October 04, 2008

HIV turns one hundred years old this year.

(We think. Although it could actually be at least twenty years older than that: +/-20 years is the current degree of uncertainty.)

As published in Nature this week, Paul Sharp and Beatrice Hahn have succeeded in isolating an HIV sample from a preserved tissue sample dated 1960, which turns out to have been significantly differentiated from the HIV found in another preserved tissue sample, dated 1959. At this point in the virus' history among human beings, even accounting for its known high genetic variability, the virus would have had to be circulating in the human reservoir for over fifty years already to account for the degree of genetic difference.

HIV is a long onset virus, but even so, left to itself in a rural setting, the circle of infection would have eventually and invisibly killed itself off, in a manner similar to Ebola viruses today. It would just have taken about ten years longer.

Fortunately for the virus, the patterns of thousands of years were about to be upset. The automated transportation industry began to take off, and transportation links were built. (Happy centennary, Model T Ford.) Rural areas around the world became more accessible to their urban cousins. Kinshasa grew.

At some point one or more persons carrying the HIV virus came to Kinshasa, or maybe the truck routes which transported produce and supplies developed first, along with their sexual support networks. The virus found a new foothold, among a vastly increased pool of human beings. In time it jumped continents, and then oceans.

HIV/AIDS continued to kill. We thought it was "just" tuberculosis, then.

Today an estimated 33.2 million people around the world live with with one or more of three primary strains of HIV-1 or HIV-2/AIDS: 0.6% of the world's population. Roughly two and a half million people still catch it every year, and about 2.1 million die from it every year.

In effect, it has become part of our genetic heritage.

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