Happy Nice Mall

A great black-backed gull that migrated to eastern Canada from Europe last winter may have been the first carrier to North America of the deadly strain of bird flu that has killed tens of millions of domestic poultry and devastated wild bird populations.

Large-scale outbreaks have provided researchers with a new opportunity to fine-tune their understanding of the disease by examining which wild bird species, their behavior and ecology play a key role in transmission.

D., an assistant professor of biology at the University of Massachusetts Boston and lead author of a study. “Previous studies of bird flu have divided wild and domesticated birds into these broad categories,” said Nichola Hill. new paper About the subject.

But “wildbirds are incredibly species-rich,” he added, adding that “each one has a unique natural history and behavior.”

For example, knowing which migratory species carry the pathogen can help predict when and where the pathogen will arrive based on migration routes.

After the migrating gull came ashore, the highly pathogenic avian flu, also known as the H5N1 virus, broke out in North America. More than 77 million poultry were culled in dozens of countries, many of which were raised in crowded conditions that fueled the spread and evolution of the virus.

According to some experts, the damage this H5N1 strain is doing to wild birds – it has hit more than 100 species so far – is alarming and unprecedented in its depth and breadth. Controlling spread among wild birds can be very difficult, posing a greater spread threat to other wildlife. And some wild bird species, such as cranes and some seabirds, are particularly vulnerable, especially those with low reproductive rates and those that are already endangered.

The World Organization for Animal Health estimates that more than 383,000 wild bird deaths since October 2021 can be attributed to the virus, but the number can be underestimated due to how difficult it is to keep track of sick and dead birds.

The pathogen spread rapidly across various regions and species, at rates much higher than the last outbreak in 2014-2015.

Dr. “It’s affecting a larger host range and isn’t bogging down wild birds like it used to,” Hill said. “It continues in wild birds, and it’s a frightening prospect. For many of us in this field, my God, what do we do when we mess with an uncontrollable wild animal?”

It has long been assumed that the main hosts of avian flu are daring ducks, such as mallard, teal, and rower, which feed on the surface and just below with their rumps in the air. Because their symptoms are mild or nonexistent, they are critical to spreading and carry it everywhere. But the new study found that other birds, such as geese, play an underestimated role because of their natural history.

Dr. “Geese are a little more tolerant of human-disturbed areas,” Hill said. “Imagine a commercial poultry business or backyard business where they spread the grain around.” This “attracts geese and other scavenger birds such as gulls, crows and magpies, so there is an interface between them,” he said.

For example, the unique natural history of the black-backed gull, the world’s largest gull, plays a role in the contamination. Dr. “Seagulls were really rare hosts for highly pathogenic forms of the virus,” Hill said. “When they carried it, in those rare cases, they spread really fast. The virus spreads really fast and for really long distances, there’s nothing like a seagull. They’re going to catch a tailwind and cross the Atlantic in 24 hours.”

The study could help other researchers track not only the continued spread of this year’s pathogen, but also the pathways of other viruses harmful to wildlife.

“Knowing that seagulls, geese and ducks can move this virus in different ways is a huge contribution to understanding or ultimately modeling more accurately how such a virus is expected to spread,” said Professor and Department Chair Jonathan Runstadler. Infectious Diseases and Global Health at Tufts University Cummings School of Veterinary Medicine and co-author of the paper.

Dr. “The data allow us to predict whether there is an emerging virus, when this bird might enter North America, and what bird populations we can target to detect it,” Runstadler said.

The highly pathogenic strain of this year’s avian flu emerged in 1996 and was first found in a domestic goose in China. It has since traveled around the world in wild and domestic birds, evolving as it travels from host to host.

In 2005, after a decade of evolution, the species caused a major outbreak of wild birds in wetlands in China.

The species first appeared in the United States in 2014, traveling in birds migrating from Eurasia across the Pacific to Alaska and further east, and has caused epidemics in US poultry farms that have killed 40 million turkeys and chickens.

But once it reached the Midwest, mass cullings stopped it and eliminated viral spread for both wild and native populations.

Dr. “We don’t have a vaccine,” Hill said. “The only thing in our toolbox is to replace all of our poultry, which is horrible, but it has been successful to some extent.”

But killing infected poultry didn’t work this time, partly because the virus was able to find a home in a large number of wild birds, which has spawned the largest bird flu outbreak ever.

In some places the authorities have warned chicken producers and even backyard flock people to keep their birds indoors, while in others the threat seems to have passed.

Dr. “This virus is so good because it plays ping pong between wild and tame,” Hill said. “There is no better way to reproduce a virus than to take a wild reservoir and tame a close relative. That’s exactly what we did with chickens and ducks. Highly pathogenic forms of the virus only appear when the virus infects farm animals.”

In Quebec’s Magdalen Islands, wildlife officials have discovered the carcasses of thousands of white boobies recently wiped out by the flu.

There is no way to predict whether flu epidemics will decrease or get worse.

Some species, such as raptors, seabirds, and shorebirds, are also at greater risk of contracting the virus because of their behavior. Dozens of bald eagles are known to have died from the flu, largely because they preyed on ducks and other birds that carried the pathogen.

Birds collected in large numbers are also at risk. Dr. “There are a lot of flocked birds – shorebirds, sea terns and seabirds – that form large, large groups that could just be a field day for the virus,” Hill said.

It is difficult to assess the extent of destruction by various species because surveillance is lacking. Better monitoring along migration routes will help experts find ways to reduce the spread of the virus.

Multiple deaths of shearwater and other seabird species have been reported off the Atlantic coasts in Massachusetts, Maine, New Hampshire, and Connecticut. Bird flu is suspect, although tests don’t confirm this.

“The geographic extent of the detection, the number of species we’re getting with the detections, the amount of disease we’re seeing in wild birds, they’re all unprecedented,” said Andy Ramey, a US Geological Survey research wildlife geneticist in Alaska. who studies bird flu. “It’s an unknown territory and it’s hard to know what to expect.”

There is also concern that during this year’s breeding season in many species, parents may pass the disease on to offspring in the nest with underdeveloped immune systems. Young wild birds are often exposed to common, low-pathogenic viruses that almost act as vaccines, helping to boost their immune systems.

One of the endangered species is the rose tern in Buzzards Bay off the Massachusetts coast. Testing is just beginning and no sick bird has yet been found.

“It looks like it’s going to be a tough food year for terns,” said Carolyn Mostello, a shorebird biologist with the Massachusetts Department of Fisheries and Wildlife. “Deployment has been slow. I hope we don’t experience a combination of poor food supplies and bird flu; this could act together to really harm the population.”

Experts say that bird flu poses a very low risk to humans and has only been detected in two people so far. However, as it continues and evolves, it can acquire the ability to pose a serious threat of spread to humans.

Dr. Hill said the biggest obstacle to better understanding the outbreak has been the lack of funding for efforts to monitor the spread. “My surveillance is really, really, really bad,” he said. “We spend very little money and time trying to get ahead of this.”