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Monday, 17 March 2014

Aids Pictures Aids Symptoms Patient Virus Lesions Ribbon Rash Pictures i n Africa Symbol Victims Images pictures wallpapers photos

Aids Pictures biography

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What is HIV?
HIV is the Human Immunodeficiency Virus and it attacks your body's immune system. The virus destroys CD4 cells, which help your body fight diseases. HIV can severely damage your immune system and lead to AIDS.
How is HIV treated?
HIV treatment may reduce the amount of HIV in your blood (called "viral load"). Treatment may also help to increase the number of CD4 cells in your blood which help fight off other infections.

As soon as HIV was identified in 1983, scientists started trying to understand where it had come from, when it had arisen, and why it had spread. Were they too late? To answer most of their questions, they would have had to witness the virus's evolution. Scientists can track new pathogens such as SARS and avian flu because they produce obvious symptoms almost immediately. But HIV is a stealth virus that takes as many as 10 years to present symptoms; by the time researchers knew enough to wonder about its origins, those origins were in the distant past.

For the last 23 years, scientists have been trying to peer into that past. Jon Cohen, a correspondent for Science who has written extensively about the virus, compares the work to fossil hunting, using a few precious shreds of evidence to construct a possible history. "Everybody's always looking for certainty. It doesn't exist [in this field]," he says. "In a sense it's all theory."

Nonetheless, the theory rests on facts, and at least a few of them are undisputed -- including, most significantly, HIV's family tree. There are two species of the virus, HIV-1 and HIV-2. The first evolved from a simian immunodeficiency virus (SIV) found in chimpanzees, while the second came from an SIV in a type of monkey called the sooty mangabey.

african aids patient
Part One: Chapter Three Politics & Tracking AIDS' History
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first picture of the aids virus
Part One: Chapter Four Scientific Breakthroughs
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HIV-1, which is responsible for the vast majority of AIDS cases worldwide, is divided into three groups -- the "major" group M, and the much rarer "outlier" group O and "new" group N -- that have diverged over years of mutation and evolution. Within the M group -- which makes up 90 percent of all infections worldwide -- there are at least nine strains, known as "clades," of HIV-1 that are constantly mutating and merging with each other, creating yet more new varieties. "The M group epidemiologically has overwhelmed what else is out there," says Dr. Beatrice Hahn of the University of Alabama-Birmingham, who has conducted much of the research into HIV's origin. HIV-2, on the other hand, is not as virulent and largely confined to West Africa, where it originated.

In May 2006, an international group of researchers led by Hahn answered two major questions about the origin of HIV-1 M, the deadliest and most widespread form of the virus: Where was its cradle, and what kind of chimp did it come from? Answering the questions was literally messy work -- researchers collected 599 waste samples from wild chimpanzees and analyzed the viral particles they contained -- but the results were immaculate. Three populations of Pan troglodytes troglodytes living in southern Cameroon provided the crucial data. Two of those populations currently carry SIVs that are molecular dead ringers for HIV-1 M, while many chimps in the third group are infected with an SIV remarkably similar to HIV-1 N. Group O's simian sibling is probably lurking in other chimp populations in West Central Africa, says Hahn, adding that she has "a pretty good idea where it's going to be … and we're going to find it."