HIV infection is a disease caused by the human immunodeficiency virus (HIV). The condition gradually destroys the immune system, which makes it harder for the body to fight infections.

This article provides a general overview. For more detailed information, see:

• AIDS
• Acute HIV infection
• Asymptomatic HIV infection
• Early symptomatic HIV infection

Human immunodeficiency virus infection

The human immunodeficiency virus (HIV) can be spread by the following:

• Contaminated blood transfusions and blood products
• Intimate sexual contact
• The use of contaminated needles and syringes

The virus may also spread from a mother to her baby, either at birth or through breastfeeding.

People who become infected with HIV may have no symptoms for up to 10 years, but they can still pass the infection to others. After being exposed to the virus, it usually takes about 3 months for the HIV ELISA blood test to change from HIV negative to HIV positive.

HIV has spread throughout the US. The disease is more prevalent in urban areas, especially in inner cities.

Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007: sect XXIV.