What is HIV?

HIV (human immunodeficiency virus) is the virus that causes AIDS. This virus may be passed from one person to another when infected blood, semen, or vaginal secretions come in contact with an uninfected person's broken skin or mucous membranes*. 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. Some of these people will develop AIDS as a result of their HIV infection.

How can I get HIV?

You can get HIV...

by having unprotected sex- sex without a condom- with someone who has HIV. The virus can be in an infected person's blood, semen, or vaginal secretions and can enter your body through tiny cuts or sores in your skin, or in the lining of your vagina, penis, rectum, or mouth
by sharing a syringe to inject drugs or sharing drug equipment used to prepare drugs for injection with someone who has HIV.
from a blood transfusion or blood clotting factor that you got before 1985. (But today it is unlikely you could get infected that way because all blood in the United States has been tested for HIV since 1985.)

Babies born to women with HIV also can become infected during pregnancy, birth, or breast-feeding.

You cannot get HIV...

by working with or being around someone who has HIV
from sweat, spit, tears, clothes, drinking fountains, phones, toilet seats, or through everyday things like sharing a meal
from insect bites or stings
from donating blood
from a closed-mouth kiss (but there is a very small chance of getting it from open-mouthed or "French" kissing with an infected person because of possible blood contact).

Where did HIV come from?

The earliest known case of HIV-1 in a human was from a blood sample collected in 1959 from a man in Kinshasa, Democratic Republic of Congo. (How he became infected is not known.) Genetic analysis of this blood sample suggested that HIV-1 may have stemmed from a single virus in the late 1940s or early 1950s.

We know that the virus has existed in the United States since at least the mid- to late 1970s. From 1979-1981 rare types of pneumonia, cancer, and other illnesses were being reported by doctors in Los Angeles and New York among a number of male patients who had sex with other men. These were conditions not usually found in people with healthy immune systems.

In 1982 public health officials began to use the term "acquired immunodeficiency syndrome," or AIDS, to describe the occurrences of opportunistic infections, Kaposi's sarcoma (a kind of cancer), and Pneumocystis carinii pneumonia in previously healthy people. Formal tracking (surveillance) of AIDS cases began that year in the United States. In 1983, scientists discovered the virus that causes AIDS. The virus was at first named HTLV-III/LAV (human T-cell lymphotropic virus-type III/lymphadenopathy- associated virus) by an international scientific committee. This name was later changed to HIV (human immunodeficiency virus).

For many years scientists theorized as to the origins of HIV and how it appeared in the human population, most believing that HIV originated in other primates. Then in 1999, an international team of researchers reported that they had discovered the origins of HIV-1, the predominant strain of HIV in the developed world. A subspecies of chimpanzees native to west equatorial Africa had been identified as the original source of the virus. The researchers believe that HIV-1 was introduced into the human population when hunters became exposed to infected blood.

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 personÕs immune system.

How does HIV cause AIDS?

HIV destroys a certain kind of blood cell (CD4+ T cells) which is crucial to the normal function of the human immune system. In fact, loss of these cells in people with HIV is an extremely powerful predictor of the development of AIDS. Studies of thousands of people have revealed that most people infected with HIV carry the virus for years before enough damage is done to the immune system for AIDS to develop. However, sensitive tests have shown a strong connection between the amount of HIV in the blood and the decline in CD4+ T cells and the development of AIDS. Reducing the amount of virus in the body with anti-retroviral therapies can dramatically slow the destruction of a personÕs immune system.

How can I tell if I'm infected with HIV?

The only way to know if you are infected is to be tested for HIV infection. You cannot rely on symptoms to know whether or not you are infected. Many people who are infected with HIV do not have any symptoms at all for 10 years or more.

The following may be warning signs of advanced HIV infection:

rapid weight loss
dry cough
recurring fever or profuse night sweats
profound and unexplained fatigue
swollen lymph glands in the armpits, groin, or neck
diarrhea that lasts for more than a week
white spots or unusual blemishes on the tongue, in the mouth, or in the throat
pneumonia
red, brown, pink, or purplish blotches on or under the skin or inside the mouth, nose, or eyelids
memory loss, depression, and other neurological disorders

However, no one should assume they are infected if they have any of these symptoms. Each of these symptoms can be related to other illnesses. Again, the only way to determine whether you are infected is to be tested for HIV infection. For information on where to find an HIV testing site, visit the National HIV Testing Resources Web site at www.hivtest.org or call CDC-INFO 24 Hours/Day at1-800-CDC-INFO (232-4636), 1-888-232-6348 (TTY). These resources are confidential. You can also ask your health care provider to give you an HIV test.

You also cannot rely on symptoms to establish that a person has AIDS. The symptoms of AIDS are similar to the symptoms of many other illnesses. AIDS is a medical diagnosis made by a doctor based on specific criteria established by the CDC.

Source: Centers for Disease Control and Prevention, www.cdc.gov/hiv.

More about HIV/AIDS