OK—now to the scientific stuff.
First the basics: what is AIDS? AIDS (acquired immune deficiency syndrome) is a condition caused by a virus called HIV. This virus attacks the immune system, the body's "security force" that fights off infections. When the immune system breaks down, you lose this protection and can develop many serious, often deadly infections and cancers. These are called "opportunistic infections (OIs)" because they take advantage of the body's weakened defenses. You have heard it said that someone "died of AIDS." This is not entirely accurate, since it is the opportunistic infections that cause death. AIDS is the condition that lets the OIs take hold.
And what is HIV? HIV is a virus, like the flu or cold. A virus is really nothing but a set of instructions for making new viruses, wrapped up in some fat, protein and sugar. Without living cells, a virus can't do anything—it's like a brain with no body. In order to make more viruses (and to do all of the other nasty things that viruses do), a virus has to infect a cell. HIV mostly infects CD4 cells, also known as T cells, or T-helper cells. These are white blood cells that coordinate the immune system to fight disease, much like the quarterback of a football team. Once inside the cell, HIV starts producing millions of little viruses, which eventually kill the cell and then go out to infect other cells. All of the drugs marketed to treat HIV work by interfering with this process. There, that wasn't so hard, was it?
To learn more on how HIV infects a CD4 cell and begins to create more viruses, click on the following lesson link:
How is HIV transmitted? Are you infected? If you have visited this site looking for information about HIV because you think you might be infected—but you haven't tested for it yet, or have doubts about the tests—then you should read the following lessons: