection equipment and water and never share your equipment with others.