Asian flu dynamics
Posted here Tuesday, February 03, 2004 at 9:36:58 AM 
The great problem of asian flu, and that is the tendency of larg populations of humans to be dependent on large populations of very stressed anaimals.
Culling measures now must be looked at in a different way since chickens are a very important source of protein in the region," Stöhr said. "The balance must be struck between ensuring human health against the virus while making sure we do not undermine these countries in other ways." While the avian disease outbreak does not technically fall under the authority of the World Health Organization, the agency has been watching with great concern as migratory birds appear to carry the disease across borders. "One of the more likely scenarios is that the distribution of the virus around Asia may have occurred through migratory birds," Stöhr said. "A dead falcon was found to be excreting H5N1 ten days ago on the shores of Hong Kong." If migratory birds are indeed spreading the disease, then avian flu could potentially spread to chickens in Europe.
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"There are migratory bird routes connecting Siberia with Europe, but I don't dare to speculate," Stöhr said. "It is certainly true that migratory birds play a role, but we have not completely divined which one."
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International Herald Tribune
With avian influenza showing no sign of slowing its spread across Asia, officials at the World Health Organization are warning that the danger to human health is increasing daily.
. "The human outbreak is completely dependent in dynamic and scope on the avian influenza outbreak," said Klaus Stöhr, the World Health Organization's top influenza expert. "We have the potential for a real global health emergency." On Tuesday, Indonesia joined Cambodia, China, Japan, Laos and South Korea in reporting that forms of the H5N1 avian virus have hit poultry farms, while Taiwan and Pakistan have reported the presence of a different avian influenza. Tens of millions of chickens have been slaughtered by governments across the region in a mass culling intended to contain the flu. So far the human death toll from the species-jumping disease stands at 12, after Vietnam and Thailand on Monday reported a death each from the virus.
. Most cases have been traced to direct contact with sick birds, but there has been one unconfirmed case of human-to-human transmission in Vietnam. Although number of human victims of the bird flu outbreak is still modest in comparison with the number of people infected with SARS in the epidemic that struck Asia last year, the World Health Organization warns that a strain of avian influenza adapted to humans would present a much greater danger.
. "So far we only have a handful of cases, so from one perspective it is a relatively low concern," Stöhr said. "On the other hand, we could face a full-blown pandemic if the virus began circulating among humans." Such a pandemic would make the roughly 8,000 infections and 800 deaths attributed to SARS last year seem very small in scale.
. "Major influenza pandemics of the last century infected anywhere from 10 percent up to 40 percent of the world's population," Stöhr said. "In one pandemic an estimated 40 to 50 million people died when the world population was one-third of where it stood now," he added, referring to the pandemic of Spanish flu in 1918. Influenza greatly outstrips SARS in its ability to infect, spread and mutate.
. SARS baffled scientists at the outset with its ability to jump across borders, but the spread quickly came under control after the World Health Organization issued a travel warning. Testing for fever, a symptom of SARS, almost entirely stopped its spread through airports.
. Limiting the spread of the SARS in a highly contaminated hospital setting, such as Hong Kong's Prince of Wales Hospital, proved almost impossible at the outset. But by the end of the outbreak, once scientists determined that most transmission took place through a cough or a sneeze, hospitals maintained control by resurrecting old-fashioned barrier nursing techniques.
. In contrast with SARS, which requires close personal contact for infection, an influenza virus can float across a room and still infect.
. Also, while scientists feared SARS would mutate into a more virulent form, the disease remained stable; the ability of influenza to mutate is one of its chief dangers.
. "The avian influenza is changing significantly," Stöhr said. "It is swapping genes with other forms of other H5 virus and other viruses and has indicated a propensity to cause a public health hazard as well as agricultural problems." The danger in swapping genes with other strains of influenza is that the strain could become more virulent or contagious. The most worrying aspect of the avian influenza so far, however, has been its ability to spread among chickens across Asia.
. "We have never seen an outbreak of avian influenza that has spread to so many countries in such a short period of time and affected such a large area," Stöhr said. "The scale brings things to a whole different level when you look for solutions." The influenza currently spreading among chickens in Asia, the H5N1 strain, first jumped to humans in Hong Kong in 1997. Brought under control in the past by slaughtering millions of birds in a matter of days, such solutions are increasingly difficult.
. "Culling measures now must be looked at in a different way since chickens are a very important source of protein in the region," Stöhr said. "The balance must be struck between ensuring human health against the virus while making sure we do not undermine these countries in other ways."
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