HIV/AIDS 101

HIV (Human Immunodeficiency Virus) is a virus that attacks and weakens the body's defense (immune) system until it can no longer fight off illnesses. HIV targets and kills white blood (CD4 /T) cells, which direct your body's immune system to defend against infection.

AIDS (Acquired Immunodeficiency Syndrome) 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., an HIV-infected person receives a diagnosis of AIDS when his/her CD4 count reaches less than 200 cells per cubic millimeter of blood (200 cells/mm³) or if diagnosed with a specific illness. An average CD4 cell count in a healthy person is 1,150 mm³. A person diagnosed with AIDS would also likely have a high viral load (quantity of HIV). Having HIV does not mean a person has AIDS.

HIV can be transmitted through the exchange of body fluids from people living with HIV, including blood, breast milk, semen, and vaginal secretions. HIV can also be transmitted to a child during pregnancy and delivery.

People living with HIV who are taking ART (antiretroviral treatment) and have an undetectable viral load will not transmit HIV to their sexual partners. Early access to ART and support to remain on treatment is therefore critical not only to improve the health of people living with HIV but also to prevent HIV transmission.

HIV can also be transmitted through needles contaminated with HIV-infected blood; sharing injection drug equipment, including needles used for injecting drugs, tattooing, or body piercing.

People cannot become infected with HIV through ordinary day-to-day contact such as kissing, hugging, shaking hands, or sharing personal objects, food, or water.

Watch "What HIV Does Inside the Body" for a short, informative explanation of how HIV attacks and affects your health.

The safest way to avoid HIV infection is to not have sexual intercourse, oral sex, or share needles or injection equipment with an HIV-positive person. The risk of HIV infection is reduced within a relationship in which both partners are monogamous and have been free of HIV for six months. If there is any doubt about the risk of infection, always use a latex barrier when having sex of any kind - vaginal, oral, or anal.

When used as recommended, PrEP (Pre-Exposure Prophylaxis), a daily medication (pills or injections) for HIV-negative people at high risk, drastically reduces their chance of getting HIV from sex or injection drug use.

Knowing you are HIV-positive will allow you to seek early treatment that could help you stay healthy longer. Whether you are HIV-negative or HIV-positive, you can learn how to prevent future infection with HIV or other STDs through counseling at many testing centers.

Undetectable means that there is so little HIV in your blood that it can't be measured by a test. Watch "The Goal of Undetectable" to see how you can protect your health and the people you care about.