HIV, or human immunodeficiency virus, affects specific cells of the immune system, called CD4 cells, or T cells. When untreated, over time, HIV can destroy so many of these cells that the body can’t fight off infections and disease. When this happens, HIV infection leads to AIDS, acquired immunodeficiency syndrome.

Unlike some other viruses, the human body cannot get rid of HIV. That means that once you have HIV, you have it for life. There is no cure for HIV, however, with proper medical care, HIV can be controlled. An individual diagnosed with HIV and treated before the disease is far advanced can have a nearly normal life expectancy.

Main Modes of Transmission

In the United States, HIV is spread mainly by having sex without a condom (especially anal and vaginal sex) and sharing needles, syringes, rinse water, or other equipment (works) used to prepare injection drugs with someone who is HIV positive.

Although it’s less common, HIV can also be spread by being born to a mother living with HIV, known as perinatal transmission. HIV can be passed from mother to child during pregnancy, birth, or breastfeeding. Pre-chewing of food for infants is also a transmission risk.

Having a sexually transmitted infection (STI) can increase the risk of getting or transmitting HIV. If you are HIV-negative but have an STI, you are at least 2 to 5 times as likely to get HIV if you have condomless sex with someone who is HIV-positive.

More about HIV transmission.

HIV Testing and Prevention

The only way to know if you are infected with HIV is to be tested. Many people who are infected with HIV do not have any symptoms at all for 10 years or more. Some people who are infected with HIV report having flu-like symptoms but the only way to know is to be tested.

It’s important to have ongoing and open discussions with your partners about HIV testing and risk behaviors. Talking openly about HIV can reduce the stigma that keeps too many from seeking testing, prevention and treatment services, and the support they need.

Find an HIV testing site or ask your health care provider to give you an HIV test.

More about HIV prevention.

HIV in the United States

  • HIV incidence in the United States has been stable around 50,000 people each year since the 1990s.
  • The most recent data from 2010 reports about 1.1 million people living with HIV in the United States including an estimated 176,000 people who do not know they are have the virus.
  • About 15,500 people died with AIDS in 2010.
  • Most cases of HIV occur in metropolitan areas.
  • In 2010, blacks accounted for the largest proportion of AIDS diagnoses in the South, the Northeast, and the Midwest.
  • In 2010, 162 children were perinatally infected with HIV, meaning during pregnancy, birth, or through breastfeeding.
  • From the beginning of the epidemic through 2009, an estimated 4,986 people diagnosed with AIDS were infected perinatally.

Find more statistics, research, recommendations, and resources on HIV in the United States at

Information provided by US Centers for Disease Control and Prevention (CDC),