What is AIDS?
AIDS stands for Acquired Immunodeficiency Syndrome.
Acquired - means that the disease is not hereditary but develops after birth from contact with a disease causing agent (in this case, HIV).
Immunodeficiency - means that the disease is characterized by a weakening of the immune system.
Syndrome - refers to a group of symptoms that collectively indicate or characterize a disease. In the case of AIDS this can include the development of certain infections and/or cancers, as well as a decrease in the number of certain cells in a person's immune system.
A diagnosis of AIDS is made by a physician using specific clinical or laboratory standards.
First the basics: 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 T-cells, also known as CD4+ cells, or T-helper cells. These cells...