High pathogenic avian flu hits U.S. through backyard flocks

Outbreaks throughout the Northwest

BELLINGHAM, Washington––Backyard poultry have become an incubator for high pathogenic strains of avian influenza throughout the Pacific Northwest, with recent outbreaks occurring from the Fraser Valley of British Columbia to northern California, and as far east as Idaho.

The Oregon Department of Agriculture and the USDA Animal & Plant Health Inspection Service were as of February 13, 2015 “responding to a detection of highly pathogenic avian influenza (HPAI) in a flock of backyard birds near Tumalo in Deschutes County,” reported MyCentralOregon.com.

The agencies were “in the process of setting up a quarantine zone around the property to restrict movement of domestic birds in and out of the area,” MyCentralOregon.com said. “Currently, the property is secured and there have been no additional detections of HPAI in the area.”

“The flock of about 90 mixed poultry and other domestic birds includes chickens, ducks, and turkeys who have had access to a couple of ponds on the property that are also frequented by migratory wild waterfowl,” MyCentralOregon.com added.

International response

The outbreak was the second known to have occurred in Oregon, following the December 2014 discovery of HPAI H5N8 among guinea fowl and chickens in a backyard flock in Winston, Douglas County. HPAI strains have also been discovered in backyard flocks in Benton, Clallam, and Whatcom counties in Washington, and Canyon County, Idaho.

China on January 16, 2015 prohibited imports of any U.S. poultry shipped after January 9. The 28-nation European Union on January 19, 2015 banned poultry products from Douglas County, Oregon and the entire states of Idaho and Washington. Japan and Belarus, already banning poultry from Oregon and Washington, added Idaho to the list.

Rock Creek Farms, a commercial hatchery in Bellingham, Washington, on January 9, 2015 killed 22,000 healthy chicks because the Canadian Food Inspection Agency had suspended poultry imports from Washington two days earlier.

“Rock Creek Farms had no way to feed or water the chicks,” explained Don Jenkins of the Salem, Oregon Capital Press. “Canadian authorities relaxed the ban on January 13 and allowed 65,000 imperiled chicks to be delivered to a Chilliwack, British Columbia,  poultry farm owned by the same parent company, K&R Poultry.”

“Low risk to public,”  say officials

But the Oregon Department of Agriculture and USDA reassured the public that “The HPAI strains currently detected in Oregon and other states represent a low risk to public health. The virus has not been detected in commercial poultry operations in Oregon, Washington, or Idaho,” the agencies said, adding that “Avian influenza does not affect poultry meat or egg products.”

Though epidemiologists specializing in zoonotic disease tend to agree that isolated local findings of HPAI do not call for panic responses, there is also general agreement that the rapidly increasing frequency of isolated local HPAI discoveries in the Pacific Northwest is a worrisome trend.

Some HPAI strains are much more dangerous than others. Some rapidly mutate. Occasionally an HPAI strain jumps from birds to mammals, including humans, and wreaks havoc.

Less than two weeks ahead of the most recent Oregon HPAI discovery, the Canadian Food Inspection Agency “confirmed the presence of a high pathogenic H5N1 avian influenza virus on a non-commercial farm in Chilliwack, British Columbia,” reported The Poultry Site.

This was after 245,600 birds at eleven infected British Columbia poultry farms were culled during the first 16 days of December 2014 to try to stop outbreaks of low pathogenicity avian influenza (LPAI).

The flu with a 55% death rate

Farmers and public health agencies have fought repeated outbreaks of avian flu in Fraser River drainage basin of British Columbia for at least eleven years.

But H5N1, the avian flu with the highest death rate among infected humans, was never before involved. Many other flu strains pass more easily to humans, and therefore afflict and kill far greater numbers, but the overwhelming majority of humans quickly recover from most flus, whereas the death rate from H5N1 runs as high as 55% worldwide.

Affirmed The Poultry Site, “This is the first time the H5N1 strain of the virus has been detected in the Fraser Valley. The other affected farms in British Columbia were infected by the H5N2 strain,” also of concern to the poultry industry, but without a history of causing deadly disease in humans.

First detected in Hong Kong in 1996, H5N1 avian flu has now killed more than 400 people in 16 nations, chiefly in Indonesia, Egypt, Vietnam, and China. The first North American H5N1 fatality died in Alberta, Canada, in January 2013, a month after traveling in China. At the time, any H5N1 cases occurring in North America were presumed to have resulted from foreign exposure. That assumption can no longer be made.

H5N1 found in teal

The H5N1 strain was also found in wild birds in Washington state in January 2015.

Announced the National Wildlife Health Center, a branch of the U.S. Geological Survey, “A novel H5N1-reassortant virus was identified from a green-winged teal sampled through hunter-harvest surveillance. Scientists from NWHC sampled this bird in Whatcom County, Washington on December 29, 2014. The bird from which this novel virus was identified originated in the same general area of Whatcom County where other [related] HPAI viruses have been identified, indicating that this group of viruses continues to circulate in North American wild birds.

“It is important to note,” the National Wildlife Health Center said, “that the H5N1 virus recently detected in Washington is different from the Asian strain of H5N1. Specifically, the USDA’s National Veterinary Service Laboratories determined that it is a reassortant, or mixed-origin, virus that incorporates Asian-origin genes from the H5N8 virus,” another HPAI strain, “recently detected in a captive gyrfalcon (Washington) and waterfowl (California, Idaho, and Utah), together with other genes from a low-pathogenic avian influenza virus of North American wild-bird origin.”

Pacific flyway

The Pacific flyway, the migratory bird path running from Alaska down the Pacific coast between the western Cascades and the ocean, overlaps in the Arctic Circle with the East Asian-Australasian Flyway, “so birds who winter in Cambodia might roost next to birds who winter in California,” Adam Cotterell of Boise State Public Radio explained to listeners on February 9, 2015.

Affirmed Idaho Fish & Game ornithologist Jeff Knetter. “There are a variety of species that co-mingle along the Bering Strait, northern Alaska, and even northern Russia. Those could be snow geese, northern pintail, mallards, green winged teal, American wigeon––all species that you can see in the Treasure Valley” of western Idaho and eastern Oregon.

Snow geese, for example, are known to spend their summers on Wrangle Island and in Russia, and winter in the Central Valley of California, stopping over in southwestern Idaho on their migrations north and south. Knetter estimated that the annual migrations through Idaho involve 50,000 to 60,000 snow geese and 30,000 to 40, 000 greater white fronted geese.

“Ten to 15 years ago, neither of these species passed through Idaho,” Cotterell said. “But their migration patterns have changed,” possibly due to effects of global warming.

Stepping in poop

Acknowledged Idaho state veterinarian Bill Barton, “With the migratory routes of wild birds in Asia, and then the migratory routes from Asia over to the U.S., there’s a lot of co-mingling of birds. Among poultry and wild birds, avian influenza is easy to pass from one bird to another.”

Summarized Cotterell, “Bird flu is most commonly transmitted through feces. A migrating bird could easily get the virus by stepping in its Asian neighbor’s waste and later pass it to an Idaho chicken through its own.”

Previously seen mostly in Asia, with deadly outbreaks also occurring in northern Africa and scattered cases in Europe, HPAI strains may have been shed over North America for decades by defecating migratory ducks, geese, and swans. Non-migratory Canada geese might have been vulnerable, along with ornamental ducks, geese, and swans, but these birds have relatively little contact with humans, and until recently the chances of migratory waterfowl infecting North American domestic poultry were minimal.

This is because––unlike in Asia, Africa, and other places where HPAI strains have afflicted humans––in the U.S. and Canada almost all commercially produced poultry are raised entirely indoors. This is more than 99% of all the poultry on the continent.

Backyard poultry explosion

Backyard poultry-keeping, however, has recently exploded from a rarity in urban and suburban areas into a cottage industry of significant size. The U.S. Department of Agriculture estimated that as of 2005, about 138,000 small non-commercial poultry flocks included circa 9.7 million birds.

A decade later, the numbers may have doubled, putting perhaps twice as many domestic chickens, ducks, and geese at risk from infection and in proximity to humans.

If a domestic flock becomes infected, human caretakers may then carry infections from flock to flock on contaminated clothing and shoes. Worse, humans and other animals may incubate mutated forms of HPAI viruses.

From birds to pigs to people

Especially dangerous, historically, are HPAI viruses that mutate in pigs to pass rapidly among other mammals. So-called swine flus that have evolved in pigs to easily infect humans have been responsible for all of the deadliest influenza outbreaks in human history, including the 1918-19, 1957-58, and 1968-69 flu pandemics that killed upward of 30 million people among them.

Each started among the farms and live markets of Guangdong, China, a region featuring vast rice paddies frequented by migratory waterfowl, where domestic birds have traditionally been kept in cages above pig pens, enabling pigs to consume the undigested grain in their feces.

Each afflicted pigs first, but attacked humans within a few months, then spread rapidly from person to person.
The H5N1 avian flu strain was first identified after it killed a three-year-old boy in Hong Kong on May 21, 1997, but the disease is believed to have reached Hong Kong with infected poultry from Guangdong, just to the north. Hong Kong civil servants in 1997-1998 killed more than 3.5 million poultry to try to eradicate H5N1, but it reappeared in 2003, hitting the Middle East and Africa in 2006.

How LPAI becomes HPAI

All influenzas originate in birds as low pathogenicity virus that mutate into more dangerous forms.

Explained Program for Monitoring Emerging Diseases (ProMED-mail) wildlife disease moderator Pablo Beldominico in a recent posting about the Pacific Northwest outbreaks, “Aquatic wild birds are the natural reservoirs of low pathogenicity avian influenza viruses (LPAI). Before the emergence of the highly pathogenic H5N1 strain [in Asia] almost a decade ago, the general rule was that low pathogenicity avian influenza could mutate into high pathogenicity strains when infecting domestic fowl, generating outbreaks that were always associated with domestic birds.”

Wild birds were believed to be unlikely to carry HPAI strains very far, if at all, because severely sick birds die and dead birds do not migrate.

“Wild bird deaths [from HPAI strains] were restricted to birds in the vicinity of affected farms,” Beldominico continued. “It is thought that Asian high pathogenic H5N1 is found in a very small number of species in which it could be perpetuated. These species would suffer long subclinical viremia,” meaning that they might be mildly ill for months, but not so ill as to be unable to fly.

HPAI H5N2

The Asian strain of H5N1 “is still there causing troubles, but it never reached the Americas,” Beldominico summarized.

However, continued Beldominico, “Early in 2014, a new high pathogenicity strain of avian flu with similar ability to propagate globally appeared: HPAI H5N2. In November 2014, it reached Europe,” Beldominico said, “and on December 16, 2014 it was found in the U.S.”

HPAI H5N2 is a deadlier version of the more familiar LPAI H5N2, identified during a 1983 outbreak among chickens and turkeys in Maryland, but also continuing to spread worldwide despite more than 30 years of attempts to eradicate it through vaccination and killing whole infected flocks.

The LPAI H5N2 strain, for example, on December 3, 2014 appeared for the first time in Spanish Lookout, Belize, in Central America. How it reached Belize is unknown, but Spanish Lookout is a major poultry production area, and harbors a cockfighting industry. Cockfighters moving gamefowl have been the major mechanism for spreading H5N1 in Southeast Asia, especially in Indonesia, and may have been involved in the Belize outbreak.

LPAI H5N2 is not believed to be capable of easily mutating by itself into HPAI H5N2, but the global distribution of LPAI H5N2 may indicate where HPAI H5N2 may follow if conditions permit––and HPAI H5N8 as well.

“An H5N2 high pathogenicity strain of the virus was identified in a wild northern pintail in the same county of Washington state in the U.S. as the first case of H5N8,” Beldominico noted.

Caldron in the Arctic

Simply put, the evidence suggests that migratory waterfowl meeting each summer within the Arctic Circle are not only exchanging flu infections indigenous to themselves and then spreading them south in the winter, but are also now bringing mutated versions of avian flu back to the Arctic Circle with them, and then sharing them around the world.

Carroll Cox, founder of the Hawaii-based organization EnviroWatch, outlined this scenario to media and ProMed on December 31, 1997. Cox predicted that when H5N1 hit the U.S. it might as likely come through migratory waterfowl shot by sport hunters as through any commerce in domestic poultry or poultry products.

Almost 17 years to the day later, the green-winged teal shot in Whatcom County, Washington proved Cox was correct in his assessment. Two days later, on December 31, 2014, the USDA confirmed that a hunter-shot duck in Butte County, California was infected with HPAI H5N8.

While authorities remained confident that HPAI outbreaks could not spread to humans through consuming infected waterfowl or poultry, a captive falcon who had been fed a hunter-shot duck reportedly died of avian flu of some sort in Whatcom County.

Then, on January 20, 2015, Idaho state veterinarian Bill Barton disclosed to media that HPAI H5N2 had been found among both falcons and a small non-commercial flock of chickens in in Canyon County.  The three falcons confirmed to have had the virus had been fed hunter-shot ducks,  Barton said.

Barton also disclosed that wild ducks infected with H5N8 avian influenza had been found in Gooding County, Idaho.

“Barton said he knew of no other case of highly pathogenic bird flu ever in Idaho,”  reported Dan Jenkins of the Capital Press.  “A less contagious strain of low pathogenic avian flu was found in a southwestern Idaho game bird farm in 2008.”

Moving HPAI around

Though wild birds appear to have introduced HPAI to the Pacific Northwest, keepers of non-commercial poultry flocks may also be implicated in moving the HPAI strains around.

For example, the Washington State Department of Agriculture on January 18, 2015 killed a multi-species 118-bird non-commercial flock in Port Angeles, Clallam County, on the Olympic peninsula.

The birds’ owner contacted the WSDA after a Sebastopol goose died and several chickens fell ill. The WSDA learned that the owner recently sold birds who were subsequently introduced to a flock in Neah Bay, also in Clallam County. However, birds in Neah Bay flock tested negative for avian influenzas.

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