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HIV (human immunodeficiency virus)
What is HIV?Human immunodeficiency virus (HIV) is the retrovirus that causes AIDS (acquired immune deficiency syndrome). There are two different types of HIV: HIV-1, which is the most common type and is found worldwide, and HIV-2, which is found predominantly in West Africa. HIV/AIDS is characterized by the loss of specialized immune cells called CD4+ T cells, and the persistent and progressive deterioration of immune function. HIV recognizes the CD4 receptor, and enters and infects immune cells expressing CD4. As the virus multiplies, it damages or destroys these and other cells, impairing the immune system and leaving the individual susceptible to infections and illness ranging from pneumonia to cancer. Many of the opportunistic infections that cause severe health problems in the setting of HIV/AIDS (such as those caused by viruses, bacteria, parasites or fungi) are efficiently controlled by the immune system in healthy individuals. How many people get HIV?According to the Joint United Nations Programme on HIV/AIDS, in 2004, nearly 40 million people globally were estimated to be living with HIV. In the United States alone, the Centers for Disease Control and Prevention estimated that at the end of 2003, there were an estimated 1,039,000 to 1,185,000 persons in the United States living with HIV/AIDS, with 24 percent to 27 percent undiagnosed and unaware of their HIV infection (most recent statistics available). How is HIV spread?HIV is carried in certain body fluids, including blood, semen, vaginal secretions and breast milk, and is transmitted when virus-infected fluids contact and enter the bloodstream of another person. HIV is usually transmitted through sexual intercourse, the sharing of contaminated needles or syringes, or from mother to infant during pregnancy, childbirth or breast-feeding. In the health care setting, workers have been infected with HIV after being stuck with needles containing HIV-infected blood or, less frequently, after infected blood gets into a worker’s open cut or a mucous membrane (for example, in the eyes or inside the nose). Can HIV infection be prevented?Preventing infection depends on avoiding contact with blood and other fluids that might contain HIV. Sexual IntercourseTo avoid infection through sex, the only sure way is not to have anal, vaginal or oral sexual intercourse, or to have sex only with a monogamous partner who is not infected. Using a new latex condom (without an oil-based lubricant) correctly every time during vaginal, anal or oral sex can greatly lower risk of infection. Drug UsageNeedles or injection equipment used to inject drugs or steroids should never be shared. Drugs should be avoided, as they impair judgment. Vertical TransmissionResearch indicates that transmission of HIV from mother to child can be reduced with maternal antiretroviral therapy. Workplace ContaminationHealth care workers may decrease risk of contamination by employing universal precautions (also known as standard precautions), which means treating everybody’s blood and body fluids as if infected with HIV. Using needleless systems, retractable syringes and other devices that have built-in safety features can prevent needle sticks. Barrier protection (such as latex gloves, masks and goggles) must be used to shield all naturally wet skin (such as in the mouth, nose and eyes) and all broken, cut or torn skin. How is HIV infection diagnosed?Because the symptoms of HIV infection (listed below) are similar to many other diseases, the only way to diagnose HIV infection is through a blood test. In addition, many people who are infected with HIV do not have any symptoms at all for many years. The EIA (enzyme immunoassay) is the standard screening test used to detect the presence of antibodies to HIV and is usually used with a confirmatory test such as the western blot. Test results are typically available in one to two weeks. There is also a rapid test for detecting antibody to HIV that provides results in five to 30 minutes, although the availability of this rapid HIV test varies from one place to another. The rapid HIV test is considered to be just as accurate as the EIA. The following may be warning signs of infection with HIV:
How is HIV infection treated?There is currently no cure for HIV infection or AIDS. The management of HIV/AIDS involves drugs designed to target the virus itself as well as to treat opportunistic infections and illnesses that affect HIV/AIDS patients. Compounds that act to interfere with viral replication include reverse transcriptase inhibitors, which inhibit the virus from making new copies of its genome, and protease inhibitors, which block assembly and maturation of new viral particles. These antiviral agents are often taken in combination in a regimen known as highly active antiretroviral therapy (HAART). Such combination therapy may reduce the level of virus circulating in the bloodstream and restore the level of CD4 immune cells. HAART has been a major factor in reducing the number of AIDS deaths in the United States and has greatly improved the health of many HIV/AIDS patients. However, these drugs are highly toxic and can cause severe side effects. Moreover, HIV is capable of continuously mutating into new drug-resistant strains, which poses a serious challenge to the long-term efficacy of existing medications. Furthermore, the accessibility of HAART to infected people worldwide is limited. Education, prevention and treatment remain high priorities in international efforts to control the HIV/AIDS epidemic. Intensive efforts are focused on the development of a safe, effective and affordable preventative or therapeutic vaccine for HIV infection. Research is ongoing to identify new targets for anti-HIV medications and new methods to restore the ability of the immune system to defend against HIV infection. Below are additional resources that may be helpful to you.
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