- NEW YORK -- The HIV virus
has jumped from primates to people on at least seven separate occasions
in recent history, not twice as is commonly thought.
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- And people in Cameroon are showing up with symptoms of
HIV, but are testing negative for both the virus and its primate equivalent
SIV, the virus from which HIV is thought to have evolved. That suggests
that new strains of an HIV-like virus are circulating in wild animals and
infecting people who eat them, sparking fears that such strains could fuel
an already disastrous global HIV pandemic.
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- The warnings come from experts who gathered this week
for the annual meeting of the Society for Conservation Biology at Columbia
University, New York. They say that deforestation and the trade in bush
meat are creating the ideal conditions for new diseases to emerge, as people
have ever closer contact with exotic animals that harbour novel pathogens.
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- The conference reports follow the discovery earlier in
2004 that simian foamy virus, another disease that infects monkeys, has
been found in bush-meat hunters and three different species of primates.
As yet, it has not caused ill-effects, but it could mutate into something
more insidious.
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- "Basically, this is a virus looking for a disease,"
says William Karesh, director of the World Conservation Society's field
veterinary programme.
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- Small game
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- Despite those concerns, we still do not have a clear
idea of how many wild animals are killed and eaten, David Wilkie, co-chair
of the Bushmeat Crisis Task Force (BCTF), told the conference. He has carried
out the first-ever survey of daily bush-meat consumption by rural communities
in Gabon.
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- Over two years, he documented a flourishing, but previously
unrecognised, informal trade in bush meat, where rural communities hunted
and ate small game, having already caught most available primates. He thinks
official studies of bush meat sold in markets account for only 40 per cent
of the total bush meat eaten in the country.
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- "In the Congo basin alone, between one and five
million metric tonnes of bush meat was consumed last year," says Heather
Eves, head of the BCTF, a non-governmental organisation that monitors the
trade.
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- And the dangers of eating such animals are real. The
BCTF points out that SIV infection has now been reported in 26 different
species of African nonhuman primates, many of which are hunted and sold
as food.
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- Wake-up call
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- The bush-meat trade is not the only way new diseases
could jump into humans. The trade in wildlife, both for agriculture and
as pets, is a major global business estimated to be worth billions of dollars.
In 2002 alone, for instance, over 38,000 mammals, 365,000 birds, two million
reptiles, 49 million amphibians, and 216 million fish were imported into
the US.
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- In 2003, monkeypox jumped from pet prairie dogs to their
human masters. That "was just a gentle wake-up call," says Tonie
Rocke, an epidemiologist with the US Geological Survey. Previously the
disease had only been known to infect humans after bush-meat hunters ate
red colobus monkeys.
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- The trade in exotic farmed meat also appears to have
sparked an unusual outbreak of a common human parasite called Trichinella.
In 2004, a farmed crocodile in Papua New Guinea was discovered with Trichinella,
which was only thought to infect mammals, after being fed wild pig meat
(Emerging Infectious Diseases, vol 10, p 1507).
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- In 1999, another farmed crocodile in Zimbabwe was similarly
infected. "There is a strong chance that infected crocodiles may be
in other countries, and could infect humans who eat them," says Edoardo
Pozio, a parasitologist at Rome's institute of public health. People in
Papua New Guinea who eat crocodile meat have already been found to have
the parasite, which can cause fever, rashes, and respiratory and neurological
problems in humans.
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- Rocke says there are few safeguards to prevent the spread
of diseases through the wildlife trade, and is calling for stricter import
and quarantine restrictions.
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