What Is AIDS?
July 27, 2012
AIDS stands for Acquired Immune Deficiency Syndrome:
AIDS is caused by a virus called HIV, the Human Immunodeficiency Virus. If you get infected with HIV, your body will try to fight the infection. It will make "antibodies" -- special molecules to fight HIV.
Tests for HIV look for these antibodies in your blood or mouth lining. If you have them in your blood, it means that you have HIV infection. People who have the HIV antibodies are called "HIV-Positive." Fact Sheet 102 has more information on HIV testing.
Being HIV-positive, or having HIV disease, is not the same as having AIDS. Many people are HIV-positive but don't get sick for many years. As HIV disease continues, it slowly wears down the immune system. Viruses, parasites, fungi and bacteria that usually don't cause any problems can make you very sick if your immune system is damaged. These are called "opportunistic infections." See Fact Sheet 500 for an overview of opportunistic infections.
You don't actually "get" AIDS. You might get infected with HIV, and later you might develop AIDS. You can get infected with HIV from anyone who's infected, even if they don't look sick and even if they haven't tested HIV-positive yet. The blood, vaginal fluid, semen, and breast milk of people infected with HIV has enough of the virus in it to infect other people. Most people get the HIV virus by:
Getting a transfusion of infected blood used to be a way people got AIDS, but now the blood supply is screened very carefully and the risk is extremely low.
There are no documented cases of HIV being transmitted by tears or saliva, but it is possible to be infected with HIV through oral sex or in rare cases through deep kissing, especially if you have open sores in your mouth or bleeding gums. For more information, see the following Fact Sheets:
The Centers for Disease Control and Prevention (CDC) estimates that 1 million to 1.2 million U.S. residents are living with HIV infection or AIDS; about a quarter of them do not know they have it. About 73 percent of the 56,000 new infections each year are in men, and about 27 percent in women. About half of the new infections are in Blacks, even though they make up only 12 percent of the US population. In the mid-1990s, AIDS was a leading cause of death. However, newer treatments have cut the AIDS death rate significantly. For more information, see the U.S. Government fact sheet at www.cdc.gov/hiv/topics/surveillance/index.htm.
You might not know if you get infected by HIV. Within a few weeks after being infected, some people get fever, headache, sore muscles and joints, stomach ache, swollen lymph glands, or a skin rash for one or two weeks. Most people think it's the flu. Some people have no symptoms. Fact Sheet 103 has more information on the early stage of HIV infection.
The virus will multiply in your body for a few weeks or even months before your immune system responds. During this time, you won't test positive for HIV, but you can infect other people.
When your immune system responds, it starts to make antibodies. When this happens, you will test positive for HIV. After the first flu-like symptoms, some people with HIV stay healthy for ten years or longer. But during this time, HIV is damaging your immune system.
One way to measure the damage to your immune system is to count your CD4+ cells. These cells, also called "T-helper" cells, are an important part of the immune system. Healthy people have between 500 and 1,500 CD4 cells in a milliliter of blood. Fact Sheet 124 has more information on CD4 cells.
Without treatment, your CD4 cell count will most likely go down. You might start having signs of HIV disease like fevers, night sweats, diarrhea, or swollen lymph nodes. If you have HIV disease, these problems will last more than a few days, and probably continue for several weeks.
HIV disease becomes AIDS when your immune system is seriously damaged. If you have less than 200 CD4+ cells or if your CD4 percentage is less than 14%, you have AIDS. See Fact Sheet 124 for more information on CD4 cells. If you get an opportunistic infection, you have AIDS. There is an "official" list of opportunistic infections, put out by the Centers for Disease Control (CDC). The most common ones are:
AIDS-related symptoms also include serious weight loss, brain tumors, and other health problems. Without treatment, these opportunistic infections can kill you. The official (technical) CDC definition of AIDS is available at www.thebody.com/content/art14002.html.
AIDS is different in every infected person. A few people may die in a few months after getting infected, but most live fairly normal lives for many years, even after they "officially" have AIDS. A few HIV-positive people stay healthy for many years even without taking antiretroviral medications (ART).
There is currently no cure for AIDS (see Fact Sheet 485.) Antiretroviral therapy (ART, see Fact Sheet 403)can slow down the HIV virus, and slow down the damage to your immune system. Most people stay healthy as long as they continue ART. There is no way to "clear" HIV from the body.
Other drugs can prevent or treat opportunistic infections (OIs). In most cases, these drugs work very well. The newer, stronger ARVs have also helped reduce the rates of most OIs. A few OIs, however, are still very difficult to treat. See Fact Sheet 500 for more information on opportunistic infections.
More detailed information on AIDS can be found at MedLine Plus at www.nlm.nih.gov/medlineplus/aids.html.
This article was provided by AIDS InfoNet. Visit AIDS InfoNet's website to find out more about their activities and publications.