21 Ocak 2008 Pazartesi

Acquired Immune Deficiency Syndrome: The Facts


The first cases of acquired immune deficiency syndrome (AIDS) were reported in the U.S. in June of 1981. The occurrence of the syndrome among homosexual men, intravenous (IV) drug abusers and, later, blood transfusion recipients and persons with hemophilia suggested a transmissible agent as the cause. In 1984, scientists identified a retrovirus, human immune deficiency virus (HIV), also known as human T-Iymphotropic virus type III/lymphoadenopathy, associated virus (HTLV-III/LAV), as the primary cause of AIDS. In 1985, screening tests to detect antibodies to HIV were licensed, allowing identification of infected individuals and the screening of the blood supply. Researchers have been able to map the genetic structure of HIV and to demonstrate the nature of the immune defect. Ongoing research is aimed at identifying risk factors and preventive strategies, evaluating antiviral drugs, developing drugs to augment the immune system, and developing a vaccine.

An estimated 1,000,000 Americans have been infected by the HIV virus. The virus has been isolated from various bodily fluids including blood, semen, saliva, tears, urine, breast milk and cerebrospinal fluid. Transmission of HIV occurs primarily through four major routes: sexual contact, intravenous drug use, blood transfusions and perinatal contact with an infected mother. The screening of donated blood since 1985 for HIV antibodies has virtually eliminated blood transfusion as a risk for acquiring AIDS in the U.S. 95% of the cases of AIDS reported in the U.S. have belonged to the following high risk groups: homosexual and bisexual men, 73%; IV drug abusers, 17% (11% of homosexual and bisexual men also inject drugs); blood transfusion recipients, 2%; persons with blood clotting disorders or hemophilia, 1%; heterosexual contacts of persons in the above groups, 1%; and infants born to mothers with AIDS or HIV infection, 1%.

All persons with AIDS or with antibodies to HIV are considered carriers of the virus and capable of transmitting it to others. It is believed that most people with antibodies to HIV will remain free of AIDS symptoms. The ratio of persons infected with HIV to those with AIDS is estimated currently at between 100:1 to 50:1. The three-year incidence of AIDS among persons with the HIV infection ranges from 8% to 34.2% in selected municipal studies. Estimates are that 10% to 30% of infected persons will develop AIDS within 5 years. For persons who develop AIDS, the overall fatality rate in April of 1986 was 54%. At the end of two years following diagnosis of AIDS, however, the fatality rate was over 75%. At five years, the fatality rate was about 90%.

90% of AIDS patients are between 20-49 years of age. The loss of years of potential life before age 65 due to AIDS is nearly the same as for cancer in single men 25-44 years of age. The economic costs of AIDS are considerable, totalling an estimated $4.1 billion in 1985. Data cited here are changing rapidly and represent the situation only as of 1986.

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