What Are HIV and AIDS?

Content From: HIV.govUpdated: June 15, 20223 min read

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Human Immunodeficiency Virus (HIV) is a virus that attacks cells that help the body fight infection. There's no cure, but it is treatable with medicine.

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. It is spread by contact with certain bodily fluids of a person with HIV, most commonly during unprotected sex (sex without a condom or HIV medicine to prevent or treat HIV), or through sharing injection drug equipment.

If left untreated, HIV can lead to the disease AIDS (acquired immunodeficiency syndrome).

The human body can’t get rid of HIV and no effective HIV cure exists. So, once you have HIV, you have it for life.

Luckily, however, effective treatment with HIV medicine (called antiretroviral therapy or ART) is available. If taken as prescribed, HIV medicine can reduce the amount of HIV in the blood (also called the viral load) to a very low level. This is called viral suppression. If a person’s viral load is so low that a standard lab can’t detect it, this is called having an undetectable viral load. People with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load can live long and healthy lives and will not transmit HIV to their HIV-negative partners through sex.

In addition, there are effective methods to prevent getting HIV through sex or drug use, including pre-exposure prophylaxis (PrEP), medicine people at risk for HIV take to prevent getting HIV from sex or injection drug use, and post-exposure prophylaxis (PEP), HIV medicine taken within 72 hours after a possible exposure to prevent the virus from taking hold. Learn about other ways to prevent getting or transmitting HIV.

What Is AIDS?

AIDS is the late stage of HIV infection that occurs when the body’s immune system is badly damaged because of the virus.

In the U.S., most people with HIV do not develop AIDS because taking HIV medicine as prescribed stops the progression of the disease.

A person with HIV is considered to have progressed to AIDS when:

  • the number of their CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3). (In someone with a healthy immune system, CD4 counts are between 500 and 1,600 cells/mm3.) OR
  • they develop one or more opportunistic infections regardless of their CD4 count.

Without HIV medicine, people with AIDS typically survive about 3 years. Once someone has a dangerous opportunistic illness, life expectancy without treatment falls to about 1 year. HIV medicine can still help people at this stage of HIV infection, and it can even be lifesaving. But people who start HIV medicine soon after they get HIV experience more benefits—that’s why HIV testing is so important.

How Do I Know If I Have HIV?

The only way to know for sure if you have HIV is to get tested. Testing is relatively simple. You can ask your health care provider for an HIV test. Many medical clinics, substance abuse programs, community health centers, and hospitals offer them too.

To find an HIV testing location near you, use the HIV Services Locator.

HIV self-testing is also an option. Self-testing allows people to take an HIV test and find out their result in their own home or other private location. You can buy a self-test kit at a pharmacy or online. Some health departments or community-based organizations also provide self-test kits for a reduced cost or for free.

Learn more about HIV self-testing and which test might be right for you.

The COVID-19 pandemic has made it more difficult for some people to access traditional places where HIV testing is provided. Self-testing allows people to get tested for HIV while still following social distancing practices. Ask your local health department or HIV service organization if they offer self-testing kits.