Spread of HIV Strain Began in 1940, Spurred by War

Strains of HIV largely limited to West Africa appear to have first infected humans in the 1940s, and the current epidemic involving these strains may have originated in 1955-1970 as a result of war, researchers said Monday. The current report focuses on HIV-2, which is less readily transmitted than HIV-1 and appears slower to progress to AIDS. Although HIV-1 infection has grown into a worldwide epidemic, HIV-2 has remained largely confined to West Africa, where it infects approximately 1 percent of the population. HIV-2 appears to have its predecessor in a strain of simian immunodeficiency virus present in sooty mangabeys.

By comparing HIV-2 samples taken from people with SIV samples taken from sooty mangabeys and other primates that acquired SIV from sooty mangabeys, researchers estimate that the two subtypes of HIV-2 that became epidemics first infected humans around 1940-1945. Study author Dr. Anne-Mieke Vandamme of Katholieke Universiteit Leuven in Belgium said the jump of HIV-2 from sooty mangabeys to humans may have been a result of bushmeat slaughtering or hunting -- the same process that may have enabled HIV-1 to infect humans.

Researchers also discovered evidence suggesting that Guinea-Bissau, the presumed site of origin of HIV-2, experienced a significant increase in new HIV-2 infections in 1955-1970. And that epidemic continues today, Vandamme said. The African region experienced a war of independence against the Portuguese in 1963-1974. The fact that the dramatic spread of HIV-2 in the region coincided with this event suggests that war may have encouraged an increase in infections in the region, Vandamme and colleagues said.

War may have spawned a regional HIV-2 epidemic by increasing the number of people who received unsterile injections in hospitals, the authors suggested. Reports from the region note that army-trained doctors started campaigns to inoculate residents of Guinea-Bissau. Indeed, the first reported cases of HIV-2 in Europe occurred among Portuguese soldiers returned from the independence war, the authors wrote. The full report, "Tracing the Origin and History of the HIV-2 Epidemic," is published in the May 12th online Proceedings of the National Academy of Sciences (2003;10.1073/pnas.0936469100).

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