Bush-meat trade breeds new HIV

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Bush-meat trade breeds new HIV
09:00 09 August 04

The HIV virus has jumped from primates to people on at least seven separate occasions in recent history, not twice as is commonly thought.
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.
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.
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.
Basically, this is a virus looking for a disease," says William Karesh, director of the World Conservation Society's field veterinary programme.

Small game
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.

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.
"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.
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.

Wake-up call

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.

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).

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.

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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