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英国essay论文精选范文：“AIDS virus”，这篇论文讨论了艾滋病的病毒。艾滋病被称为“世纪瘟疫”，是一种由逆转录病毒引起的人体免疫防御系统方面的疾病。一旦感染艾滋病，它就会攻击人体的免疫系统，使人体丧失免疫功能。一旦人体的免疫功能没了，就很容易感染各种病毒，最后导致死亡。

Today, forty million people are believed to be living with the acquired immunodeficiency syndrome (AIDS) - the 3rd leading killer in the world. It is been given the name as AIDS because Acquired means that the disease is not hereditary but develops after birth from contact with a disease causing agent or virus; Immunodeficiency means that the disease is characterized by a weakening of the immune system while Syndrome will refers to a group of symptoms that collectively indicate or characterize a disease. In this case the AIDS are believed that it involved in the development of certain infections and/or cancers, as well as in reducing the number of certain cells in a person's immune system.

Each year, there are an outstanding number of cases being reported, this indicates that each year, this ‘killer’ is violently attacking people’s live; the human life now is being endanger. The origin of AIDS has been being a puzzle for the scientists ever since the illness came to light in the early in 1980s. But there is a study suggests that the AIDS is caused by the Human Immunodeficiency Virus (HIV) where this virus was transmitted from animals to human in the 1940s. In the year of 1959, a man who looked healthy walked into a hospital clinic, in order to donate his blood for a Western backed study of some type blood disease in the central African city of Leopoldville. This is the 1st and the last time for the doctor who took his blood ever seen him again as about his news was never heard from again. The doctors do analyze his blood sample; they froze it in a test tube and stored it. But when the time passed through, the doctors had forgot about it. After a quarter- century, in the mid of 1980s, some researchers were doing some research on the growing AIDS epidermis and took a second look at the blood and they discovered that the blood does contained HIV, the virus which cause AIDS. Thus, it is believe that the Leopoldville sample is the oldest specimen of the AIDS virus ever isolated and till now the scientists believe that this specimen may help in solving this mystery ‘background’ of this virus.

But how can the ‘healthy’ guy above get infected by the HIV virus? Where does this virus originate from? As mentioned early, the virus can transmitted from animal to human. This is no longer a surprise neither for the scientists nor the researchers because they have known the viral can transfer between animals and human for a long time, and this process is known as zoonosis. HIV actually is a lentivirus; it usually attacks the immune system. Lentivirus are derived from a large group of viruses which known as retroviruses. The name of ‘lentivirus’ gives the meaning of ‘slow virus’ because they usually take a long period to ‘show’ the effects against the human body. This type of viruses is common as they can be found in a number of different animals, for instance sheep, horses and cattle. However, the most interesting lentivirus in term of the invagination into the origin of HIV is the Simian Immunodeficiency Virus (SIV) that affects monkeys.

In February 1999, a group of researchers from the University of Alabama was declaimed that they had successful found a type of SIVcpz (SIV chimpanzees) which is nearly identical to HIV-1.  This particular strain was identified from a frozen sample which taken from a captive member of the sub- group of chimpanzees known as Pan Troglodytes (P. t. troglodytes), where this population is very common in the west- central of Africa.

目录

Cause of Acquired Immune Deficiency Syndrome (AIDS)

Symptoms of Acquired Immune Deficiency Syndrome (AIDS)

Early Symptoms

Later Symptoms

Opportunistic Infections

Symptoms of the Immune System

Symptoms of the GI Tract

Respiratory Symptoms

Symptoms of the Skin and Mucous Membranes

Neurological / Emotional Symptoms

Tumors and malignancie

Diagnosis of AIDS

Treatment of AIDS

HIV Transmission

HIV in the Environment

Households

Businesses and Other Settings

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From the onset of the HIV epidemic, there has been concern about transmission of the virus by biting and bloodsucking insects. However, studies conducted by researcher at CDC and elsewhere have shown no evidence of HIV transmission through insects. Even in areas where there are many cases of AIDS and large populations of insects such as mosquitoes. Lack of such outbreaks, despite intense efforts to detect them, supports the conclusion that HIV is not transmitted by insects.

The results of experiments and observations of insect biting behavior indicate that when an insect bites a person, it does not inject its own or a previously bitten person’s or animal’s blood into the next person bitten. Rather, it injects saliva, which acts as a lubricant or anticoagulant so the insect can feed efficiently. Such diseases as yellow fever and malaria are transmitted through the saliva of specific species of mosquitoes. However, HIV lives for only a short time inside an insect and, unlike organisms that are transmitted via insect bites, HIV does not reproduce (and does not survive) in insects. Thus, even if the virus enters a mosquito or another sucking or biting insect, the insect does not become infected and cannot transmit HIV to the next human it feeds on or bites. HIV is not found in insect feces.

There is also no reason to fear that a biting or bloodsucking insect, such as a mosquito, could transmit HIV from one person to another through HIV-infected blood left on its mouth parts. Two factors serve to explain why this is so--first, infected people do not have constant, high levels of HIV in their bloodstreams and, second, insect mouth parts do not retain large amounts of blood on their surfaces. Further, scientists who study insects have determined that biting insects normally do not travel from one person to the next immediately after ingesting blood. Rather, they fly to a resting place to digest this blood meal.

Reference

Michael T.Madigan, John M.Martinko, Jack Parker, 1997. Brock Biology of Microorganisms. 8th Ed. London: Prentice-Hall.

Information of H IV (March, 2010).

The Structure of HIV (March, 2010).

Introduction to HIV and AIDS drug treatment (Dec, 2009).

AIDS information Switzerland (November, 2009).

HIV Transmission (June, 2009).

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