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er 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.

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

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文献

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