Acquired Immunodeficiency Syndrome Essay Research Paper Acquired — страница 3

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vehicle of spread are semen and blood. The virus is found in the vagina, but only in relatively small numbers. This explains the possibility of infection from female to male through vaginal intercourse, and the even greater ease which this can occur in the opposite direction. DNA sequences identical to those of HIV were found in the genomes of African insects by Jean-Claude Chermann and his team in 1986. This, however, is insufficient to implicate insects as vectors of the human disease, especially since, at the time of writing, epidemiological evidence argues strongly against thishypothesis. Nevertheless, it is not impossible that insects could play some role in the natural history of the retrovirus. The AIDS VirusAIDS is a deadly syndrome, or collection of clinical features,

that is known to be caused by the human immunodeficency virus (HIV, previously calledHTLV-III or LAV). HIV damages the immune system – the system that ordinarily protects the body against infection – leaving a person especially susceptible to other infections and to variety of malignancies. AIDS itself is actually the end of infection, many people have no visible symptoms, whereas others experience various types of mild illness or more serious health problems that can be debilitating but do not fit the diagnostic criteria for full-blown case of AIDS. While there is some uncertainty about how many of those infected with HIV will ultimately develop AIDS, it is increasingly apparent that the majority will eventually all die of this disorder.How the AIDS Virus WorksThe clinical

manifestations or first symptoms and signs of AIDS seem to have five aspects, some of which are completely independent of the others. 1. Serious abnormalities of the immune system with the inevitable consequences of opportunistic infections. 2. Reaction of functional components of the immune system to the virus. 3. Infection of the brain and resultant thinking disorders. 4. Induction of certain kinds of abnormal cell growth, such as B-cell lymphoma and Kaposi’s sarcoma. 5. Miscellaneous disease due to an increased incidence of infection with disease-causing microbes (pathogens). Kaposi’s SarcomaSince cancer usually occur within one or more of one’s internal organs, they spread invisibly, sparing the patient and others the additional psychological horror of having to watch

them grow. Kaposi’s sarcoma, however, often occurs on the skin surface or in the mouth or other visible body openings. First described in 1872 by the Austrian dermatologist Moricz Kaposi, Kaposi’s sarcoma remained a rare tumor, unknown even to some physicians, until the recent full force impact of AIDS. Kaposi’s sarcoma was first se in older men of Jewish and Italian ancestry, and later in others of Mediterranean ancestry, especially Greeks. It was much later found in Central Africa, but this time in the young and old men. The cause of these tumors has been ascribed to genetic mechanisms, and some results support the possibility of inheriting susceptibility to the classic form. Cancer, as we have seen, is clonal – the tumor cells are derived from one original transformed

cell, and spreading occurs because some cells acquire the capacity to move to another site and grow there (metastasis). But Kaposi’s sarcoma seems to begin in many places at the same time. In the case of AIDS-associated Kaposi’s sarcoma, the lesions that may be found in the internal organs, mucosal surfaces of the gastrointestinal system, and skin, all appear to develop de novo rather than by metastasis from an original tumor site.Paths of TransmissionIn the last five years, clinical observations, epidemiological statistics, and laboratory experiments have all confirmed that HIV is not very contagious and that its routes of transmission are quite limited. It is transmitted only by three routes: sexual contact, direct inoculation or injection of blood in tissues or blood

vessels, or mother-child transmission through the placenta or breast milk. Sexual transmission is without doubt the most common means of infection. In semen and in vaginal secretions of infected persons, the virus is present in small quantities in a free state and in a much greater quantity in close association with the infected cells. Historically, transmission between homosexual partners was the first recognized path of infection. Since the epidemic began, with an outbreak in the American homosexual community, there was a fairly long delay before doctors recognized the possibility of spread by heterosexual relations. For several years, female to male transmission was considered to be an unlikely event, but epidemiological surveys in Africa have dispelled all doubt that this