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<TABLE cellPadding=8 width="100%" border=0><TBODY><TR><TD class=articleDate>http://www.insidebayarea.com/sanmate...ews/ci_3811231
Article Last Updated: 5/11/2006 11:28 AM
</TD></TR><TR><TD height=5></TD></TR><TR><TD class=articleOverline></TD></TR><TR><TD class=articleTitle>Is avian flu headed to California?</TD></TR><TR><TD class=articleSubTitle>Infected birds don't mean imminent pandemic, experts say</TD></TR><TR><TD class=articleByline>Suzanne Bohan, STAFF WRITER
Inside Bay Area</TD></TR><TR><TD height=10></TD></TR><TR><TD class=articleBody>MEET H5N1. It's an avian influenza virus spreading worldwide dread that may be winging its way to a marsh near you.
Migratory birds infected with H5N1 are expected to arrive this fall in the United States, heading down the West Coast along the Pacific Flyway, according to the U.S. Department of the Interior. Some of these birds will stop for the winter in Central Valley waterways, or in marshlands ringing the San Francisco Bay or lining the Northern California coastline.
This microscopic speck engenders nightmarish scenarios of death and misery. International health experts warn of a pandemic causing between 100 million and 150 million deaths worldwide, along with an economic meltdown, if H5N1 manages to mutate into a form easily passed from one human to another.
See, right now, it doesn't do that. Nor, for that matter, may it ever be able to do it.
It begs the question: With H5N1 as a potential neighbor in nearby waterfowl, is it time for high anxiety? Or at least concern?
No to the first, and maybe to the second, in the view of some experts in communicable diseases.
"Even though it s important to be concerned," said Dr. Lee Riley, an infectious disease specialist with UC Berkeley's School of Public Health, "this alarm about the pending pandemic may be unjustified, given what we know about influenza pandemics."
He pointed out that in the history of humanity, there have only been three recorded pandemics: the Spanish flu in 1918, the Asian flu in 1957 and the Hong Kong flu in 1968. He doesn t believe that flu pandemics necessarily follow a cycle, or that we're overdue for another. Discussions of bird flu often reference the statistic that about every five decades a flu pandemic arises, but Lee noted that accounts for only the past century, not the long arc of human history.
So Riley ? and he's not alone ? thinks a pandemic from H5N1 is far from imminent.
"This is not new, this kind of concern," Riley added, commenting that there were similar reactions to the 2003 SARS outbreak. Yet it didn't flare into the feared outcome; instead, the microbe causing it retreated.
Moreover, he believes that the rigorous efforts under way now to control the spread of H5N1 may be succeeding in doing just that. Those efforts include the ongoing eradication of infected flocks, or those potentially exposed to it. Thus, far more than 200 million birds have been killed by the virus or through eradication. Public health workers are also assiduously monitoring the spread of the germ in domestic and wild fowl, and carefully screening foreign travelers to thwart smuggling of exotic birds.
Robert Friis, Ph.D., author of the 2006 book "Essentials of Environmental Health," which includes an analysis of recent human cases of H5N1, and professor at California State University, Long Beach, discussed varying perspectives on the risk of a bird flu-triggered pandemic.
"There is a minority point of view that this is hype and not merited based on the information we have," he was quoted as saying in a CSU publication. "But the more frequent point of view, and one I think we should take into account, is that it is an event that potentially could be very hazardous."
What's alarming about this virus is that it's far from petering out, at least in birds. A deadly strain of H5N1 in birds first emerged in 1997; it then mutated and re-emerged in 2002 in a more aggressive form. It's since spread throughout Asia and has been detected in Russia, the Middle East, Europe and Africa.
"The concern is we haven't got it under control in bird populations," said Sharon Hietala, a virologist with the University of California, Davis. "There's never been such widespread prevalence of H5N1 in domestic birds."
Ominously, as of May 4, the World Health Organization reports 206 people have been infected with H5N1, primarily those in close contact with infected poultry. And 55 percent, or 113 of them, have died. It's that shockingly high mortality rate that has the world on edge ? that the microbe could mutate into a form that would aggressively infect humans.
The influenza virus is a master of mutation. The fact that it's made from a genetic material called RNA, as opposed to the more stable DNA, accounts for its malleability. Its changeable nature means it could morph itself into a deadly strain that easily spreads from person to person.
Currently, H5N1 is very difficult for humans to catch, because the virus only infects cells deep within the lungs, an area hard to reach for the virus, according to an April 26 article in the Journal of the American Medical Association.
In contrast, typical flu viruses that infect people latch on and infect cells in the upper airway tract, such as the nose, mouth or throat. A few mutations, however, could allow deadly H5N1 strains to infect the upper airway in humans, allowing far easier human-to-human transmission. Those changes triggered the 1918, 1957 and 1968 pandemics.
The greatest threat posed by wild birds carrying H5N1 into California is that they'll infect poultry. Around the state, these birds are found in farms and backyard flocks. The wild birds are believed to be carrying a less virulent form of H5N1 ? there are multiple strains, and only a few are deadly. But if the wild birds infect their domesticated cousins, the virus could mutate into the deadly form in poultry.
Already, scientists at five surveillance laboratories across the state are looking for signs of birds infected with H5N1, said Hietala, although they aren't expected until the fall. Every day, researchers are gathering samples from poultry in farms and backyards, testing for the H5N1 influenza virus.
"If it gets into that population," explained Hietala, "it's going to be really hard to control."
The odds are vanishingly small that wild birds would infect humans directly. But there is a real risk that wild birds could infect the domestic fowl. The virus in the fowl could mutate to a deadly form, as has happened in Asia, and poultry workers would be at risk of avian influenza infection, where it could potentially mutate to a form passed among humans.
A less-frequently-discussed scenario, however, is the potential for the virus, if it does acquire the ability to spread among people, to mutate to a less harmful form.
In an even more hopeful scenario, the deadly H5N1 in birds could simply disappear, as genetic changes in the virus turn it into a new variety altogether.
"The other line of thought is in the natural order of things, it will cycle out," said Hietala. "I think the high-pathogen one will burn itself out if we can control its spread in commercial poultry," she said of the H5N1 strains now wiping out flocks in Asia.
But she's concerned that the less deadly versions of H5N1 could become endemic to wildfowl.
"If it becomes endemic, you're always worried that it's just a few mutations away from becoming deadly to poultry," Hietala said.
Still, in a world where humans live in close quarters with animals ? the sources of many infectious diseases in humans ? the extensive preparations underway for avian flu are good insurance for the ever-present threat of infectious disease, health officials point out.
However, there's a danger in focusing too intently on one microbial menace, while leaving our guard down against others, Hietala warned.
"Everyone is watching the sky for birds infected with influenza," she said. "And we just know that something is going to sneak up from behind, some infectious agent we've never seen before."
Contact Suzanne Bohan at (650) 348-4324 or sbohan@angnewspapers.com.
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Article Last Updated: 5/11/2006 11:28 AM
</TD></TR><TR><TD height=5></TD></TR><TR><TD class=articleOverline></TD></TR><TR><TD class=articleTitle>Is avian flu headed to California?</TD></TR><TR><TD class=articleSubTitle>Infected birds don't mean imminent pandemic, experts say</TD></TR><TR><TD class=articleByline>Suzanne Bohan, STAFF WRITER
Inside Bay Area</TD></TR><TR><TD height=10></TD></TR><TR><TD class=articleBody>MEET H5N1. It's an avian influenza virus spreading worldwide dread that may be winging its way to a marsh near you.
Migratory birds infected with H5N1 are expected to arrive this fall in the United States, heading down the West Coast along the Pacific Flyway, according to the U.S. Department of the Interior. Some of these birds will stop for the winter in Central Valley waterways, or in marshlands ringing the San Francisco Bay or lining the Northern California coastline.
This microscopic speck engenders nightmarish scenarios of death and misery. International health experts warn of a pandemic causing between 100 million and 150 million deaths worldwide, along with an economic meltdown, if H5N1 manages to mutate into a form easily passed from one human to another.
See, right now, it doesn't do that. Nor, for that matter, may it ever be able to do it.
It begs the question: With H5N1 as a potential neighbor in nearby waterfowl, is it time for high anxiety? Or at least concern?
No to the first, and maybe to the second, in the view of some experts in communicable diseases.
"Even though it s important to be concerned," said Dr. Lee Riley, an infectious disease specialist with UC Berkeley's School of Public Health, "this alarm about the pending pandemic may be unjustified, given what we know about influenza pandemics."
He pointed out that in the history of humanity, there have only been three recorded pandemics: the Spanish flu in 1918, the Asian flu in 1957 and the Hong Kong flu in 1968. He doesn t believe that flu pandemics necessarily follow a cycle, or that we're overdue for another. Discussions of bird flu often reference the statistic that about every five decades a flu pandemic arises, but Lee noted that accounts for only the past century, not the long arc of human history.
So Riley ? and he's not alone ? thinks a pandemic from H5N1 is far from imminent.
"This is not new, this kind of concern," Riley added, commenting that there were similar reactions to the 2003 SARS outbreak. Yet it didn't flare into the feared outcome; instead, the microbe causing it retreated.
Moreover, he believes that the rigorous efforts under way now to control the spread of H5N1 may be succeeding in doing just that. Those efforts include the ongoing eradication of infected flocks, or those potentially exposed to it. Thus, far more than 200 million birds have been killed by the virus or through eradication. Public health workers are also assiduously monitoring the spread of the germ in domestic and wild fowl, and carefully screening foreign travelers to thwart smuggling of exotic birds.
Robert Friis, Ph.D., author of the 2006 book "Essentials of Environmental Health," which includes an analysis of recent human cases of H5N1, and professor at California State University, Long Beach, discussed varying perspectives on the risk of a bird flu-triggered pandemic.
"There is a minority point of view that this is hype and not merited based on the information we have," he was quoted as saying in a CSU publication. "But the more frequent point of view, and one I think we should take into account, is that it is an event that potentially could be very hazardous."
What's alarming about this virus is that it's far from petering out, at least in birds. A deadly strain of H5N1 in birds first emerged in 1997; it then mutated and re-emerged in 2002 in a more aggressive form. It's since spread throughout Asia and has been detected in Russia, the Middle East, Europe and Africa.
"The concern is we haven't got it under control in bird populations," said Sharon Hietala, a virologist with the University of California, Davis. "There's never been such widespread prevalence of H5N1 in domestic birds."
Ominously, as of May 4, the World Health Organization reports 206 people have been infected with H5N1, primarily those in close contact with infected poultry. And 55 percent, or 113 of them, have died. It's that shockingly high mortality rate that has the world on edge ? that the microbe could mutate into a form that would aggressively infect humans.
The influenza virus is a master of mutation. The fact that it's made from a genetic material called RNA, as opposed to the more stable DNA, accounts for its malleability. Its changeable nature means it could morph itself into a deadly strain that easily spreads from person to person.
Currently, H5N1 is very difficult for humans to catch, because the virus only infects cells deep within the lungs, an area hard to reach for the virus, according to an April 26 article in the Journal of the American Medical Association.
In contrast, typical flu viruses that infect people latch on and infect cells in the upper airway tract, such as the nose, mouth or throat. A few mutations, however, could allow deadly H5N1 strains to infect the upper airway in humans, allowing far easier human-to-human transmission. Those changes triggered the 1918, 1957 and 1968 pandemics.
The greatest threat posed by wild birds carrying H5N1 into California is that they'll infect poultry. Around the state, these birds are found in farms and backyard flocks. The wild birds are believed to be carrying a less virulent form of H5N1 ? there are multiple strains, and only a few are deadly. But if the wild birds infect their domesticated cousins, the virus could mutate into the deadly form in poultry.
Already, scientists at five surveillance laboratories across the state are looking for signs of birds infected with H5N1, said Hietala, although they aren't expected until the fall. Every day, researchers are gathering samples from poultry in farms and backyards, testing for the H5N1 influenza virus.
"If it gets into that population," explained Hietala, "it's going to be really hard to control."
The odds are vanishingly small that wild birds would infect humans directly. But there is a real risk that wild birds could infect the domestic fowl. The virus in the fowl could mutate to a deadly form, as has happened in Asia, and poultry workers would be at risk of avian influenza infection, where it could potentially mutate to a form passed among humans.
A less-frequently-discussed scenario, however, is the potential for the virus, if it does acquire the ability to spread among people, to mutate to a less harmful form.
In an even more hopeful scenario, the deadly H5N1 in birds could simply disappear, as genetic changes in the virus turn it into a new variety altogether.
"The other line of thought is in the natural order of things, it will cycle out," said Hietala. "I think the high-pathogen one will burn itself out if we can control its spread in commercial poultry," she said of the H5N1 strains now wiping out flocks in Asia.
But she's concerned that the less deadly versions of H5N1 could become endemic to wildfowl.
"If it becomes endemic, you're always worried that it's just a few mutations away from becoming deadly to poultry," Hietala said.
Still, in a world where humans live in close quarters with animals ? the sources of many infectious diseases in humans ? the extensive preparations underway for avian flu are good insurance for the ever-present threat of infectious disease, health officials point out.
However, there's a danger in focusing too intently on one microbial menace, while leaving our guard down against others, Hietala warned.
"Everyone is watching the sky for birds infected with influenza," she said. "And we just know that something is going to sneak up from behind, some infectious agent we've never seen before."
Contact Suzanne Bohan at (650) 348-4324 or sbohan@angnewspapers.com.
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