By using old samples of HIV, researchers have constructed a “molecular clock” to determine the “rate at which mutations accumulate” in the virus. The resulting evidence suggests that HIV was probably infecting people as early as the 1880s. Improvements in transportation such as new railroads, urbanization or the expansion of communities and cities, in addition to the emergence of a fluid global economy have allowed HIV to expand and explode. Currently, there is no cure for HIV. From Reuters South Africa, South Africa:

Researchers think the growth of cities — and high-risk behavior associated with urban life — may have helped the virus to flourish. There is no cure for AIDS, which is most commonly transmitted through sexual contact.

Prior estimates put the origin of HIV at 1930. But Michael Worobey of the University of Arizona in Tucson now believes HIV began infecting humans between 1884 and 1924.

The research is based on 48-year-old gene fragments dug from a wax-embedded lymph node from a woman in Kinshasa in the Democratic Republic of Congo, formerly Zaire.

The 1960 sample is the second-oldest genetic sequence of HIV-1 group M, the main strain of the virus responsible for the AIDS pandemic.

The oldest sequence came from a 1959 blood sample given by a man in Kinshasa, formerly known as Leopoldville.

“Once you have two you can line them up and compare them,” Worobey said in a telephone interview.

“Once you do that, you see these two sequences are very different. That means the virus had already been there for a long time even by 1959 or 1960.”

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