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Deadly new bird flu infects wild birds and may not go away: NPR

Waterfowl and the raptors that feed there, like this bald eagle and snow goose, have both been killed by the new bird flu virus.

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Jeff Goulden/Getty Images

Deadly new bird flu infects wild birds and may not go away: NPR

Waterfowl and the raptors that feed there, like this bald eagle and snow goose, have both been killed by the new bird flu virus.

Jeff Goulden/Getty Images

A newly arrived bird flu is sweeping wild bird populations across the United States, and that may spell trouble for poultry farmers who have been doing their best to control this flu outbreak in their flocks.

Some 24 million poultry such as chickens and turkeys have already been lost, either because they died from the virus or because they were killed to prevent its spread. But unlike a similar outbreak of bird flu seven years ago, this one is unlikely to end.

This is because this particular flu virus seems able to hang around in wild bird populations, which can transmit the virus to poultry farms. While chickens and turkeys infected with the virus quickly become ill and die, some waterfowl can stay healthy with the virus and carry it over long distances.

Scientists believe that wild migratory birds brought this virus to North America a few months ago. Since then, more than 40 species of wild birds in more than 30 states have tested positive. This strain of bird flu virus has appeared in everything from crows to pelicans to bald eagles.

“It’s somewhat surprising how widespread it is already in North America,” says Jonathan Runstadler, a flu researcher at Tufts University. “It is clearly able to persist and be transmitted from year to year in parts of Asia, Europe, Africa, and I don’t think we should be surprised if that’s going to be the case. here.”

As the virus moves across the country and potentially takes hold in the long term, new animal species will likely become infected. This could give this new pathogen a chance to genetically mingle with flu viruses already circulating in the United States.

“What that means for the virus in terms of evolution, change, we just don’t really know,” says Richard Webby, flu researcher at St. Jude Children’s Research Hospital.

There has only been one known human case

So far, the risk to humans appears low.

But because related bird flu viruses have spread many times in the past, public health experts are watching for any signs of genetic modification that could make the virus capable of spreading in humans.

“We are concerned about any bird flu virus circulating in domestic poultry or wild birds,” says Todd Davis, animal-to-human disease expert at the Centers for Disease Control and Prevention (CDC). “Because humans generally have no prior immunity to these viruses, if they were to become infected and spread the virus to other humans, then we could have another pandemic virus on our hands.”

This virus lacks genetic characteristics previously associated with related avian influenzas that have infected humans. And the only person known to have contracted this particular bird flu virus was an elderly person in the UK who lived near ducks; while some of the ducks fell ill and died, their owner never had symptoms.

The CDC is monitoring the health of more than 500 people in 25 states who have been exposed to infected birds, Davis says. Although a few dozen people developed flu-like symptoms, all were tested and none tested positive for this virus.

Raptors could be particularly affected

Wildlife experts have long known that highly pathogenic bird flus like this are circulating in Europe and Asia. And they worried about the possible threat these viruses could pose to American birds.

Then, in December 2021, chickens and other poultry fell ill and began to die at a farm on the island of Newfoundland, Canada. Tests have shown that this deadly bird flu virus has crossed the Atlantic.

“The very first moment it arrived in North America, it was a wake-up call for us,” says Bryan Richards, emerging disease coordinator at the US Geological Survey’s National Wildlife Health Center.

In January, government officials announced his arrival in the United States after a whistling duck in South Carolina tested positive. The last time a dangerous bird flu entered the country, Richards says, “the number of cases where we detected this particular virus in wild birds was very, very limited.”

In contrast, this latest bird flu virus is detected everywhere in sick and dying birds.

“This outbreak in the wild bird population is much larger than what we saw in 2014 and 2015,” says David Stallknecht, avian flu researcher at the University of Georgia. “Just a lot more birds seem to be affected.”

Waterfowl and raptors that eat their carcasses pay the price.

In Florida, for example, more than 1,000 pochards have succumbed to the virus. In New Hampshire, about 50 Canadian geese died in a single event. In the Great Plains states, wildlife experts have seen mass mortalities among snow geese.

“Additionally, there are a host of other species, including black vultures and bald eagles and some of the other scavenger species, that likely became infected by consuming the carcasses of these waterfowl,” says Richards.

It remains to be seen what impact this virus will have on American bird species.

In Israel, when this virus hit an area where about 40,000 common cranes had congregated for the winter, “they lost 8,000 of those birds in a matter of weeks,” says Richards. “So when you start thinking about losing 20% ​​of a specific population of wild birds, that’s a pretty big impact.”

Poultry farmers slaughter their flocks

Chickens and turkeys raised by the poultry industry have suffered the most, and farmers are preparing for even more.

The bird flu that struck in 2014 and 2015 killed more than 50 million birds and cost the industry billions of dollars. At the time, the highest number of cases occurred in the month of April.

“So I think I’m kind of holding my breath this month,” says Denise Heard, director of research programs for the US Poultry & Egg Association.

The virus has a number of ways to jump from wild birds to poultry, Heard says. Since the last outbreak, the industry has worked to educate producers on how to protect their herds.

“Wild migratory waterfowl are always flying overhead and when they poop, that poop falls to the ground,” she says, explaining that the virus can then end up in nesting boxes on boots or be inadvertently moved from a farm. to another on vehicles.

Heard says there currently appears to be less farm-to-farm spread of the virus than during the last major outbreak. Instead, there are more isolated cases popping up, possibly because wild birds bring the viruses to farms and backyard flocks.

If this virus persists in wild bird populations – which some scientists think is likely – poultry farmers may simply have to learn to live with this problem.

“I hope that’s not the case. I hope that in the United States this infection will die soon and that the virus will disappear again like it did in 2014”, says Ron Fouchier, virologist at Erasmus Medical Center in the Netherlands. . “But there is no guarantee for that, as we have seen in Europe now that this virus has remained present for several consecutive years.”

Since December, European farmers have had to cull more than 17 million birds. “So it’s very similar to the situation in the United States,” says Fouchier. “And we are seeing mass mortalities in wild birds.”

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