Creeping north with the spring migration of waterfowl, a highly contagious form of bird flu visited Missouri and Kansas before dooming millions of hens recently at an Iowa egg facility.
Last week the governors of Wisconsin and Minnesota declared states of emergency.
And come autumn, scientists say, outbreaks of avian influenza probably will circle back, killing more commercial poultry in its path.
Experts already are calling it the worst U.S. outbreak of bird flu in more than three decades.
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The strain known as H5N2, which rarely is passed to humans, was found in early March at a southwest Missouri farm holding more than 15,000 turkeys. Soon the virus fired up in another turkey farm in central Missouri’s Moniteau County.
By the middle of March, a small flock of backyard chickens and ducks tested positive near Basehor in Leavenworth County, Kan.
In each case, state agriculture and local emergency crews set up quarantine zones, knocked on doors in a 3-mile radius of where the flu hit, swabbed the beaks of poultry in the area and destroyed infected birds.
Around Basehor they instructed feed stores to hold off selling Easter chicks. The tiny chirpers had to be certified as having come from outside the area before people could buy them.
Still, H5N2 would not be halted. As ducks and geese flapped northward, unaffected by the virus they carried, their droppings across eight Midwest states scattered seeds of a pathogen deadly to commercial poultry, especially turkeys.
“What we’re seeing is very unusual in the sense it’s moving through waterfowl and, really, moving throughout the world,” said USDA chief veterinary officer John Clifford in a conference call to reporters last week.
“We’re likely to see additional cases in the fall” when wild birds migrate south from Canada, he said, and maybe for years to come.
Human risk low
After a large egg operation in northwest Iowa last week confirmed the virus racing through a facility of nearly 4 million chickens, Clifford and others monitoring outbreaks stressed the public health risk is considered low.
No human infections have been detected during the U.S. outbreaks, USDA said.
The sick chickens in Iowa are being euthanized with a foam that knocks them out in seconds. Their eggs, which were to be processed by South Dakota-based Sonstegard Foods Co., are being kept out of the food supply, officials said.
If any infected poultry products slip past inspectors, heat will kill H5N2 and more common pathogens such as salmonella, lessening the threat for consumers.
“You cook it out of them,” said Kyoung Jin Yoon of Iowa State University’s College of Veterinary Medicine.
Likewise, a stretch of several warm days with highs in the 70s should bring a region’s outbreaks to a lull, Clifford said: “This virus doesn’t like heat very much at all.”
That’s why the H5N2 crisis appears to have been stamped out for now in states such as Arkansas, Missouri and Kansas. It’s gaining steam in the northern reaches of Iowa, in Minnesota and the Dakotas, where recent daily temperatures haven’t often exceeded 60 degrees.
Once infected, poultry typically die within 48 hours. The death rate among turkey flocks is close to 100 percent. Exposed chickens have a survival rate of about 40 percent, scientists say.
The financial threat to turkey growers in Wisconsin is severe enough that Gov. Scott Walker last week authorized the state’s National Guard to assist in the response to bird flu confirmed in three counties.
Minnesota Gov. Mark Dayton declared a state of emergency Thursday.
Although the potential impact on U.S. poultry prices is unclear, foreign countries already have placed restrictions on American poultry exports.
The virus surfaced in late 2014 in what the USDA called “backyard flocks” of wild birds in Oregon, Idaho and Washington state, along the Pacific flyway’s migratory path.
Authorities don’t puzzle much over how H5N2 hits small, random flocks often around remote ponds. Migratory fowl are drawn to bodies of water where they’ll leave infected droppings before heading on, putting other birds in the area at risk.
It’s a mystery, though, how the virus finds its way into enclosed hatcheries and commercial poultry squeezed into barns.
Has it traveled on feathers blown by the wind? Or on rodents and barnyard cats with bird poop in their fur?
Experts say even humans can transport H5N2 by way of soiled boots or the trucks they drive.
“If you’re out hunting and your dog’s running through the fields before jumping back in the truck, you’ve just brought it (the virus) home,” said Scott Beyer, a poultry specialist with K-State Research and Extension.
For this reason the Kansas State University students doing research in the school’s poultry unit enter through a single door, stamp their shoes on a mat saturated in disinfectant and change clothes before and after handling the chickens.
Such precautions have long been part of the poultry unit’s biosecurity protocol, Beyer said, but “I’m sure right now they’re double-checking all of that…
“During a time like this, it’s best for a poultry grower to be as isolated as possible. They’ll stay home and not mix with other growers. Some don’t even go to the coffee shop. One told me, ‘I won’t sit in the same pew at church with another poultry grower.’”
The signs of a sick turkey are similar to symptoms in humans leveled by the flu.
They cough, wheeze, hang their heads and look sluggish.
A seasoned poultry farmer can spot it in an instant, said Kelly Smith, marketing and commodities director for the Missouri Farm Bureau.
“If you’ve raised turkeys for years and years,” he said, “you know how a normal turkey acts. They’re like your own children. When you’re around them you know when they feel good and don’t.”
Strangely, the waterfowl thought to be carrying H5N2 up into the Midwest and cooler climes beyond seem to be unfazed by the effects of the virus.
“If it were killing ducks that would actually help” because the flu strain wouldn’t travel so far or persist for months, said Beyer of K-State.
U.S. protocols for preventing, finding and eradicating poultry disease are said to be the most stringent in the world. After the backyard flock of hobby chickens started dying west of Basehor, about 20 state workers converged at a township fire station to huddle with Leavenworth County emergency management staff.
They pored over aerial maps. They dispatched survey teams to identify properties where waterfowl might mingle with wild turkeys and backyard chickens.
Chuck Magaha, emergency management director for the county, said the office’s Facebook alerts on the bird flu threat drew 13,500 hits.
“I was amazed at how many backyard flocks were within the the containment site” spanning 10 kilometers (about 6 miles), he said. “Well over 100 of them. Wow, I had not a clue.”
A week of taking swab samples of birds yielded no other positive findings of the virus. Of the flock found to be infected near Basehor, 10 birds died of the flu or were euthanized, according to the USDA.
Authorities say the general public can play a role in preventing the spread of H5N2 by avoiding places where ducks and geese gather, or by changing clothes and cleaning shoes after being in close contact with watherfowl and commercial poultry.
“When you see a duck out there,” said USDA’s Clifford, “you’ve got to think about the possibility of it being infected.”