Avian influenza showed up in Minnesota this year about 10 days later than last year, and experts say cases across the country are also growing at a slower rate this year.
One reason for that might be later than normal snow and ice delaying the early spring migration.
“They seem to be kind of held out at the snow line,” said Julianna Lenoch. National Coordinator for the USDA APHIS National Wildlife Disease Program. “We've got some pretty spectacular videos coming in of snow geese and some other species that are just sort of stacking up in Nebraska because they can't get any further north right now.”
But those early migrating geese aren't considered the prime carriers of the highly pathogenic H5N1 virus.
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“It's those dabblers, your mallards, your pin tails, your blue winged, teal and green winged teal, those really seem to be the movers and shakers of this virus,” said Bryan Richards, emerging disease coordinator with the US Geological Survey National Wildlife Health Center.
What’s on the way?
As those dabbling ducks migrated to Central and South America last fall there were corresponding new outbreaks of avian influenza in many countries. That means the virus remained active and widespread.
“But the big question right now is what do our dabbling ducks bring back north with them? I think that's a really important question that will be answered very clearly over the course of the next six, eight weeks, something like that, as those dabblers head north,” said Richards. “If they're infected, if they're shedding virus, we'll know about it."
Richards will be watching for outbreaks in back yard poultry flocks as the first indicator of how prevalent and virulent the virus is this year. He encourages owners of backyard flocks to have a plan to protect their birds from exposure to wild birds.
Researchers with the U.S. Department of Agriculture have been tracking the virus in Central and South America.
Lenoch said it’s unclear if birds are adapting to the virus.
“And that's really the kind of bang-for-the-buck question. What are they going to bring back with them? And are we going to see any possible immunity?” she said.
The adult birds might have some immunity to the virus but could still spread it.
And wild ducks hatched this spring will be more vulnerable to the virus, perhaps helping to keep the outbreak going.
Watching for a changing virus
Lenoch will be paying close attention to the effect on wild birds.
“One of the big things is watching for any changes in wild bird morbidity and mortality,” she said. “So, are we going to see any large scale deaths or die offs in our wild bird populations.”
Lenoch will also be closely watching reported cases in mammals. There's no national surveillance program to track the disease in mammals, she said, but states test possible cases.
USDA reported several red foxes and a skunk died from avian influenza last year in Minnesota.
Researchers are monitoring DNA changes in the virus found in mammals.
“To keep a very, very close eye on any of those sequence changes that might indicate that the virus is any more dangerous to mammal populations. We really want to be watching that very closely,” said Lenoch.
USDA will continue collecting DNA samples to help monitor the spread and any changes in the virus, always looking for connections.
“So if a Mallard in say South Dakota, comes in and we do the sequence on it and then two or three weeks later we get a sick or dead fox or coyote, they'll compare the genetics of that animal to see how closely it matches," said Lenoch.
While it is helpful for the public to report sick or dead animals such as fox, skunks or coyotes, Lenoch said people should be cautious around sick or dead animals. Avian influenza in mammals can mimic symptoms of rabies or distemper.
“We don't want any accidental exposure to any of the diseases. But particularly rabies is a very high concern because that is such a risk for human exposure. So if the general public were to see a sick animal, please don't touch it but, but call your local animal Control or Department of Natural Resources,” Lenoch said.
What’s next for this virus?
An avian virus moving to mammals brings it a step closer to being able to jump to humans. But the Centers for Disease Control and Prevention says the risk to humans is still low. There have been 11 humans cases worldwide since January of 2022. All were in people who handled infected poultry.
Bryan Richards has looked at cases of avian influenza in mammals and sees no evidence yet the virus is moving from animal to animal.
“It looks like each one of these likely literally had a really bad last meal,” he explained. “They consumed the carcass of another animal, likely an avian, a bird that died from high path AI (avian influenza).”
Lenoch and Richards both expect the virus to be strong again this year.
The waterfowl that carry the virus might be the best hope for slowing it. Waterfowl carry low pathogenic viruses that cause no illness. Richards says those common viruses will eventually mix with the virulent H5N1.
“And so over time, we would anticipate that our low path viruses may overwhelm this highly pathogenic virus. And that's kind of our long term ticket out of this thing.”
That’s what happened in the last big avian influenza outbreak in 2014-2015, said Richards.
But he’s not making any predictions on how long it will take that to happen during this outbreak, and there's no evidence yet that the virus is losing strength.
After more than 4 million bird deaths in Minnesota last year from avian flu, poultry farmers say they're working hard to avoid an outbreak, but also adjusting to living with the virus' presence.
Avian flu hit Pete Klaphake's central Minnesota turkey growing operation hard last year. In one just week, one of his farms tested positive on Monday, another on Tuesday. Within two days, they'd lost more than 100,000 birds.
“After you have a positive, you go through, ‘OK, where can where would we have had a breach?’” he said. “Did we do something, or did something happen?”
Klaphake doesn't have any clear answers. Maybe there was a breach in biosecurity, or the virus simply blew into his barns on a windy day.
“By nature, I'm an eternal optimist,” he said. “So I'm hoping for our industry, I'm hoping for our operation, I'm hoping for the growers that work with us raising birds, that we don't have to deal with anything like we did last year.”
The Minnesota Board of Animal Health’s April 3 announcement of the first new case of bird flu in four months was news that poultry producers have been dreading.
“We have definitely enjoyed kind of the lull in hyperactivity since December, but it doesn't mean that anybody's actually relaxed,” said Ashley Kohls, executive director of the Minnesota Turkey Growers Association. “Folks have definitely remained kind of on the edge of their seats.”
While many Minnesotans are eagerly awaiting spring to melt the snow and ice, poultry producers are nervous for the warmer days that will bring migratory birds north, Kohls said.
Those wild birds can carry the virus to commercial poultry flocks, where it spreads quickly and is almost always lethal. The entire flock must be euthanized to prevent more infections.
Dr. Jill Nezworski, an independent poultry veterinarian, said the poultry industry is moving into a new normal, which includes living with high-path avian flu.
“There's not a lot of optimism,” she said. “Everybody has the sense of impending dread of waiting for the outbreak.”
The industry learned from last year's outbreak, Nezworski said. Farmers stuck to biosecurity plans to prevent the disease from spreading from farm to farm, such as limiting visitors, and sanitizing trucks and equipment.
But Nezworski said data show the majority of outbreaks last year appear to have been so-called independent introductions. So, more than ever, farmers are looking at how to prevent the virus from entering the barn from outside, she said.
“We're all taught how to prevent farm-to-farm spread. That's much more traditional biosecurity practices,” Nezworski said. “In this new normal, we have to get really creative.”
Some poultry farmers are applying calcium chloride to gravel roads, to reduce dust that might blow into barns, she said. Others are taking extreme measures to keep away wild birds that could carry disease. That includes installing systems that scare them away by shining laser beams.
Nezworski said others are trying air horns, fake coyotes, or even giant inflatable air dancers with flailing arms commonly seen at car dealerships.
“I have one grower who's got a stack of bottle rockets that he's shooting off to scare the geese away,” she said.
Other producers say they're not rushing to adopt any new prevention methods, but are sticking to practices that have worked in the past. That includes Erica Sawatzke, a sixth-generation turkey farmer in Kensington, west of Alexandria.
“We've always tried to be diligent about keeping wild birds away, even rodents out of our barn, because they'll track in diseases,” Sawatzke said. “So for us, that's something that we've never changed on our farm.”
Federal scientists have been working on a poultry vaccine to prevent bird flu. But there's still debate over how and when it might be used, driven in part by fears of trade restrictions that it could hurt poultry exports. In any case, mass vaccinations are unlikely to happen in time to prevent an outbreak this year.
Despite the stress and financial strain that avian flu brings, many poultry growers say they’re not thinking of calling it quits. But learning to deal with the threat of a contagious virus is now part of the job.
“I would expect that there's some producers that are nervous,” Sawatzke said. “But I think probably there are some that are realistic, too, and that this is something that we're going to have to learn to live with.”
Klaphake said they're not letting down their guard, and are doing what they can to prevent an outbreak. He tries not to spend too much time dwelling on the what-ifs.
“If you're constantly worrying about about disaster happening in any walk of life, you're not going to do that occupation very long,” he said.