Human immunodeficiency virus (HIV) is the virus that causes acquired immune deficiency syndrome (AIDS) and is transmitted through contact with infected blood and bodily fluids. Such contact can occur through unprotected sex, through sharing of needles or other drug injection equipment, through mother-to-child transmission during pregnancy or breast-feeding, and through receipt of infected blood transfusions and plasma products during medical care in some parts of the world. There is currently no cure for HIV/AIDS. Once an individual contracts HIV, he or she has it for life.
HIV infects immune cells in the body called CD4 positive (CD4+) T cells, which are essential for fighting infections. HIV converts these cells into “factories” that produce more of the HIV virus to infect other healthy cells, eventually destroying the CD4+ cells. An infected person may look and feel fine for many years and may not even be aware of the infection. However, as the individual loses CD4+ cells and the immune system weakens, he or she becomes more vulnerable to illnesses and other infections. Physicians make an AIDS diagnosis when a patient has one or more of these illnesses and a CD4+ cell count of less than 200. Treatment for HIV typically involves highly active antiretroviral therapy, better known as HAART.