Happy Nice Mall

There was a problem with the foxes. Callers of the Dane County Humane Society in Wisconsin reported that fox kits or young foxes were behaving in strange ways, they said in April: shaking, grabbing, or trying to stand. Often lethargic and wandering around on their own, he seemed unusually easy to approach and had little fear of humans.

“We just kept getting phone calls,” said Erin Lemley, a wildlife veterinary technician at the Humane Society’s wildlife center. “And the foxes started coming in.”

He said some kits accepted for treatment are quiet and withdrawn. Others stumbled or had seizures, their heads shaking, their eyes twitching rhythmically. After staff has ruled out rabies, low blood sugar, and other possible causes, lab tests revealed surprising culprit: an extremely deadly strain of bird flu.

Zoo and wildlife veterinarian at the University of Wisconsin-Madison, Dr. “It wasn’t a fun surprise,” Shawna Hawkins said.

The virus, a type of avian flu known as Eurasian H5N1, is spreading rapidly in the United States this spring. contamination of farm-raised poultry flocks It led to mass cullings of domestic birds and in 36 states.

But this version of the virus seems to take too much time. more charges on wild birds More than any previous lineage that found its way among ducks, geese, gulls and swallows and others. This means that the virus poses a high threat to mammals that prey on these birds, including wild red foxes.

At least seven US states have detected the virus in red fox kits, where the pathogen appears to be particularly deadly. Two lynxes in Wisconsin, a coyote cub in Michigan, and skunks in canada also tested positive for the virus, foxes, otters, lynx, marten and one badger in Europe. (Two human cases, one in the United States and one in England, reported also, both were in people who had close contact with birds.)

Experts said there is no evidence that mammals play a significant role in the spread of the virus, and the risk to humans remains low. St. in Memphis “It’s still largely an avian virus,” said Richard Webby, a flu virologist at Jude Children’s Research Hospital.

But evolution is a numbers game, and the more mammals the virus infects, the more opportunity it has to pick up new mutations that could help it spread among foxes, lynxes, and even humans, he said.

Dr. “What it takes for this virus to go from being a duck or chicken virus to a mammalian virus is that it has a better chance of replicating in mammalian hosts,” Webby said. “That’s why we come to our attention when we see these mammals infected with this virus.”

twitching foxes

The new strain of the virus spread to Europe, Africa, the Middle East and Asia last year, causing outbreaks in wild and domestic birds. It has also appeared in a handful of wild mammals. fox kits in netherlands in the spring of 2021.

By the end of the year, the virus had made its way to North America. As this spring rapidly swept through the migrating American bird population, reports of infected fox kits began to emerge. Ontario and later in Wisconsin, Minnesota, Michigan, Iowa, Alaska, Utah and new York.

In some bird species, the virus caused obvious neurological symptoms, and many infected foxes also exhibited abnormal behavior. They twitched, walked in circles, and drooled excessively. In the most severe cases, foxes developed seizures; Experts said death usually comes shortly after.

D., a diagnostic pathologist at the Wisconsin Veterinary Diagnostic Laboratory who performed the autopsies. Betsy Elsmo said autopsies revealed that most of the kits had pneumonia. Dr. When Elsmo examined the animals’ brain tissue under a microscope, he saw clear signs of damage.

“Microscopically, there was a lot of inflammation in the brain,” he said. “The injury pattern I saw was consistent with a viral lesion.”

So far the virus seems to be doing more harm to fox kits than adult foxes, potentially because young animals don’t have fully developed immune systems yet, experts say.

However, the overall infection and mortality rate is unknown. “We’re getting kind of anecdotal reports in nature right now,” said Michelle Carstensen, head of the wildlife health program for the Minnesota Department of Natural Resources.

Wisconsin officials also detected the virus in two adult lynxes this spring. Wildlife veterinarian for the Wisconsin Department of Natural Resources, Dr. “Both lynxes showed reduced fear of humans,” Lindsey Long said in an email. “They have been recorded sitting on patios and being close to human activities without the usual fear response.”

He added that while one lynx appeared to be shaking, the other was having trouble breathing. Dr. The euthanized bobcats have microscopic brain lesions that are “almost the same” as those in affected foxes, Elsmo said.

Wildlife veterinarian at the state’s Department of Natural Resources, Dr. Megan Moriarty said that the virus was also recently detected in a coyote puppy in Michigan.

Scientists suspect that the animals acquired the virus by eating infected birds. Inside lab workResearchers have previously shown that red foxes that feed on infected bird carcasses can contract the virus and then spread it.

While it’s possible that the virus may have evolved in ways that made mammals better at infecting, the scientists say the most likely explanation for the spike in infected mammals is that this lineage was infecting large numbers of wild birds, making it more likely to be infected by predators. and scavengers may stumble upon infected food sources.

So far, the virus doesn’t appear to have caused enough illness or death in wild mammals to put this species at risk, experts say. And there is no evidence of sustained mammal-to-mammal transmission. Dr. “Mammals are often considered dead-ends for highly pathogenic avian flu,” Moriarty said.

An early analysis of viral genomes from Wisconsin fox kits shows that the infections were essentially a one-off sequence – the result of individual foxes coming into contact with infected birds rather than foxes infecting each other. Dr. “Our preliminary data suggest that these are all independent spillover events,” Elsmo said.

But much remains unknown, including whether the virus will manifest itself in long-distance wild birds, which could pose a continuing risk to mammals.

And even isolated mammalian infections provide the virus with new opportunities to thrive. A veterinarian at the Netherlands Wildlife Health Center, Dr. “There’s a risk of adaptation to mammals and then transmission between mammals, and then you have a new problem,” said Jolianne Rijks.

Some state officials said they are beginning to more routinely test sick mammals for the virus, particularly those with neurological symptoms. Dr. Webby said that samples of the virus should be sequenced in animals that test positive so that scientists can monitor for any potentially alarming changes.

Experts also encourage the public to report wild animals behaving strangely. “This is how it all started,” said Dr. Elsmo adds that “citizens see kits behaving abnormally and report them.”