AIDS-related Complex is a more advanced level of HIV infection. Symptoms generally include the symptoms of lymphadenopathy, plus abnormal body conditions revealed by laboratory tests, and/or the presence of one or more opportunistic infections.
A person with ARC has a discomforting illness. His or her everyday activity may be restricted and he or she is probably manifesting bouts of illness that require short-term or long-term medical treatment in and out of the hospital.
AIDS is the "full-blown" syndrome, also called "frank" AIDS. Patients suffering from AIDS often have any number of the opportunistic diseases listed in Figure 6. These diseases develop because of the widespread failure of the immune system. Drug treatments are available for many of these infections; but, without the support of the immune system, the drugs fail to cure the disease fully or are unable to keep the disease from returning. These opportunistic infections, curable under other circumstances, cause the death of most AIDS patients.
Unfortunately, up to now, most estimates of the number of HIV-infected people have been overblown. As early as 1983, selected scientists, and consequently the media, trumpeted estimates of 1 to 3 million. At the time, these estimates were exaggerated. Now, however, the AIDS epidemic is 10 years old, and scientists have tabulated over 200,000 total registered AIDS cases, and also have HIV screening results from hundreds of hospitals, hundreds of testing centers, and millions of armed forces recruits. Consequently, the current I million estimate carries a lot of weight.
In order for a person to catch AIDS (HIV infection), the Human Immunodeficiency Virus (HIV) must travel from the inside of one person to the inside of another person, arriving with its RNA strand(s) intact. Then the virus, or its intact RNA strand(s) must get into the new host's bloodstream and then successfully find and enter a T-cell. Once inside a host cell, HIV can prepare for replication. After replication, replica viruses infects other host cells, probably attaching to new host cells when the infected host cell collides with other cells in the bloodstream.
Generally, more than one virus enters the body at one time. More likely, a person encounters dozens, hundreds, or thousands of viruses (or virus-infected cells) during exposure. The more viruses present, the better the chance of one or more viruses succeeding in finding a host cell and replicating.
Viruses are not able to enter the body through intact skin. Therefore viruses must enter the body through an open wound(s) or one of a number of possible body openings. Most of these body openings contain mucous membranes. Mucous membranes are thin tissues which protect many openings and passages in the human body. These membranes secrete mucus. Which contains anti-germ chemicals and keeps the surrounding tissues moist. There are mucous membranes in the mouth, inside the eyelids, in the nose and air passages leading to the lungs, in the stomach, along the digestive tract, in the vagina, in the anus, and inside the "eye" of the penis. Many viruses, if placed on the surface of a mucous membrane, can travel through the membrane and enter the tiny blood vessels inside.
The mucous membranes of the eyes and mouth are often doorways into our bodies for highly infectious viruses such as the flu. You can catch the flu from a person in the following manner: the person coughs in his or her hand, you shake hands soon afterward, and then your virus-carrying hand touches your eye or mouth.
The flu is highly infectious because the flu virus lives in the lungs, throat, and sinuses. Therefore, a high concentration of flu viruses is present in the sputum of an infected person. (Sputum is the substance expelled by coughing or by clearing the throat. Concentration is the number of viruses per unit of volume.) Coughing forces many viruses out of the lungs and into the air or onto the sick person' s hand or handkerchief. The flu virus easily crosses the mucous membrane.
The danger with AIDS is very different. With AIDS, the major infection sites are the bloodstream and the central nervous system. While HIV-carrying macrophages (roving white blood cells that engulf invaders, but are susceptible to HIV infection) are found in the connective tissues of the lung and in oral and mucous membranes, the number of viruses present does not seem great. Thus, HIV is present in low concentrations, if at all, in saliva and sputum. So coughing should not expel a large quantity of HIV, if any. Apparently, HIV cannot cross the mucous membrane very easily, and large concentrations of HIV are probably necessary.
In an infected person, HIV is found in any body fluid or substance which contains lymphocytes (T4-cell and company). Substances containing lymphocytes include: blood, semen, vaginal and cervical secretions, mother's milk, saliva, tears, urine, and feces.
The presence of HIV within a substance does not necessarily mean the substance is capable of transmitting HIV infection. All of these substances are capable, in theory, of transmitting disease; but in reality, the most dangerous substances seem to be blood, semen, and cervical and vaginal secretions, and perhaps feces. Despite a lot of looking, no one has been able to find a clear cut case of saliva causing transmission, although kissing theoretically could. See "Kissing."
The concentration of HIV in these substances is very important when it comes to infectivity. (Concentration is "number of viruses per unit of volume") If a substance contains a high concentration, that is, a lot of viruses, then it is more likely HIV can be transmitted by the substance. Below a certain concentration of viruses, the substance can not effectively transmit HIV infection.
The importance of concentration is illustrated by the situation with sperm and pregnancy. If a male's semen contains fewer than 20 million sperm cells per milliliter (cubic centimeter), than it is unlikely that the male will be able to impregnate a female. Similarly, if the concentration of a virus is too low in sputum or any other substance, then it is unlikely to transmit infection.
In theory, saliva can transmit HIV infection but, so far, it doesn't seem to have happened in real life. Kissing is discussed in more detail in the next section.
If HIV is contained in any of the aforementioned substances (blood, semen, vaginal and cervical secretions, urine, feces, mother's milk, saliva, tears) and these substances leave the body, the HIVs in these substance are capable of remaining infectious until these substances dry up, depending on circumstances, probably a matter of minutes or hours. If any of these substances stay moist, viruses contained in them can survive much longer. For example, in "water' and blood solutions (10% blood, 90% saline), HIV can survive at room temperature for 2 weeks. In refrigerated blood, such as blood used for transfusions, HIV can survive indefinitely.
Instructions on how to handle these substances follow in the Chapter "Preventing AIDS."
The transmission of the virus from the mother to the child can occur in utero during pregnancy andintrapartum at childbirth. In the absence of treatment, the transmission rate between the mother and child is around 25 percent.[28] However, where combination antiretroviral drug treatment andCesarian section are available, this risk can be reduced to as low as one percent.[28]
Breast feeding also presents a risk of infection for the baby.
In general if infected blood comes into contact with any open wound, HIV may be transmitted. This transmission route can account for infections in intravenous drug users, hemophiliacs and recipients of blood transfusions (though most transfusions are checked for HIV in the developed world) and blood products. It is also of concern for persons receiving medical care in regions where there is prevalent substandard hygiene in the use of injection equipment, such as the reuse of needles in Third World countries. Health care workers such as nurses, laboratory workers, and doctors have also been infected, although this occurs more rarely. People who give and receivetattoos, piercings, and scarification procedures can also be at risk of infection.
Since transmission of HIV by blood became known medical personnel are required to protect themselves from contact with blood by the use of Universal precautions.
The majority of HIV infections are acquired through unprotected sexual relations. Sexual transmission can occur when infected sexual secretions of one partner come into contact with thegenital, oral, or rectal mucous membranes of another. In high-income countries, the risk of female-to-male transmission is 0.04% per act and male-to-female transmission is 0.08% per act. For various reasons, these rates are 4 to 10 times higher in low-income countries.[34]
The correct and consistent use of latex condoms reduces the risk of sexual transmission of HIV by about 85%.[35] However, spermicide may actually increase the male to female transmission rate due to inflammation of the vagina.[36]
A meta-analysis of 27 observational studies conducted prior to 1999 in sub-Saharan Africa indicated that male circumcision reduces the risk of HIV infection.[37] However, a subsequent review indicated that the correlation between circumcision and HIV in these observational studies may have been due to confounding factors.[38] Later trials, in which uncircumcised men were randomly assigned to be medically circumcised in sterile conditions and given counseling and other men were not circumcised, have been conducted in South Africa,[39] Kenya[40] andUganda[41] showing reductions in HIV transmission for heterosexual sex of 60 percent, 53 percent, and 51 percent respectively. As a result, a panel of experts convened by WHO and theUNAIDS Secretariat has "recommended that male circumcision now be recognized as an additional important intervention to reduce the risk of heterosexually acquired HIV infection in men."[42] Research is clarifying whether there is a historical relationship between rates of male circumcision and rates of HIV in differing social and cultural contexts.[citation needed]
On the other hand, some South African medical experts have expressed concern that the repeated use of unsterilized blades in the traditional circumcision of adolescent boys may actually be spreading HIV.[43]
Bugchasing and giftgiving is the active pursuit to contract and transmit HIV, respectively.
Controversy surrounding the discovery of HIV was intense after French scientist Luc Montagnier and American researcher Robert Gallo both claimed to have discovered it, in 1983 and 1984 respectively.[22] In 1987 the dispute was initially settled on a political level with both teams receiving equal credit.[22] In 1991 a study confirmed that the samples in Gallo's laboratory had in fact originated in Montagnier's.[22] In 1994 the U.S. government conceded that the French should receive the lion's share of the credit.[23]
The Karolinska Institute awarded half of the 2008 Nobel Prize in Physiology or Medicine to Montagnier and his colleague Françoise Barré-Sinoussi 'for their discovery of "human immunodeficiency virus"'. The other half went to Harald zur Hausen for unrelated work onHuman Papilloma Virus.[24] Gallo was reported to have said that it was "a disappointment" not to have been included, but that all three of the award's recipients deserved the honor. [25] The Karolinska Institute's press release stated "Soon after the discovery of the virus, several groups contributed to the definitive demonstration of HIV as the cause of acquired human immunodeficiency syndrome (AIDS)."[HIV is thought to have originated in non-human primates in sub-Saharan Africa and transferred to humans early in the 20th century.[16] The first paper recognizing a pattern of opportunistic infections was published on 4 June 1981.[17]
Two species of HIV infect humans: HIV-1 and HIV-2. Both species of the virus are believed to have originated in West-Central Africa and jumped species (zoonosis) from a non-human primate to humans. HIV-1 is thought to have originated in southern Cameroon after jumping from wild chimpanzees (Pan troglodytes troglodytes) to humans during the twentieth century.[18][19] It evolved from a Simian Immunodeficiency Virus (SIVcpz)[20] HIV-2, on the other hand, may have originated from the Sooty Mangabey (Cercocebus atys), an Old World monkey of Guinea-Bissau, Gabon, and Cameroon.[15]
New World Monkeys are an interesting exception to the transmission of HIV. Their immunity is believed to be caused by retrotransposition of the Cyclophilin gene into an intron of TRIM5. The result is fusion gene that provides the owl monkey with resistance to HIV-1 infection. [21]
HIV is a member of the genus Lentivirus,[11] part of the family of Retroviridae.[12] Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a longincubation period.[13] Lentiviruses are transmitted as single-stranded, positive-sense, envelopedRNA viruses. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase, along with host cellular co-factors,[14] so that the genome can be transcribed. After the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells.
There are two strains of HIV known to exist: HIV-1 and HIV-2. HIV-1 is the virus that was initially discovered and termed LAV. It is more virulent, relatively easily transmitted, and is the cause of the majority of HIV infections globally. HIV-2 is less transmittable and is largely confined to West Africa.[15]
HIV infection in humans is now pandemic. As of January 2006, the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimate that AIDS has killed more than 25 million people since it was first recognized on December 1, 1981. It is estimated that about 0.6 percent of the world's population is infected with HIV.[3] In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children. A third of these deaths are occurring in sub-Saharan Africa, retarding economic growthand increasing poverty.[4] According to current estimates, HIV is set to infect 90 million people in Africa, resulting in a minimum estimate of 18 million orphans.[5] Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.[6]
HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages, and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible toopportunistic infections.
Eventually most HIV-infected individuals develop AIDS. These individuals mostly die fromopportunistic infections or malignancies associated with the progressive failure of the immune system.[7] Without treatment, about 9 out of every 10 persons with HIV will progress to AIDS after 10-15 years. Many progress much sooner.[8] Treatment with anti-retrovirals increases the life expectancy of people infected with HIV. Even after HIV has progressed to diagnosable AIDS, the average survival time with antiretroviral therapy (as of 2005) is estimated to be more than 5 years.[9] Without antiretroviral therapy, death normally occurs within a year.[10] It is hoped that current and future treatments may allow HIV-infected individuals to achieve a life expectancy approaching that of the general public.
Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that can lead to acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threateningopportunistic infections. Previous names for the virus includehuman T-lymphotropic virus-III (HTLV-III),lymphadenopathy-associated virus (LAV), and AIDS-associated retrovirus(ARV).[1][2]
HIV is a virus. Viruses infect the cells that make up the human body and replicate (make new copies of themselves) within those cells. A virus can also damage human cells, which is one of the things that can make a person ill.
HIV can be passed from one person to another. Someone can become infected with HIV through contact with the bodily fluids of someone who already has HIV.
HIV stands for the 'Human Immunodeficiency Virus'. Someone who is diagnosed as infected with HIV is said to be 'HIV+' or 'HIV positive'.
