AIDS:
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system caused by the human immunodeficiency virus (HIV). This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, breastfeeding or other exposure to one of the above bodily fluids.AIDS is considered a pandemic. In 2009, the World Health Organization (WHO) estimated that there are 33.4 million people worldwide living with HIV/AIDS, with 2.7 million new HIV infections per year and 2.0 million annual deaths due to AIDS. In 2007, UNAIDS estimated: 33.2 million people worldwide had AIDS that year; AIDS killed 2.1 million people in the course of that year, including 330,000 children, and 76% of those deaths occurred in sub-Saharan Africa. According to UNAIDS 2009 report, worldwide some 60 million people have been infected, with some 25 million deaths, and 14 million orphaned children in southern Africa alone since the epidemic began.
Genetic research indicates that HIV originated in west-central Africa during the late nineteenth or early twentieth century. AIDS was first recognized by the U.S. Centers for Disease Control and Prevention in 1981 and its cause, HIV, identified in the early 1980s.
Although treatments for AIDS and HIV can slow the course of the disease, there is no known cure or vaccine. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries. Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS pandemic, with health organizations promoting safe sex and needle-exchange programmes in attempts to slow the spread of the virus.
History and origin:
AIDS was first reported June 5, 1981, when the U.S. Centers for Disease Control (CDC) recorded a cluster of Pneumocystis carinii pneumonia (now still classified as PCP but known to be caused by Pneumocystis jirovecii) in five homosexual men in Los Angeles. In the beginning, the CDC did not have an official name for the disease, often referring to it by way of the diseases that were associated with it, for example, lymphadenopathy, the disease after which the discoverers of HIV originally named the virus. They also used Kaposi's Sarcoma and Opportunistic Infections, the name by which a task force had been set up in 1981.In the general press, the term GRID, which stood for gay-related immune deficiency, had been coined.The CDC, in search of a name, and looking at the infected communities coined “the 4H disease,” as it seemed to single out Haitians, homosexuals, hemophiliacs, and heroin users. However, after determining that AIDS was not isolated to the gay community, the term GRID became misleading and AIDS was introduced at a meeting in July 1982. By September 1982 the CDC started using the name AIDS, and properly defined the illness.
The earliest known positive identification of the HIV-1 virus comes from the Congo in 1959 and 1960 though genetic studies indicate that it passed into the human population from chimpanzees around fifty years earlier. A recent study states that a strain of HIV-1 probably moved from Africa to Haiti and then entered the United States around 1969.
The HIV virus descends from the related simian immunodeficiency virus (SIV), which infects apes and monkeys in Africa. There is evidence that humans who participate in bushmeat activities, either as hunters or as bushmeat vendors, commonly acquire SIV. However, only a few of these infections were able to cause epidemics in humans, and all did so in the late 19th—early 20th century. To explain why HIV became epidemic only by that time, there are several theories, each invoking specific driving factors that may have promoted SIV adaptation to humans, or initial spread: social changes following colonialism, rapid transmission of SIV through unsafe or unsterile injections (that is, injections in which the needle is reused without being sterilised), colonial abuses and unsafe smallpox vaccinations or injections, or prostitution and the concomitant high frequency of genital ulcer diseases (such as syphilis) in nascent colonial cities. See the main article Origin of AIDS.
One of the first high profile victims of AIDS was the American actor Rock Hudson, a known homosexual who had been married and divorced earlier in life, who died on 2 October 1985 having announced that he was suffering from the virus on 25 July that year. It had been diagnosed during 1984. A notable British casualty of AIDS that year was Nicholas Eden, a Member of Parliament and son of the late prime minister Anthony Eden. Eden junior, a lifelong bachelor, was also a known homosexual. The virus claimed perhaps its most famous victim yet on 24 November 1991, when British rock star Freddie Mercury, lead singer of the band Queen, died from an AIDS related illness having only announced that he was suffering from the illness the previous day; however he had been diagnosed as HIV positive during 1987. One of the first high profile heterosexual victims of the virus was Arthur Ashe, the American tennis player. He was diagnosed as HIV positive on 31 August 1988, having contracted the virus from blood transfusions during heart surgery earlier in the 1980s. Further tests within 24 hours of the initial diagnosis revealed that Ashe had AIDS, but he did not tell the public about his diagnosis until April 1992.He died, aged 49, as a result of the AIDS virus on 6 February 1993.
A more controversial theory known as the OPV AIDS hypothesis suggests that the AIDS epidemic was inadvertently started in the late 1950s in the Belgian Congo by Hilary Koprowski's research into a poliomyelitis vaccine. According to scientific consensus, this scenario is not supported by the available evidence.
Signs and symptoms::
The symptoms of AIDS are primarily the result of conditions that do not normally develop in individuals with healthy immune systems. Most of these conditions are infections caused by bacteria, viruses, fungi and parasites that are normally controlled by the elements of the immune system that HIV damages.Opportunistic infections are common in people with AIDS. These infections affect nearly every organ system.
People with AIDS also have an increased risk of developing various cancers such as Kaposi's sarcoma, cervical cancer and cancers of the immune system known as lymphomas. Additionally, people with AIDS often have systemic symptoms of infection like fevers, sweats (particularly at night), swollen glands, chills, weakness, and weight loss. The specific opportunistic infections that AIDS patients develop depend in part on the prevalence of these infections in the geographic area in which the patient lives.
Tumors::
Kaposi's sarcoma (KS) is the most common tumor in HIV-infected patients. The appearance of this tumor in young homosexual men in 1981 was one of the first signals of the AIDS epidemic. Caused by a gammaherpes virus called Kaposi's sarcoma-associated herpes virus (KSHV), it often appears as purplish nodules on the skin, but can affect other organs, especially the mouth, gastrointestinal tract, and lungs. High-grade B cell lymphomas such as Burkitt's lymphoma, Burkitt's-like lymphoma, diffuse large B-cell lymphoma (DLBCL), and primary central nervous system lymphoma present more often in HIV-infected patients. These particular cancers often foreshadow a poor prognosis. Epstein-Barr virus (EBV) or KSHV cause many of these lymphomas. In HIV-infected patients, lymphoma often arises in extranodal sites such as the gastrointestinal tract. When they occur in an HIV-infected patient, KS and aggressive B cell lymphomas confer a diagnosis of AIDS.
Invasive cervical cancer in HIV-infected women is also considered AIDS-defining, it is caused by human papillomavirus (HPV).
In addition to the AIDS-defining tumors listed above, HIV-infected patients are at increased risk of certain other tumors, notably Hodgkin's disease, anal and rectal carcinomas, hepatocellular carcinomas, head and neck cancers, and lung cancer. Some of these are causes by viruses, such as Hodgkin's disease (EBV), anal/rectal cancers (HPV), head and neck cancers (HPV), and hepatocellular carcinoma (hepatitis B or C). Other contributing factors include exposure to carcinogens (cigarette smoke for lung cancer), or living for years with subtle immune defects.
Interestingly, the incidence of many common tumors, such as breast cancer or colon cancer, does not increase in HIV-infected patients. In areas where HAART is extensively used to treat AIDS, the incidence of many AIDS-related malignancies has decreased, but at the same time malignant cancers overall have become the most common cause of death of HIV-infected patients. In recent years, an increasing proportion of these deaths have been from non-AIDS-defining cancers.
Exams and Tests
The following is a list of AIDS-related infections and cancers that people with AIDS may get as their CD4 count decreases. In the past, having AIDS was defined as having HIV infection and getting one of these additional diseases. Today, according to the Centers for Disease Control and Prevention, a person may also be diagnosed as having AIDS if they have a CD4 cell count below 200 cells/mm3, even if they don't have an opportunistic infection.
AIDS may also be diagnosed if a person develops one of the opportunistic infections and cancers that occur more commonly in people with HIV infection. These infections are unusual in people with a healthy immune system.
CD4 cells are a type of immune cell. They are also called "T cells" or "helper cells."
Many other illnesses and their symptoms may develop, in addition to those listed here.
Common with CD4 count below 350 cells/mm3:
- Herpes simplex virus -- causes ulcers/small blisters in the mouth or genitals, happens more frequently and usually much more severely in an HIV-infected person than in someone without HIV infection
- Tuberculosis -- infection by tuberculosis bacteria that mostly affects the lungs, but can affect other organs such as the bowel, lining of the heart or lungs, brain, or lining of the central nervous system (brain and spinal cord)
- Oral or vaginal thrush -- yeast infection of the mouth or vagina
- Herpes zoster (shingles) -- ulcers/small blisters over a patch of skin, caused by reactivation of the varicella zoster virus, the same virus that causes chickenpox
- Non-Hodgkin's lymphoma -- cancer of the lymph nodes
- Kaposi's sarcoma -- cancer of the skin, lungs, and bowel associated with a herpes virus (HHV-8). It can happen at any CD4 count, but is more likely to happen at lower CD4 counts, and is more common in men than in women.
Common with CD4 count below 200 cells/mm3:
- Pneumocystis carinii pneumonia, "PCP pneumonia," now calledPneumocystis jiroveci pneumonia, caused by a fungus
- Candida esophagitis -- painful yeast infection of the esophagus
- Bacillary angiomatosis -- skin lesions caused by a bacteria calledBartonella, which may be acquired from cat scratches
Common with CD4 count below 100 cells/mm3:
- Cryptococcal meningitis -- fungal infection of the lining of the brain
- AIDS dementia -- worsening and slowing of mental function, caused by HIV itself
- Toxoplasma encephalitis -- infection of the brain by a parasite, called Toxoplasma gondii , which is frequently found in cat feces; causes lesions (sores) in the brain
- Progressive multifocal leukoencephalopathy -- a disease of the brain caused by a virus (called the JC virus) that results in a severe decline in mental and physical functions
- Wasting syndrome -- extreme weight loss and loss of appetite, caused by HIV itself
- Cryptosporidium diarrhea -- Extreme diarrhea caused by one of the parasites that affect the gastrointestinal tract
Common with CD4 count below 50/mm3:
- Mycobacterium avium -- a blood infection by a bacterium related to tuberculosis
- Cytomegalovirus infection -- a viral infection that can affect almost any organ system, especially the large bowel and the eyes
In addition to the CD4 count, a test called HIV RNA level (or viral load) may be used to monitor patients. Basic screening lab tests and regular cervical Pap smears are important to monitor in HIV infection, due to the increased risk of cervical cancer in women with a compromised immune system. Anal Pap smears to detect potential cancers may also be important in both HIV-infected men and women, but their value is not proven.
Prevention
- See the article on safe sex to learn how to reduce the chance of acquiring or spreading HIV, and other sexually transmitted diseases.
- Do not use illicit drugs and do not share needles or syringes. Many communities now have needle exchange programs, where you can get rid of used syringes and get new, sterile ones. These programs can also provide referrals for addiction treatment.
- Avoid contact with another person's blood. Protective clothing, masks, and goggles may be appropriate when caring for people who are injured.
- Anyone who tests positive for HIV can pass the disease to others and should not donate blood, plasma, body organs, or sperm. Infected people should tell any sexual partner about their HIV-positive status. They should not exchange body fluids during sexual activity, and should use whatever preventive measures (such as condoms) will give their partner the most protection.
- HIV-positive women who wish to become pregnant should seek counseling about the risk to their unborn children, and methods to help prevent their baby from becoming infected. The use of certain medications dramatically reduces the chances that the baby will become infected during pregnancy.
- The Public Health Service recommends that HIV-infected women in the United States avoid breast-feeding to prevent transmitting HIV to their infants through breast milk.
- Safe-sex practices, such as latex condoms, are highly effective in preventing HIV transmission. HOWEVER, there remains a risk of acquiring the infection even with the use of condoms. Abstinence is the only sure way to prevent sexual transmission of HIV.
The riskiest sexual behavior is unprotected receptive anal intercourse. The least risky sexual behavior is receiving oral sex. Performing oral sex on a man is associated with some risk of HIV transmission, but this is less risky than unprotected vaginal intercourse. Female-to-male transmission of the virus is much less likely than male-to-female transmission. Performing oral sex on a woman who does not have her period has a low risk of transmission.
HIV-positive patients who are taking antiretroviral medications are less likely to transmit the virus. For example, pregnant women who are on effective treatment at the time of delivery, and who have undetectable viral loads, give HIV to their baby less than 1% of the time, compared with about 20% of the time if medications are not used.
The U.S. blood supply is among the safest in the world. Nearly all people infected with HIV through blood transfusions received those transfusions before 1985, the year HIV testing began for all donated blood.
If you believe you have been exposed to HIV, seek medical attention IMMEDIATELY. There is some evidence that an immediate course of antiviral drugs can reduce the chances that you will be infected. This is called post-exposure prophylaxis (PEP), and it has been used to prevent transmission in health care workers injured by needlesticks.
There is less information available about how effective PEP is for people exposed to HIV through sexual activity or injection drug use. However, if you believe you have been exposed, discuss the possibility with a knowledgeable specialist (check local AIDS organizations for the latest information) as soon as possible. Anyone who has been raped should be offered PEP and should consider its potential risks and benefits.
