A large black-backed seagull migrating from Europe to eastern Canada last winter could be the first carrier of the deadly strain of bird flu in North America, which has killed ten million domestic birds and destroyed wild bird populations.
Large-scale occurrences have provided a new opportunity for researchers to consolidate their understanding of the disease by examining the role of wild bird species, behaviors, and ecology in their transmission.
“Previous research into bird flu has led to these large categorizations of wild and domestic birds,” said Drs. Nichola Hill, Assistant Professor of Biology at Boston University in Massachusetts and lead author of a new paper on the subject.
But “wild birds are very rich in species,” he said, and “each has its own unique natural history and behavior.”
Knowing which migratory species carry the pathogen, for example, can help predict when and where they may arrive via migratory routes.
After the migrating seagull landed, a highly pathogenic bird flu, also known as the H5N1 virus, broke out in North America. More than 77 million birds, most of them seeded in crowded conditions that spurred the spread and evolution of the virus, have died in dozens of countries.
According to some experts, the damage caused by this H5N1 strain to wild birds, which has so far affected more than 100 species, has been worrying and unprecedented in its depth and breadth. Among wild birds, spreading can be very difficult, creating a greater threat of extinction for other wildlife. And some wild bird species, such as cranes and some seabirds, are particularly vulnerable, especially those with low rates of reproduction and already at risk.
The World Organization for Animal Health estimates that more than 383,000 wild birds have been blamed for the virus since October 2021, although the number could be underestimated, making it difficult to track down sick and dead birds.
The pathogen has spread rapidly in several regions and species, with a much higher rate than in the last outbreak in 2014-2015.
“It’s affecting a larger host range and it’s not as extreme as it used to be in wild birds,” said Drs. said Hill. “It’s kept in wild birds, and that’s scary. For many of us in this field, my God, what do we do when we are thrown into a wild animal out of control?
It has long been believed that the main hosts of bird flu are duck ducks, such as duck ducks, teal and shovel, which feed on the surface and bottom with their indentation in the air. They are essential for spreading because they have mild or no symptoms and can be carried away. New research, however, has shown that other birds, such as geese, have been underestimated because of their natural history.
“Geese are a little more tolerant of human-disturbed areas,” said Drs. said Hill. “Imagine a commercial bird operation or a backyard operation where they spread the grain.” That’s “like geese and other birds of prey, like seagulls and crows and needles, so there’s an interface to attract them,” he said.
The special natural history of the black-backed gull, the largest gull in the world, for example, has a role to play in transmission. “Seagulls were very rare hosts for highly pathogenic forms of the virus,” said Drs. said Hill. “It simply came to our notice then. There is no such thing as a seagull spreading the virus really quickly and over very long distances. They will catch the wind in their tails and cross the Atlantic in 24 hours. ”
The study could help other researchers not only follow the ongoing spread of this year’s pathogen, but also follow the paths taken by other viruses that are harmful to wildlife.
“Knowing that anchovies, geese, and ducks are moving this virus in different ways is a great contribution to understanding how this virus is expected to spread, or ultimately more accurately,” said Jonathan Runstadler, professor and head of the Department of Infections. Disease and Global Health Tufts University Cummings Veterinary School and co-author of the paper.
The data “allows us to detect whether a virus is being created, when that bird can enter North America, and what bird populations we can target.” said Runstadler.
This year’s highly pathogenic bird flu lineage originated around 1996, when it was first found in a Chinese domestic goose. Since then, it has roamed the wild and domestic birds around the world, evolving as it travels from one host to another.
In 2005, after a decade of evolution, tensions were high in wild birds in China’s wetlands.
The tension first appeared in the United States in 2014 traveling from Eurasia to the Pacific Ocean in Alaska and in the Far East migrating birds, causing outbreaks in U.S. poultry farms and killing 40 million turkeys and chickens.
After reaching the Midwest, however, mass killings halted it, eliminating the viral spread of both wild and domestic populations.
“We don’t have vaccines,” Dr. said Hill. “All we have in our toolbox is to change all of our birds. It’s huge, but to some extent it was successful.”
But killing the infected birds has not been worth it this time, partly because the virus has been able to find a home in so many wild birds, creating the biggest outbreak of bird flu ever.
In some places, officials have also warned chicken producers and people keeping herds in the yard to keep the birds indoors, while in other places the threat seems to have been overcome.
“This virus is very good because it spreads between wild and domestic ping pong,” said Dr. said Hill. “There’s no better way to amplify a virus than to take a wild reservoir and house a close relative. That’s exactly what we’ve done with chickens and ducks. Very pathogenic forms of the virus only occur when the virus enters farm animals.”
In the Magdalena Islands of Quebec, wildlife officials recently discovered the bodies of thousands of white gannets that had been wiped out by the flu.
There is no way to predict whether the flu will decrease or worsen.
Some species, such as predators, seabirds and seabirds, are at high risk of catching the virus due to their behavior. Dozens of bald eagles have been reported to have died from the flu, mainly from catching pathogenic ducks and other birds.
Birds that gather in large numbers are also endangered. “There are a large number of birds – shorebirds, shorebirds and seabirds – that make up massive and massive groups and this could be a day in the field of the virus,” said Drs. Hill.
It is difficult to assess the extent of the catastrophe of several species due to lack of surveillance. Better monitoring of migration routes would help experts find ways to reduce the spread of the virus.
The Atlantic coast of Masachussetts, Maine, New Hampshire and Connecticut have reported the deaths of many species of partridges and other seabirds. Bird flu is suspected, although tests have not confirmed it.
“The geographic range of detection, the number of species we’re getting with the detections, the number of diseases we’re seeing in wild birds, all of this is unprecedented,” said Andy Ramey, a geneticist for wildlife in Alaska at the U.S. Geological Survey. which examines bird flu. “It’s an unknown territory and it’s hard to know what to expect.”
He is also concerned that during the breeding season of many species this year, parents may pass the disease on to nestlings because they have poorly developed immune systems. Young wild birds are often exposed to low-pathogenic viruses, which are common and can serve almost as an inoculation, helping to strengthen the immune system.
One endangered species is the pink bell in Buzzards Bay off the coast of Massachusetts. Tests are underway and no sick bird has yet been found.
“The feeding year seems like a tough year for the woodpeckers,” said Carolyn Mostello, a coastal bird biologist with the Massachusetts Fisheries and Wildlife Division. “Nesting has been slow. Fortunately, we do not have a scarce food resource and a combination of bird flu; that could work together to really hurt the population. ”
Experts say that bird flu poses a very low risk to humans and has so far been detected in only two humans. However, as it persists and evolves, it can have the potential to pose a serious threat to humans.
Dr. Hill said a major inability to better understand the outbreak was a lack of funding for efforts to continue the expansion. “The care is really, really, really bad,” he said. “We are spending very little money and time to advance this.”