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Flies may transmit HIV
19/06/2002 13:44 - (SA)
Johannesburg - A report in the British medical journal Lancet, has
raised the possibility that an insect might be able to transmit the
Aids-causing human immunodeficiency virus (HIV) - a finding likely
to cause scientists to re-examine the origin of the current HIV
pandemic and how HIV got into the human population in the first
place.
The journal Lancet Infectious Diseases quotes and comments on
work by German researchers showing that the stable fly (Stomoxys
calcitrans) is capable of feeding on HIV infected blood and
regurgitating infectious virus.
The German researchers are from prestigious institutions: the
Universities of Freiburg and Bonn, and the renowned Max Planck
Institute for Biophysical Chemistry.
It has been generally held that biting insects are incapable of
transmitting HIV because they ingest blood from their victims and
inject saliva into their victims via different routes, said Dr
Andrew Jamieson, medical director of Netcare Travel Clinics, in a
statement.
But the stable fly is different as it uses the first part of its
digestive tract to store ingested blood. Regurgitated material from
stable flies fed on HIV-containing blood has been shown by two of
the researchers, Brandner and Kloft, to contain intact HIV.
It is known that stable flies can transmit other viruses,
including a virus which causes a disease of horses, the equine
anaemia virus. The equine anaemia virus is classified as a
retrovirus, as is HIV. The findings by the German scientists raise
the possibility that stable flies feeding on blood covered bush
meat (a euphemism for chimpanzee meat) may have transmitted the
chimpanzee form of HIV, known as SIV or simian immunodeficiency
virus, to humans.
Biting a human after feeding on infected bush meat, the stable
fly may have given the chimpanzee virus the bridge it needed to
cross the species barrier and infect humans. Jamieson said: "The
German theory is highly speculative, and it would be premature to
blame the stable fly for starting the HIV pandemic."
He added that travellers into Africa could take reassurance from
the fact that mosquitoes are unable to transmit HIV - a question
frequently directed to Netcare Travel Clinics.
"Even if it transpires that the stable fly can cause HIV in
humans, the same would not be true of mosquitoes."
- SAPA
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