HIV, or human immunodeficiency virus, is the virus that causes AIDS (Acquired Immune Deficiency Syndrome). HIV kills or damages cells of the body's immune system (particularly cells called CD4-positive [CD4+] T cells, or T helper cells, which is a type of white cell vital to fighting infection). This destroys the body's ability to fight infections and certain cancers. 

The most advanced stages of HIV infection are known as AIDS. HIV can be transmitted through sexual contact, contaminated needles or syringes, contaminated blood products, and transmission from mother to child during pregnancy, the birth process, or breast milk.

The NICHD is one of many federal agencies and NIH Institutes working to understand HIV/AIDS. Unlike other Institutes and agencies, the NICHD's research focuses on the biology, prevention, and treatment of HIV/AIDS in women (including pregnant women), infants, children, and adolescents.

Another Institute—the National Institute of Allergy and Infectious Diseases (NIAID)—leads HIV/AIDS research at the NIH and conducts and supports research on more general aspects of the disease. Information provided in the Condition Information section of this website is specific to the populations that the NICHD studies; links to more general HIV/AIDS information from the NIAID are also provided.

Common Name

  • HIV
  • AIDS
  • SIDA in Spanish

Medical or Scientific Name

  • Human Immunodeficiency Virus
  • Acquired Immune Deficiency Syndrome
Alternate Titles
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