Wild Animal Trade Plays Role in Bird Flu Spread, Scientists Say
May 31 (Bloomberg) — The legal and illegal trade of wild birds is playing a role in spreading the H5N1 avian flu virus that’s killed 127 people, scientists said.
“We still don’t understand this movement of wildlife,” William Karesh, the New York-based director of the field veterinary program at the Wildlife Conservation Society said today at a conference in Rome. “We have good records for legal trade, but that’s only a bit of what’s going on and it’s probably not where the problems are.”
About 350 million live animals are moved worldwide to become pets or serve other domestic purposes in a trade worth about $20 billion a year. About one-quarter of this trade is thought to be illegal and so isn’t inspected or tested. Disease outbreaks resulting from wildlife trade have caused hundreds of billions of dollars of economic damage globally, Karesh said.
Scientists from more than 100 countries are meeting in Rome to try to shift the focus of bird flu prevention back to the animals that incubate the disease. The H5N1 virus has killed almost two of every three people infected this year, leading governments to buy antivirals, including Roche Holding AG’s Tamiflu, and to sponsor vaccine development. Focusing on controlling the disease in animal populations would be better, the United Nations Food and Agriculture Organization says.
“We have to focus on this issue of trade because it’s the most frequent way if spreading disease from one region to another,” said Joseph Domenech, chief veterinary officer at the Rome-based FAO. “We’re talking about illegal trade here as well, which is much more difficult to regulate. This includes legal and illegal trade in wild birds which is quite significant and often ignored.”
Health officials are worried the H5N1 virus may change into a form easily spread among people, touching off a pandemic similar to the one that began in 1918 in which as many as 50 million people died. Since 2003, H5N1 is known to have infected 224 people in 10 countries, killing 127 of them, according to the World Health Organization in Geneva.
Wild fowl in the pet or exotic bird trade may carry parasites, bacteria and viruses that don’t cause disease in the host animal and become dangerous when introduced to new geographic areas or to new host species. Dangerous strains of both the avian flu virus and Newcastle’s disease, another ailment that can affect birds, have been found in internationally traded non-domestic birds.
Decreasing contact among different species, including that between humans and birds, may be a better way of tackling the disease than trying to eliminate the virus or the wild species that may harbor them, Karesh said.
More Monitoring Needed
“Focusing efforts at markets to regulate, reduce, or, in some cases, eliminate the trade in wildlife could provide a cost- effective approach to decrease the risks in disease for humans, domestic animals and wildlife,” he said.
In addition to monitoring trade, more work needs to be done to study the presence of the H5N1 virus in wild birds, scientists at the conference said.
The FAO and partners including not-for-profit Wetlands International, based in Wageningen, Netherlands, and the Paris- based French Agricultural Research Center for International Development started an 18-month study of the disease in wild birds in January. They haven’t yet been able to find an instance of the virus in wild birds collected in Africa and parts of Europe, said Nicholas Gaidet, a researcher at the French center.
Avian flu virus was found in about 3 percent of the 4,893 samples collected. Those found are referred to as low-pathogenic strains though because they don’t cause severe disease and typically only infect specific organs, such as the respiratory tract and gut. The researchers will continue to collect and take samples from birds and expand the surveillance coverage to new regions, Gaidet said.
The research is aimed at determining the role that wild birds play in the spread of the disease. H5N1 is rampant in poultry farms in Africa, but the inability of researchers to find the virus in wild birds in the area suggests that trade rather than migration may have introduced the virus.
“We haven’t found a needle, but we haven’t looked through enough haystacks yet either,” said Juan Lubroth, head of infectious diseases at the FAO.
Some scientists suggested though that the H5N1 virus hasn’t been found because the studies may be flawed. Researchers need to give more details about the low-pathogenic strains that they’re finding in the birds, said Henry Niman, the president of Pittsburgh-based Recombinomics Inc., a closely-held company that looks at the emergence of new infectious diseases. These infections are commonly found in wild birds and if the researchers aren’t finding these strains, it may also indicate that they’re overlooking the H5N1 virus, he said.
“The low-path detection rate would certainly provide insight into the relevance of the negative data on H5N1,” Niman said.
Researchers have been focused on sampling feces, though the H5N1 virus is primarily found in the respiratory tract rather than the digestive system, said Ron Fouchier, a researcher at the Department of Virology at Erasmus Medical Center in Rotterdam, Netherlands. He recommends that researchers take samples from the throats of birds too.
“I think we’ve been looking at the wrong end of the bird,” he said.
To contact the reporters on this story:
Carey Sargent in Geneva at Csargent3@bloomberg.net
Last Updated: May 31, 2006 07:21 EDT
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