The worst bird flu outbreak on record threatens to stretch into a second year as the United States scrambles to contain a virus that has already sent prices of some foods soaring amid an egg shortage.

Nearly 58 million birds from commercial and backyard flocks have been culled in the US since last February, according to the US Department of Agriculture. Animal and Plant Health Inspection Service.

Experts say the virus, known as Highly Pathogenic Avian Influenza, or HPAI, has been difficult to contain because it appears to be more prevalent in wild birds now than in previous outbreaks, a development that also makes future infections more likely. And while the risk of the virus spreading to humans remains low, scientists say communities will feel the consequences of such a severe and protracted outbreak for months to come.

“As it stands now, this is the largest animal emergency USDA has ever faced in this country,” said Gino Lorenzoni, an assistant professor of poultry sciences and avian health at Pennsylvania State University.

More than 40 million laying hens have been culled in the US alone, causing the price of eggs across the country to skyrocket, Lorenzoni said. Months before, the outbreak of «bird flu» drove the cost of turkey meat to record levels.

The virus can put commercial poultry farms out of business for extended periods.

“They have to remove dead birds, disinfect their facilities and bring in new birds; that’s a multi-month process to do it,» said Kevin Snekvik, executive director of the Washington Animal Disease Diagnostic Laboratory at Washington State University. «That’s when egg production hits.»

Eggs are seen on a shelf at Pioneer Supermarkets in Brooklyn
Eggs on a shelf at Pioneer Supermarkets in Brooklyn, NY, on Thursday.File Michael M. Santiago/Getty Images

Efforts are underway to prevent infections in commercial and backyard flocks, but curbing the outbreak has been challenging because the virus appears to have gained a foothold in wild bird species, said Biao He, a professor of infectious diseases in the University’s Faculty of Sciences. from Georgia. Veterinary Medicine.

As these birds migrate, across continents and oceans, they can carry the virus with them.

“This is how the virus can go from Asia to Europe to North America, all over the world,” he said.

Poultry can become infected through direct exposure to wild birds, but it is most likely from fecal matter contaminating the soil around farms or yards.

Once that happens, it is usually necessary to cull entire flocks.

“The virus spreads very, very quickly within the flock, so even if the birds don’t appear sick, they will eventually die very soon,” Lorenzoni said. “The best way to stop the spread of the disease is if we remove all birds that are in close contact with the contaminated birds.”

Rescued chickens gather in an aviary at Farm Sanctuary's Southern California Sanctuary
Rescued chickens gather last year in an aviary at Farm Sanctuary’s Southern California Sanctuary in Acton, California.File Mario Tama / Getty Images

Bird flu monitoring and prevention have improved since the last major outbreak in 2015, Lorenzoni said, when an estimated 50 million birds were killed in six months. He USDA Defend the Flock Program includes, for example, information on biosecurity measures and how to detect signs of disease.

Still, the scale of the spread is putting pressure on animal health labs. Suresh Kuchipudi, acting director of the Animal Diagnostic Laboratory at Pennsylvania State University, said three animal testing labs in Pennsylvania process several thousand samples each week. His lab largely operates seven days a week.

«The spread is much more complex than we normally predict,» Kuchipudi said. «Nothing like this has happened in the past and the question is: what has changed?»

The prevalence of the virus in nature presents new challenges for its containment. Many migratory birds don’t get sick with bird flu, which means how widespread it is in nature isn’t well understood, Lorenzoni added.

Local weather conditions also influence how the virus spreads. The sun can, for example, disinfect surfaces naturally, while darker days help viral particles survive on surfaces contaminated by infected bird droppings, Lorenzoni said.

And if the outbreak persists until spring, infections could become even more difficult to prevent as a new wave of bird migrations begins.

There is also concern that the virus could mutate as it continues to spread or infect other animals. Although experts have said that the virus rarely infects humans, HPAI has been detected in mammals such as skunks, raccoons, harbor seals, red foxes and bears. according to the USDA.

If allowed to spread unrestrained, the pathogen could evolve in a way that makes it more devastating or harder to control.

“A virus has only one mind: it has to replicate, reproduce,” he said. “With all those replications, you can accumulate a lot of different changes. This is happening as we speak, and that’s why I’m afraid the flu will be with us for a long time.»