What is HIV?

HIVstands for human immunodeficiency virus. This is the virus that causes AIDS. HIV is different from most other viruses because it attacks the immune system. The immune system gives our bodies the ability to fight infections. HIV finds and destroys a type of white blood cell (T cells or CD4 cells) that the immune system must have to fight disease.

What is AIDS?

AIDS stands for acquired immunodeficiency syndrome. AIDS is the final stage of HIV infection. It can take years for a person infected with HIV, even without treatment, to reach this stage. Having AIDS means that the virus has weakened the immune system to the point at which the body has a difficult time fighting infections. When someone has one or more of these infections and a low number of T cells, he or she has AIDS.

How HIV Is or Is Not Transmitted?

HIV is a fragile virus. It cannot live for very long outside the body. As a result, the virus is not transmitted through day-to-day activities such as shaking hands, hugging, or a casual kiss. You cannot become infected from a toilet seat, drinking fountain, doorknob, dishes, drinking glasses, food, or pets. You also cannot get HIV from mosquitoes.  HIV is primarily found in the blood, semen, or vaginal fluid of an infected person. HIV is transmitted in 3 main ways:

• Having sex (anal, vaginal, or oral) with someone infected with HIV
• Sharing needles and syringes with someone infected with HIV
• Being exposed (fetus or infant) to HIV before or during birth or through breast feeding

HIV also can be transmitted through blood infected with HIV. However, since 1985, all donated blood in the United States has been tested for HIV. Therefore, the risk for HIV infection through the transfusion of blood or blood products is extremely low. The U.S. blood supply is considered among the safest in the world.
You may be at increased risk for infection if you have

• injected drugs or steroids, during which equipment (such as needles, syringes, cotton, water) and blood were shared with others
• had unprotected vaginal, anal, or oral sex (that is, sex without using condoms) with men who have sex with men, multiple partners, or anonymous partners
• exchanged sex for drugs or money

• been given a diagnosis of, or been treated for, hepatitis, tuberculosis (TB), or a sexually transmitted disease (STD) such as syphilis
• received a blood transfusion or clotting factor during 1978–1985

• had unprotected sex with someone who has any of the risk factors listed above

Symptoms of HIV Infection

The only way to know whether you are infected is to be tested for HIV. You cannot rely on symptoms alone because many people who are infected with HIV do not have symptoms for many years. Someone can look and feel healthy but can still be infected. In fact, one quarter of the HIV-infected persons in the United States do not know that they are infected.  Once HIV enters the body, the body starts to produce antibodies—substances the immune system creates after infection. Most HIV tests look for these antibodies rather than the virus itself. There are many different kinds of HIV tests, including rapid tests and home test kits. All HIV tests approved by the US government are very good at finding HIV.

Finding a Testing Site

Many places offer HIV testing: health departments, doctors' offices, hospitals, and sites specifically set up to provide HIV testing.  You can locate a testing site by visiting the CDC HIV testing database or by calling CDC-INFO (formerly the CDC National AIDS Hotline) at 1-800-CDC-INFO (1-800-232-4636) 24 Hours/Day.  You do not have to give any personal information about yourself to use these services to find a testing site.