AIDS - Description
AIDS is considered one of the most serious public health problems in modern history. In 1998 the U.S. Centers for Disease Control and Prevention (CDC) estimated that between 650,000 and 900,000 Americans were HIV-positive. HIV-positive means that a person has been infected with the virus. The CDC estimates that as of 1998 some 300,000 Americans were living with AIDS.
Nearly half of all AIDS patients are gay or bisexual men. About one quarter are intravenous drug users. An intravenous drug user is someone who takes drugs illegally by means of injection with a hypodermic needle. About 18 percent of AIDS patients are women. In addition, between one thousand and two thousand children are born infected with HIV each year.
AIDS is a far worse problem in some parts of the world than it is in others. The World Health Organization (WHO) estimates that 32.2 million adults and 1.2 million children worldwide were infected with HIV or AIDS as of 1998. Most of these cases occur in the developing countries of Asia and Africa.
At one time, people were concerned that HIV could be transmitted by casual contact, such as shaking hands or eating in the same room with an infected person. Scientists now know that the virus is never passed during casual contact of this kind. HIV can be transmitted in several ways:
SEXUAL CONTACT. HIV can be transmitted any time two people exchange bodily fluids, such as semen or blood. Most forms of sexual contact involve some exchange of bodily fluids. The risk of contracting the virus increases if an individual has a high number of different sexual partners or practices unsafe sex. Unsafe sex refers to having sexual contact without using any method to prevent the exchange of bodily fluids. In the United States and Europe, most cases of sexually transmitted HIV infection occur during homosexual contact, that is, between two people of the same gender. In Africa, Asia, and other parts of the world, HIV is transmitted primarily through heterosexual contact, that is, between two people of opposite genders.
EXPOSURE TO CONTAMINATED BLOOD OR BLOOD PRODUCTS. Early in the HIV epidemic, the virus was sometimes transmitted during blood transfusions. Blood taken from one person with the HIV infection was given to a second person for medical treatment, he or she also received the virus. Hemophiliacs (pronounced hee-muh-FIH-lee-ak; see hemophilia entry), people who require blood transfusions quite often, were especially at high risk for HIV infection.
In the 1980s, new rules were adopted for the screening of donated blood. Since that time, the rate of HIV infections from contaminated blood and blood products has been greatly reduced. However, HIV infection is still spread by this method among illegal drug users. These men and women often share the same needle with each other. When they do so, the blood from one person is easily transferred to a second person. If the first person is infected with HIV, the virus may be passed on.
- Acute retroviral syndrome:
- A group of symptoms resembling mononucleosis that are the first sign of HIV infection in 50 to 70 percent of all patients and 45 to 90 percent of women.
- AIDS dementia complex:
- A type of brain dysfunction caused by HIV infection that causes confusion, difficulty thinking, and loss of muscular coordination.
- Antibody:
- A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.
- Antigen:
- Any substance that stimulates the body to produce antibody.
- Autoimmunity:
- A condition in which the body's immune system (the system that fights disease and infection) produces antibodies in response to its own tissues or blood components instead of foreign particles or microorganisms.
- CD4:
- A type of protein molecule in human blood that is present on the surface of 65 percent of immune cells. The HIV virus infects cells that have CD4 surface proteins, and as a result, depletes the number of T cells, B cells, natural killer cells, and monocytes in the patients blood. Most of the damage to an AIDS patient's immune system is done by the virus's destruction of CD4 lymphocytes.
- Hairy leukoplakia of the tongue:
- A white area of diseased tissue on the tongue that may be flat or slightly raised. It is caused by the Epstein-Barr virus and is an important diagnostic sign of AIDS.
- Hemophilia:
- Any of several hereditary blood coagulation disorders occurring almost exclusively in males. Because blood does not clot properly, even minor injuries can cause significant blood loss that may require a blood transfusion, with its associated minor risk of infection.
- Human immunodeficiency virus (HIV):
- A transmissible virus that causes AIDS in humans. Two forms of HIV are now recognized: HIV-1, which causes most cases of AIDS in Europe, North and South America, and most parts of Africa; and HIV-2, which is chiefly found in West African patients. HIV-2, discovered in 1986, appears to be less virulent that HIV-1 and may also have a longer latency period.
- Immunodeficient:
- A condition in which the body's immune response is damaged, weakened, or is not functioning properly.
- Kaposi's sarcoma:
- A cancer of the connective tissue that produces painless purplish red or brown blotches on the skin. It is a major indication that a patient has AIDS.
- Latent period:
- Also called incubation period, the time between infection with a disease-causing agent and the development of the disease.
- Lymphocyte:
- A type of white blood cell that is important in the formation of antibodies and that can be used to monitor the health of AIDS patients.
- Lymphoma:
- A cancerous tumor in the lymphatic system that is associated with a poor prognosis in AIDS patients.
- Macrophage:
- A large white blood cell, found primarily in the bloodstream and connective tissue, that helps the body fight off infections by ingesting the disease-causing organism. HIV can infect and kill macrophages.
- Monocyte:
- A large white blood cell that is formed in the bone marrow and spleen. About 4 percent of the white blood cells in normal adults are monocytes.
- Nucleoside analogues:
- A medication that interferes when HIV tries to make copies of itself inside cells.
- Opportunistic infection:
- An infection by organisms that usually don't cause infection in people whose immune systems are working normally.
- Persistent generalized lymphadenopathy (PGL):
- A condition in which HIV continues to produce chronic painless swellings in the lymph nodes during the latency period.
- Protease inhibitors:
- The second major category of drug used to treat AIDS that works by suppressing the replication of the HIV virus.
- T Cells:
- Lymphocytes that originate in the thymus gland. T cells regulate the immune system's response to infections, including HIV. CD4 lymphocytes are a subset of T lymphocytes.
- Wasting Syndrome:
- A progressive loss of weight and muscle tissue caused by AIDS.
NEEDLE STICKS. Health professionals sometimes poke themselves accidentally with a needle when drawing blood from a patient. If the patient is infected with HIV, the health professional may receive the virus from the needle stick. The risk of transmitting the virus this way is very small (virtually zero) when health professionals use standard procedures for drawing blood and handling needles.
PREGNANCY AND BIRTH. A woman infected with HIV can transmit the virus to her unborn child. The virus passes through the amniotic fluid (the fluid surrounding the unborn baby) and into the child's bloodstream. A young baby can also get the virus from an infected woman during breast feeding.
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