Human Immunodeficency Virus (HIV), virus of the retrovirus family, the agent that causes Acquired Immune Deficiency Syndrome (AIDS). A person infected with HIV gradually loses immune function and becomes vulnerable to numerous infractions that can lead to AIDS.
The virus was discovered in association with AIDS by three separate teams of researchers: first in 1983 by Luc Montagnier and scientists at the Pasteur Institute in Paris, and then in 1984 by Robert Gallo and his colleagues at the National Cancer Institute, on the National Institutes of Health in Bethesda, Maryland, and by Jay Levy and his colleagues at the University of California at San Francisco. The virus undergoes an incubation period before disease onset, they infect blood cells and the nervous system and suppress the immune system.
Then, the virus does a process known as reverse transcription, which converts their genomic RNA into DNA. Currently there are two identified types of HIV, HIV 1 and HIV 2. HIV infects white blood cells such as CD4 T-lymphocytes. The HIV uses the CD4 as a receptor to which it attaches to. This causes the HIV to fuse with the cell membrane; fusion allows the virus to enter the cell eventually killing the CD4 T-lymphocytes. This is what paralyzes the immune system and causes AIDS. Acquired Immune Deficiency Syndrome (AIDS), specific group of diseases or conditions that result from suppression of the immune system related to infection with HIV.
A person with HIV gradually loses their CD4 T-lymphocytes (T-cells) and becomes vulnerable to pneumonia, fungus infections and other common ailments. With the loss of immune function, a clinical syndrome develops over time and eventually results in death due to opportunistic infections or cancers. When a person is diagnosed as HIV-positive it does not necessarily mean that they have AIDS, although people who are HIV often are mistakenly said to have AIDS. An HIV-positive person can live up to ten years without developing any of the clinical illnesses that define and a diagnosis of AIDS.
It is estimated that in 1995, worldwide, 18. 4 million people were living with HIV or AIDS. – The cumulative number of reported AIDS cases from the beginning of the epidemic in 1981 – 148,705 cases were reported in the United State in the past year. – 343,000 deaths from reported AIDS cases have occurred since the beginning of the epidemic. In the United States, the cumulative total number of reported AIDS cases among the following White, not Hispanic (46. 80% of total case count)256,461 African-American (34. % of total case count)189,004 Hispanic/Latino (17. 1% of total case count)96,613 Asian/Pacific Islander (0. 7% of total case count)3826 American Indian/Alaskan Native (0. 3% of total case count)1439 – The cumulative number of cases among women is 78,654, or 14. 4% of total case count. – The cumulative number of cases among men is 462,152, or84. 3%oftotalcasecount. – The percentage of the cumulative total number of reported AIDS cases among the following age group is: Progression from the point of HIV to AIDS may take six to ten or more years.
The progression is monitored by using surrogate markers and clinical endpoints. Surrogate markers for various stages of HIV include the declining number of CD4 T-cells. In 1996, it became evident that the actual amount of HIV in a persons blood – called the viral burden – could be used to predict the progression to AIDS, regardless of the persons CD4 T-cell count. Also, a persons immune response to the virus – that is, the persons ability to produce antibodies against HIV is also used to determine the progression of AIDS.
Within 1 to 3 weeks after infection, most people experience flu-like symptoms such as fever, headache, skin rash, tender lymph nodes and a vague feeling of discomfort which last about 1 to 2 weeks. During this phase, the acute retroviral syndrome phase, HIV reproduces very high concentrations into the blood, mutates frequently, circulates through the blood and establishes infections throughout the body, especially in the lymphoid organs. Following this phase, the person enters a asymptomatic phase (symptom free) with can last ten or more years.
However, the virus is replicating and causing destruction of the immune system. Eventually, the immune system weakens and enters early symptomatic phase, which can last from a few months to several more years. The CD4 T-cells are now rapidly falling and infections may occur. After a persons CD4 T-cells fall under 200 per cub mm of blood, AIDS is defined. Excessive weight loss and debilitating fatigue occurs and the immune system is in a severe state of failure. Eventually, advanced AIDS sets in and the CD4 T-cell number falls below 50 per cubic mm of blood.
Death due to severe life-threatening opportunistic infections and cancers occurs within one to two years. The most common infections is Pneumocystis carinii pneumonia (PCP) caused by a fungus. A bacterial pneumonia, such as, tuberculosis, and Mycobacterium avium causes fever, weight loss, anemia and diarrhea. Gastrointestinal tract infedtions commonly cause diarrhea, weight loss, anorexia, and fever. A disease caused by protozoal parasites, especially toxoplasmosis of the nervous system, are common.
Thrush of the mouth by the fungus Candida albicans; Crytococcus which is a major cause of meningitis with 13% of people with AIDS get; Histoplasma capsulatum with 10% of people with AIDS causing weight loss, fever and respiratory complications or severe central nervous system complications if the infection reaches the brain. Viral infections such as herpes are common in AIDS; cytomegalovirus infects the eyesight and can cause blindness; Epstein-Barr with results in cancerous transformation of blood cells; also, herpes simplex virus types 1 and 2 with result in progressive sores around the mouth and anus.
Cancerous infections, being B-cell lymphoma and Kapoks Sarcoma which are common in homosexual gay man. HIV is spread through the exchange of body fluids, primarily semen, and blood products. It is most commonly spread by sexual contact with an infected person. The virus is spread to the bloodstream of the uninfected person by way of small abrasions that may occur as a consequence of sexual intercourse. It is also spread by sharing needles or syringes; most commonly intravenous drugs. A rare form of contraction is blood transfusions or use of blood-clotting factors (1 in 450,000 to 600,000 unit of blood).
Infected mothers can passed it to the child either before or during childbirth or through breastfeeding. Health-care workers have been infected after being stuck with needles containing HIV-infected blood or less frequently after blood contacts the workers open cut or splashes into a mucous membrane (eyes or nose). Only one case demonstrated that a health-care provider passed to patients (a dentist to six patients). The actual risk of a health care provider passing the virus to a patient is minimal.
Fear continues to concern the potential transmission of other means, such as casual contact (kissing an infected person) in a household, school, workplace, or food-service settings. No scientific evidence to support any of these fears has been found. Saliva has a protein called secretory leukocyte protease inhibitor which prevent HIV from infecting white blood cells. Nor is there any evidence that insects can transmit the disease. There are different treatments to help suppress the HIV virus. One class of anti-HIV drugs is RT inhibitors.
The RT inhibitors, which are licensed by the United States Food and Drug Administration, are AZT (zidovudine), ddi (didanosine), ddC (zalcitabine), d4T (stavudine), and 3TC (lamivudine). The drugs work as DNA-chain terminators. The most effective time to take these drugs is when first infected. Because the virus mutates rapidly and there are many different strains of HIV, some people may become drug-resistant to RT inhibitors. The combination of AZT and 3TC have been shown effective in preventing the AIDS virus from developing resistance to AZT.
The combination has also shown a boost in CD4 T-cell counts and lower levels of HIV in the blood. Protease inhibitors were approved by the FDA in 1995 and have shown to cripple a key enzyme called protease, which is vital to reproduction of HIV. When protease is blocked, HIV makes copies of itself that cannot infect new cells. HIV infection does not spread inside the body as quickly as it does without protease inhibitors. These drugs can reduce up to 99% of the virus in the blood, but more viruses can remain elsewhere in the body.
The virus will become dormant or latently infected meaning they are infected but still waiting to make new virus. One drug will not win the battle alone, therefore, researchers believe other anti-HIV need to be administered. Bone marrow xenotransplantation has also been performed. A man with AIDS received a bone marrow transplant from a baboon (baboons are resistant to HIV) in hopes to restore the patients immune system. Not enough time has elapsed to support or dismiss the possible hope of a new, improved life for the man. Gene therapy and immunization are other possible alternatives in helping to prevent the virus from spreading.
Also, the HIV Notification Law, which congress and some physicians are trying to pass. They feel that to prevent the spread of HIV, sex partners should be notified for testing. They believe that by doing so, this would break the cycle of transmission by identifying those at risk. The law would require physicians to not only confidentially report positive results but also the names of the patients sex partners to local state health departments. Then the department would contact the partners without revealing the patients name.
Thirty-three states require physicians to report the names of people who test seropositive and 42 states require or permit partner notification. A federal law already mandates notification of spouses. On the other hand, the Anonymous HIV testing options has proven that people sought testing and medical care earlier in the course of HIV disease than did persons tested confidentially. This option is a safety valve for those who dont wish to have their names reported. Educating the public about routes of HIV transmission and personal measures that reduce the risk of infection.
Safe sex, abstinence or monogamy and the use of latex condoms are one measure. Another one is needle-exchange programs which have been implemented by the government. Health care settings with include protective clothing and proper instrument disposal. Medical interns and residents follow universal precautions and treat every patient as a possible source of exposure to blood-borne diseases and are required to attend orientation that include presentations about the use of gloves, masks, and gowns as well as other safety precautions.
Researchers have found the elective cesarean sections performed before the onset of labor can reduce HIV transmission from mother to baby. Women who were pregnant with HIV, had good CD4 count and viral load, were given AZT after the first trimester which reduce the transmission rate to 1%. Reducing perinatal transmission is the biggest success story of the HIV epidemic, says Lynne Mofenson, of the National Institute of Child Health and Human Development. AIDS falls from top ten causes of death; teen deaths, infant mortality, homicide all decline.
Age adjusted death rates from HIV infection in the US declined an unprecedented 47% from 1996 to 1997, and HIV infection fell from 8th to 14th among leading causes of death in the US over the same time. Ages 25-44, HIV dropped from leading cause of death in 1995 to the third-leading in 1996 and in 1997 fifth-leading. Age-adjusted HIV death rate of 5. 9 deaths per 100,000 is the lowest rate since 1987. The 1997 rate is less than half the 1992 rate (12. 6) and almost one-third the rate in 1995 (15. 6).
