Avian flu isn’t yet a direct threat to humans, experts say, but they’re keeping a close eye on the virus – Orange County Register

Avian flu has infected a record number of birds and some mammals in the United States, and scientists are watching closely.

World Health Organization director-general Tedros Adhanom Ghebreyesus said Thursday the risk to humans was low, but added: “We cannot assume that this will remain the case.”

As with the coronavirus that causes Covid-19, which is thought to have started in animals before spreading to humans, some animal viruses are capable of mutating, skipping species, sickening humans and spreading rapidly around the world.

But the highly pathogenic bird flu is not Covid-19. Scientists are reassuring the public that, with few exceptions, the virus has not spread to humans in sufficient numbers to trigger an outbreak.

However, it has gone well beyond birds, and its recent spread among members of a different species has some experts concerned about the way the virus is changing.

What is bird flu?

Avian influenza is a type A influenza virus that originates in birds. The version that causes problems mainly in America and Europe is called the H5N1. There are several subtypes, and the currently widely circulating H5N1 avian influenza viruses are genetically distinct from previous versions of the virus, according to the US Centers for Disease Control and Prevention.

As of late 2022, scientists have detected this virus in more than 100 species of wild birds such as ducks, gulls, geese, hawks and owls in the United States.

Globally, this strain of the virus has actually been around much longer, said Richard Webby, an infectious disease researcher at St. Jude Children’s Research Hospital in Memphis, Tennessee, and director of the WHO Collaborating Center for Studies in the Ecology of Influenza in Animals and Birds.

“We saw a kind of great-great-grandfather of the virus in Southeast Asia in the late 1990s and have followed its evolution and change ever since,” Webby said.

By the 2000s it had spread to parts of Europe and Africa, and then was carried to the rest of the world by infected migratory birds. It recently came to America, Webby said.

The first infection with this version of the virus was reported in wild birds in the United States in January 2022, according to the CDC. The next month, the US Department of Agriculture announced an outbreak among turkeys at a commercial facility.

Studies have shown that avian flu can spread to songbirds, but those that usually congregate at feeding sites — like cardinals, sparrows or blue jays — and those you can see on the street, like doves or crows, don’t usually carry avian flu viruses that do so would be a threat to humans, according to the CDC.

Ducks and geese can transmit the virus without appearing ill. Poultry isn’t always so lucky.

Highly pathogenic avian influenza causes “very high mortality rates” in chickens and turkeys. The disease can affect multiple internal organs and kills 90% to 100% of chickens within 48 hours of infection, according to the CDC.

Because it can spread quickly, farmers usually have to kill uninfected birds along with infected birds to prevent a larger outbreak. It is considered one of the greatest known threats to domestic birds.

As of Wednesday, 6,111 cases had been identified in wild birds across all 50 states, according to the USDA. The virus has affected more than 58.3 million poultry birds in 47 states, according to the CDC.

The sheer volume of cases means the virus has a better chance of spreading to other species, experts say.

More and more animals are getting sick

Bird flu spreads through things like feces and saliva. It can also spread through contact with a contaminated surface.

The virus has infected many mammals in the United States, primarily in the West and Midwest, as part of the recent outbreak.

Cases have been reported in bears and foxes in Alaska, according to the USDA. The virus has also been found in a bobcat in California, a skunk in Colorado, a raccoon in Washington, possums in Illinois and Iowa, a mountain lion and grizzly bear in Nebraska, seals in Maine, and even a bottlenose dolphin in Florida.

A total of 17 non-bird species were infected in 20 states.

Scientists say all of these sick mammals likely picked up the virus by eating or otherwise interacting with infected birds.

But in a worrying development last autumn, the virus appeared to be spreading – perhaps for the first time – between mammals at a mink farm in Spain, according to a study published in the journal Eurosurveillance.

The mink developed bloody noses, developed tremors, lost their appetite and appeared depressed, the scientists said, and had to be killed to keep the threat at bay.

The virus didn’t spread to people working on the mink farm, but what worried scientists was the numerous mutations found in the virus that differentiated it from sequences found in birds. A mutation made it better at replicating in mammals, although it’s not clear if the mutation was in the virus before it got to the farm.

“But when it starts to spread from one mammal to the next mammal to the next mammal, it’s in the environments where we think it’s most likely to pick up those changes that allow us to switch hosts.” , and that’s why we’re worried,” Webby said.

A handful of human cases

As of December 2021, fewer than 10 human cases of bird flu have been known and none have been transmitted from person to person, the CDC says.

The latest US case involved a person in Colorado who became ill after killing infected birds in April. The person reported feeling tired for a few days. They were isolated and treated with an antiviral drug, the CDC said.

The agency said at the time that the public health threat was low but urged people exposed to birds to take precautions.

“People who typically get sick are among those individuals who have very intense interactions with wild animals, whether living or dead,” said Dr. Columbia University Mailman School of Public Health. “I wouldn’t say we’re in for another pandemic because we’re not. Were not there.

“What we need to do now is watch very closely how this is spreading. We need to contain it as best we can in farms and wildlife,” he added.

This is how you stay safe

Although the threat to humans is low, the CDC suggests avoiding direct contact with wild birds.

Webby says if you have to deal with a dead bird, e.g. B. if you need to remove him from a feeding station, use gloves and a mask. Always wash your hands after touching birds or bird feeders.

It’s safe to eat poultry and eggs that are properly handled and cooked, the CDC said. Avian flu is not a foodborne disease and the poultry industry is closely monitored and has strict health standards that include bird flu surveillance and control.

Always cook poultry and eggs at 165 degrees, a temperature that kills bacteria and viruses, including bird flu.

In the highly unlikely event that someone does become ill, the CDC recommends seeking treatment immediately. Most bird flu infections can be treated with currently available antiviral flu drugs, the agency says.

The U.S. government also has a stockpile of vaccines, including against bird flu viruses, that could be used if this flu ever spreads easily from person to person, the CDC says.

“The odds aren’t zero that you could get that, and anything you can do to further reduce that risk is a good thing,” Webby said. “But you probably have to work really hard to catch this virus.”