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.
“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.
Source: mprnews.org
Photo Credit: GettyImages-wikoski
Categories: Minnesota, Livestock, Poultry