What is HIV?

HIV (Human Immunodeficiency Virus) is the virus that causes AIDS. This virus is passed from one person to another through blood-to-blood and sexual contact. In addition, infected pregnant women can pass HIV to their baby during pregnancy or delivery, as well as through breast-feeding. People with HIV have what is called HIV infection. Most of these people will develop AIDS as a result of their HIV infection. 

What is AIDS?

AIDS (Acquired Immune Deficiency Syndrome) is the final stage of HIV infection. When the immune system cell drop to a very low level, a person's ability to fight infection is lost. In addition, there are several conditions that occur in people with HIV infection with this degree of immune system failure — these are called AIDS defining illnesses. 

How does HIV and AIDS cause illness?

HIV attacks and destroys a type of white blood cell called a CD4 cell. This cell's main function is to fight disease. When a person's CD4 cell count gets low, they are more susceptible to illnesses.