Bloodsucking Fly May Have Transferred SIV to Humans From Chimps, German Scientists Say

Bloodsucking stable flies may have transmitted SIV, an HIV-like virus, from chimpanzees to humans, "unleash[ing]" the HIV epidemic on humans, according to German scientists, BBC News reports (BBC News, 3/14). Many AIDS researchers believe that HIV was originally an animal virus that "leapt the species barrier" to humans in the early 20th century. Scientists have theorized that an SIV-infected ape bit a human or was eaten uncooked by a human, thus transmitting the virus. However, Werner Kloft of the University of Bonn, Manfred Eigen of the Max Planck Institute for Biophysical Chemistry in Goettingen and Freiburg University researcher Gerhard Brandner report in the Mar. 23 issue of New Scientist and in the German journal Naturwissenschaften that they believe the virus was transmitted from ape to human through a bloodsucking fly. While most bloodsucking insects, like mosquitos, cannot transmit HIV, the stable fly sucks blood when it feeds and then regurgitates some of that blood at its next feeding. If the blood is regurgitated into an open wound, any virus in the blood could be passed on (Agence France-Presse, 3/13). The key "precondition for transmission of HIV" is that the fly does not digest the blood, keeping any virus in the blood unharmed by digestive enzymes, according to the researchers. The researchers suggest that HIV could have been transmitted through these flies "for years" without being recognized. However, these "rare" HIV infections now "pale into insignificance" next to the spread of HIV through unprotected sex and shared needles, according to BBC News. "It's an interesting theory and no more," David Mabey, professor at the London School of Hygiene and Tropical Medicine, said, adding that theories such as this one "distract attention from the main public health message, which is 90% of infections are transmitted by sex or from mothers to infants. So the message is to practice safe sex and not to worry about being bitten by flies" (BBC News, 3/14).