I apologize if this has already been sent to the list. I haven't
noticed it in the digests I skim every day. This disease and the way
it is handled by health authorities and governments might have
far-reaching effects on birds and birders and birding.

>Science, Vol 310, Issue 5747, 426-428 , 21 October 2005
>News Focus
>AVIAN INFLUENZA:
>Are Wild Birds to Blame?
>Dennis Normile
>
>As H5N1 reaches Europe, scientists debate the role of wild birds but agree
>on the need for greater surveillance
>Almost as soon as H5N1 avian influenza began its deadly sweep across Asia,
>people fingered migratory birds as likely culprits in its spread. Migrating
>birds offer an obvious way to connect the dots of H5N1 outbreaks along the
>east coast of Asia and, in just the past few months, its unexpected
>cross-continent jump to Siberia, Kazakhstan, and Turkey. Moreover,
>researchers have long known that these birds commonly harbor less virulent
>flu viruses, and many wild birds mingle with Asia's free-ranging domestic
>poultry, which have been decimated by H5N1.
>But avian experts have been almost universally skeptical that wild birds
>are spreading the virus. One reason is that sampling of tens of thousands
>of birds has failed to turn up a single healthy wild bird carrying the
>pathogenic strain of H5N1, which has caused the death of more than 100
>million domestic birds--and at least 60 humans--in Asia. Evidence so far
>suggests that H5N1 kills wild ducks and geese nearly as efficiently as it
>does chickens. "Dead ducks don't fly" has been the refrain, as avian
>experts point out that sick and dying birds simply can't spread viruses
>very far. Instead, epidemiologists investigating the virus's jump, even to
>geographically far-flung regions, keep turning up evidence suggesting that
>the poultry trade and other human activities are responsible.
>
>Now, however, evidence implicating wild birds is starting to convince even
>some of the doubters. "Until about 2 months ago, I was pretty skeptical on
>whether wild birds were playing a role," says David Suarez, a virologist
>with the U.S. Department of Agriculture's (USDA's) Southeast Poultry
>Research Laboratory in Athens, Georgia. "But now I feel that there is much
>stronger evidence that wild birds are spreading the virus." What changed
>his mind, he says, was the death of 100 or so ducks, gulls, geese, and
>swans from H5N1 at a remote lake in Mongolia that he believes can't be
>explained by human activities. And, he and others add, in an unexpected
>twist, it's beginning to look as though the culprits might not be the
>long-suspected migratory waterfowl but another yet-unidentified wild species.
>
>The implications are huge. If wild birds are carrying the disease, says
>Suarez, "it will be difficult or impossible to control the spread from
>country to country." Nailing down the answer became even more urgent last
>week with the confirmation that H5N1 has now entered Europe.
>
>Even before that confirmation, the Netherlands ordered farms along
>migratory routes to keep poultry inside, and three German states asked
>farmers to voluntarily take similar precautions. Last month, the European
>Commission rejected proposals to extend such measures throughout the union,
>but E.U. officials were reassessing their stance with the news that H5N1
>has reached Turkey (see p. 417). Everyone recognizes that if wild birds are
>involved, new strategies will be needed to halt the virus's spread to
>domestic flocks--and from them to people. A growing number of scientists
>and organizations are calling for dramatically increased global
>surveillance to profile all viruses circulating in wild birds. Says Kennedy
>Shortridge, a virologist and professor emeritus at the University of Hong
>Kong, "H5N1 is important, but we still need to be on the lookout for other
>flu viruses." The costs of surveillance are small, he says, considering the
>damage that could be done to the poultry industry--or
> From low to high
>One reason migratory waterfowl were high on the list of suspects for
>spreading H5N1 is because they are natural hosts for other bird flu
>viruses. But Ilaria Capua, a virologist at Italy's National Reference
>Laboratory for Avian Influenza in Padua, warns that Anatidae, the family
>that includes ducks and geese, are as genetically distant from gallinaceous
>birds (chickens, turkeys, and quail) as cats are from dogs. The different
>families interact with viruses very differently, she says.
>
>Viruses are subtyped by the forms of two of their surface glycoproteins,
>hemagglutinin (H) and neuraminidase (N). There are 16 forms of
>hemagglutinin and nine of neuraminidase. Viruses are further classified as
>being of low or high pathogenicity. Low-pathogenicity viruses are typically
>carried in a bird's intestinal and respiratory tracts and usually cause
>mild or no symptoms. Highly pathogenic viruses can infect cells throughout
>a bird's body and cause systemic disease and, usually, death.
>
>Waterfowl have been shown to carry low-pathogenicity viruses of virtually
>all possible combinations of H and N, including low-pathogenicity versions
>of H5N1. So far, however, there is no known natural reservoir for highly
>pathogenic avian influenza viruses. They emerge only after
>low-pathogenicity viruses jump from water birds into chickens and turkeys.
>As the virus attempts to adapt to a new host, it somehow acquires the
>ability to infect cells throughout the bird's entire body. This mutation
>from low to high pathogenicity, with a resulting bird flu epidemic among
>poultry, has occurred at least 19 times since 1959. In some cases,
>researchers have traced the virus from its low-pathogenicity form in water
>birds to a low-pathogenicity virus that circulated in poultry before
>becoming highly pathogenic.
>
>No one has yet uncovered the lineage of the highly pathogenic H5N1 strain
>now endemic in Asia. Presumably, it evolved from a low-pathogenicity H5N1
>variant circulating in waterfowl in southern China before the first known
>outbreak of the disease in chickens in Hong Kong in 1997. By culling all
>1.5 million domestic poultry in Hong Kong, authorities stamped out the
>outbreak. With a few exceptions, the virus was not seen again until
>December 2003, when a massive outbreak swept chicken farms in Korea. By
>January, the virus had turned up on farms in Japan and Vietnam; by February
>it was detected in Indonesia, and it was soon killing chickens in Thailand
>and China.
>
>When public health experts pointed to migratory birds as a likely source,
>ornithologists and animal epidemiologists showed that the outbreaks did not
>neatly fit any known migratory patterns. If migratory birds were carriers,
>they argued, the virus should have turned up in the Philippines and Taiwan
>by now, but it hasn't. What's more, since the late 1990s, USDA has sampled
>more than 10,000 waterfowl crossing the Bering Sea from Asia to Alaska,
>while University of Hong Kong researchers have tested several thousand
>entering Hong Kong; neither group has found a single healthy bird carrying
>the H5N1 virus.
>
>Instead, human movements of infected poultry have spread the virus over
>seemingly improbable distances. For instance, an outbreak of H5N1 among
>poultry in Lhasa, Tibet, in January 2004 was traced to a shipment of
>chickens from Lanzhou in China's Gansu Province, about 1500 kilometers
>away. An even more bizarre case surfaced in October 2004, when an air
>traveler was caught at Brussels Airport with two crested hawk eagles,
>infected with H5N1, in his carry-on bag. The smuggler had bought them at a
>Bangkok bird market on behalf of a Belgian falconer.
>
>A new paradigm
>As the epidemic continues, it's becoming increasingly clear that H5N1
>represents a "change in the paradigm" of what is known about avian
>influenza viruses, says Les Sims, a veterinarian in Manunda, Australia.
>Before this strain of H5N1 appeared, for instance, waterfowl were thought
>to be resistant to infection by highly pathogenic viruses. Studies over the
>last several years have shown that domestic ducks can asymptomatically
>carry some strains of H5N1 that are lethal to chickens. (Yet other H5N1
>strains are lethal to domestic ducks.)
>
>Until last spring, however, there was no sign that H5N1 was infecting any
>wild birds in a significant way. That changed in April, when an H5N1
>outbreak at Lake Qinghai in northwestern China killed an estimated 5000 to
>6000 migratory water birds.
>
>The die-off immediately raised alarms that surviving birds might carry the
>virus to India and beyond. But, apparently because of infighting between
>Chinese ministries and institutions, the government barred Chinese and
>outside scientists from sampling or tracking the travel of surviving birds.
>"It was a missed opportunity," says ornithologist David Melville from
>Nelson, New Zealand.
>
>
>
>Researchers are still wondering how the virus got to this remote corner of
>China. Just after the Lake Qinghai outbreak, the virus turned up on a
>poultry farm in the same province. This "makes it difficult to tell whether
>poultry or wild birds brought the virus to the area," says Suarez.
>An August outbreak at Erkhel Lake in Mongolia, however, helped persuade
>Sims that wild birds are to blame, but his change of mind comes not from
>finding a positive link but from ruling out human movements of poultry, he
>warns. "All epidemiology is based on probabilities," he adds.
>
>A group of veterinarians from the Wildlife Conservation Society was already
>in Mongolia in case H5N1 made the 600-kilometer leap when it heard of
>unusual bird deaths at Erkhel Lake. The group collected 774 samples from
>both dead and living birds. USDA confirmed highly pathogenic H5N1 in dead
>birds--but found no evidence of the virus in any samples from the live
>ducks, gulls, geese, or swans.
>
>Because there are so few poultry in this isolated region, Suarez thinks
>their involvement is "unlikely." "The most likely scenario," he says, is
>that wild birds carried the virus to Erkhel Lake and infected the birds
>that eventually died. "We don't know which species were responsible for
>spreading the virus," says Sims, who is also involved in the project,
>although he suspects that those unidentified species could be spreading the
>virus elsewhere. (The researchers declined to provide further details
>because they are readying an article for publication.) Figuring out which
>species might be involved will be tough, others note, as next to nothing is
>known about avian influenza except in waterfowl.
>
>Searching
>Some answers may come from Fu-Min Lei, an ornithologist at the Institute of
>Zoology in Beijing, part of the Chinese Academy of Sciences (CAS). Since
>last March, he has collected more than 6000 viral and serological samples
>from a variety of wild animals throughout China, including 2000 samples
>from migratory and resident birds, and is searching for H5N1.
>
>Another Chinese team led by George Gao, a virologist at CAS's Institute of
>Microbiology in Beijing, has collected several dozen serum samples from
>birds that survived the H5N1 outbreak at Qinghai Lake. If any test positive
>for antibodies to the H5N1 virus, says Gao, who is preparing to publish a
>paper, it would suggest that some mildly infected water birds might be
>carrying the virus long distances.
>
>Even before the virus turned up in Turkey, the incidents at Qinghai and
>Erkhel and the spread of the H5N1 virus through Siberia and Kazakhstan had
>sparked new surveillance efforts. In Europe, Albert Osterhaus, a virologist
>at Erasmus University in Rotterdam, the Netherlands, has proposed a
>Europe-wide wild bird surveillance program. His group currently gathers
>cloacal samples from 6000 birds annually, primarily in the Netherlands (see
>sidebar). Extending such surveillance to critical migratory routes crossing
>Europe, which he estimates would cost about $2.5 million, would not only
>serve as an early warning system for a possible pandemic, he says, but also
>provide data on other viruses that pose a threat to domestic flocks.
>Osterhaus would like to see similar networks set up to cover flyways in
>Asia-Pacific and the Americas.
>
>Other nations have not recognized the need, so surveillance is patchy,
>except in Asia, which has an aggressive program of sampling wild birds and
>birds brought to live poultry markets.
>
>The United Nations Food and Agriculture Organization (FAO) is helping
>nascent surveillance efforts in South Asia, and the World Organisation for
>Animal Health recently sent an expert mission to support surveillance in
>Russia. "We're very concerned about India and Bangladesh," says FAO's Juan
>Lubroth, because the bar-headed geese that breed at China's Qinghai Lake
>winter in South Asia. But Lubroth notes that wild bird surveillance is just
>one on a long list of veterinary needs that includes strengthening local
>lab capabilities and improving hygiene on farms and in markets. All these
>measures are desirable no matter how H5N1 is being spread, he says. FAO has
>appealed to the international community for $100 million to fight avian
>influenza in Asia but has so far only raised $30 million--a small sum,
>Lubroth says, for trying to avert a human pandemic.

--
Dennis Paulson, Director Emeritus phone 253-879-3798
Slater Museum of Natural History fax 253-879-3352
University of Puget Sound e-mail dpaulson at ups.edu
1500 N. Warner, #1088
Tacoma, WA 98416-1088
http://www.ups.edu/biology/museum/museum.html