Great black-backed gulls, which moved from Europe to eastern Canada last winter, may have been the first carriers of the deadly strain of bird flu to North America, which killed tens of millions of poultry and destroyed wild bird populations. there is.
Large-scale outbreaks have given researchers new opportunities to fine-tune their understanding of disease by studying which wild bird species, behaviors, and ecosystems play important roles in transmission. ..
Associate Professor of Biology at the University of Massachusetts Boston New paper It has become a hot topic.
However, “wild birds are incredibly rich in species,” she said, adding that “each has its own 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 the pathogen.
After the landing of migrating seagulls, a highly pathogenic avian influenza, also known as the H5N1 virus, exploded throughout North America. More than 77 million poultry raised in crowded conditions that contribute to the spread and evolution of the virus have been disposed of in dozens of countries.
For some experts, the H5N1 strain has caused more than 100 species of wild bird casualties so far, but the depth and breadth has been amazing and unprecedented. Among wild birds, it is very difficult to contain the spread and can pose a greater threat of spillover to other wildlife. Also, some wild birds, such as vines and seabirds, have a particularly low reproductive rate and are particularly vulnerable to endangered species.
The World Organization for Animal Health estimates that more than 383,000 wild bird deaths have been caused by the virus since October 2021, but the number is very high due to the extremely difficult tracking of sick and dead birds. It may be underestimated.
Pathogens spread rapidly to different regions and species at a much higher rate than at the last outbreak of 2014-2015.
“It affects a wider host range and doesn’t get stuck in wild birds like it used to,” said Dr. Hill. “It’s maintained in wild birds and it’s a terrifying outlook. For many of us in this field, my god, what do we do when it spreads to wildlife that we can’t control? ? “
It has long been thought that the main host of bird flu is the tapping of ducks such as mallards, teals and northern shovelers. It is essential for the spread of the infection, as it has mild or no symptoms and is widespread. However, new studies have shown that other birds, such as geese, play an underestimated role for their natural history.
“Goose is a little more tolerant of human disturbed areas,” said Dr. Hill. “Imagine the operation of a commercial poultry or backyard where they sprinkle grain.” It “attracts other cleaning birds like geese, seagulls, crows and magpies, so there is an interface between them. There is, “she said.
For example, the unique natural history of the great black-backed gull affects transmission. “Seagulls were a very rare host of highly pathogenic viruses,” said Dr. Hill. “When they carried it, on those rare occasions, they spread it really quickly. There is no such thing as a seagull for a very quick spread of the virus and a very long distance. Catch the tailwind and cross the Atlantic in 24 hours. “
This study may help other researchers track the pathogens followed by other viruses that are harmful to wildlife, as well as the continued spread of pathogens this year.
“Knowing that seagulls, geese, and ducks may carry this virus in different ways understands how to predict the spread of such viruses and ultimately more accurately models them. “It will greatly contribute to doing so,” said Jonathan Runstadler, professor and dean of the department. Co-author of Infectious Diseases and Global Health and Papers at Tufts University’s Cummings Veterinary School.
This data is used to predict whether a virus is present, when the bird may invade North America, and the number of birds that may be monitored to detect it. You can, “says Dr. Runstadler.
This year’s highly pathogenic strain of avian influenza occurred around 1996 and was first discovered in Chinese geese. Since then, it has circulated around the world in wild birds and poultry and has evolved as it moves from host to host.
After 10 years of evolution in 2005, the strain caused outbreaks in wild birds in wetlands of China.
The strain first appeared in the United States in 2014, moving birds from the Eurasian Continent across the Pacific to Alaska and further east, outbreaks in US poultry farms, killing 40 million turkeys and chickens. ..
However, after it reached the Midwest, mass slaughter stopped it and eliminated the spread of the virus in both wild and domestic populations.
“We don’t have a vaccine,” said Dr. Hill. “All that is included in the toolkit is to replace all the poultry. This is terrible, but to some extent successful.”
But this time it didn’t work to kill the infected poultry. This is because the virus has found homes in so many wild birds, causing the largest outbreak of bird flu to date.
In some places, authorities have warned chicken growers, and even those who keep backyard herds have warned them to keep their birds indoors, but in others, the threat seems to be gone.
“This virus is very good because it moves back and forth between the wild and the domestic,” said Dr. Hill. “There is no better way to amplify the virus than using a wild reservoir to tame relatives. That’s exactly what we did with chicken and ducks. The highly pathogenic virus is the virus. Occurs only when invading agricultural animals. “
In the Magdalen Islands, Quebec, wildlife authorities have recently found thousands of dead white gannets wiped out by the flu.
There is no way to predict whether the outbreak of influenza will decrease or worsen.
Some species, such as birds of prey, seabirds, and stag beetles, are also at very high risk of catching the virus because of their behavior. Dozens of bald eagles are known to have died from the flu. This is primarily due to predation on ducks and other birds that carry pathogens.
Birds that gather in large numbers are also at risk. “There are a lot of birds that flock, such as staghorn birds, terns, and seabirds. These birds can form large, large groups and become field activities for the virus,” said Dr. Hill. ..
Due to lack of oversight, it is difficult to assess the extent of devastation to different species. Better tracking along the migration route will help experts find ways to mitigate the spread of the virus.
Deaths of numerous shearwaters and other seabird species have been reported along the Atlantic coast of Massachusetts, Maine, New Hampshire, and Connecticut. Bird flu is suspicious, but has not been confirmed in tests.
“The geographic range of detection, the number of species obtained by detection, the amount of disease found in wild birds, all unprecedented,” said Andy Ramey, a wildlife geneticist at the US Geological Survey of Alaska. I am. A person studying bird flu. “It’s an unknown territory and it’s hard to know what to expect.”
There is also concern that parents may pass the disease to offspring of nests with an underdeveloped immune system during the breeding season of many species this year. Young wild birds are often exposed to low-pathogenic viruses, which are common and act mostly as inoculations, helping to strengthen the immune system.
One of the endangered species being monitored is the roseate tern in Buzzards Bay, off Massachusetts. The test has just begun and no sick bird has been found yet.
Carolyn Mostello, a coastal bird biologist at the Massachusetts Fisheries and Wildlife Service, said: “Nesting is slow. I hope there is no combination of poor food resources and bird flu. It can really act together to hurt the population.”
According to experts, bird flu has a very low risk to humans and has so far been detected in only two humans. However, as it persists and evolves, it can pose a serious threat to humans.
Dr. Hill said the main handicap for a better understanding of the outbreak was a lack of funding for efforts to track the spread. “Surveillance is really, really, really bad,” she said. “We spend very little money and time trying to anticipate this.”
