Avian flu spread in the US worries poultry industry

The virus does not spread efficiently among humans, but it is extremely deadly, with a fatality rate of 60 per cent. PHOTO: REUTERS

NEW YORK (NYTIMES) - A highly contagious and deadly form of avian influenza has been barrelling across the eastern half of the United States in recent weeks, killing wild birds and farmed poultry and raising fears that an unchecked outbreak could prove calamitous for an industry that was devastated by a similar virus seven years ago.

Since early January, when it began killing chickens in north-east Canada, the virus has been identified in migratory waterfowl from Florida to Maine, and has infected backyard chickens in Virginia and New York and sickened thousands of turkeys in Kentucky and Indiana, prompting mass cullings and import bans.

On Wednesday (Feb 23), federal officials announced that the virus, a so-called highly pathogenic avian influenza, had been found in a Delaware commercial chicken farm on the Delmarva Peninsula, home to one of the country's largest concentrations of poultry farms.

Experts suspect wild birds returning from winter feeding grounds are spreading the virus, most likely through contaminated droppings. With the peak springtime migration still weeks away, many fear the worst is yet to come.

"It's very concerning given how quickly this thing is accelerating," said Dr Henry Niman, a biochemist in Pittsburgh who studies the genetic evolution of viruses and has been tracking the outbreak's spread across the country. "I think we could see historic levels of infections."

The 2014-15 outbreak is considered the most destructive in the nation's history. It sent poultry and egg prices soaring and cost the industry more than US$3 billion (S$4.07 billion) - although the federal government compensated farmers for lost flocks.

In the end, nearly 50 million birds were killed by the virus or destroyed to prevent its spread, a vast majority of them in Iowa and Minnesota.

Federal officials have been urging poultry growers to report sick or dying birds and to tighten their farms' biosecurity measures, which includes preventing contact between wild birds and domestic animals.

"It's important to note that avian influenza is not considered to be a risk to public health and it's not a food safety risk," Mr Mike Stepien, a spokesperson for the Department of Agriculture's Animal and Plant Health Inspection Service, said in an email.

Although the danger to humans is low, scientists are keeping a close eye on the virus, the Eurasian H5N1, which is closely related to an Asian strain that has infected hundreds of people since 2003, mostly those who had worked with infected poultry.

That virus does not spread efficiently among humans, but it is extremely deadly, with a fatality rate of 60 per cent, according to the Centres for Disease Control and Prevention.

The strain spreading across the United States has not jumped to humans, but virus experts and public health researchers say the mounting infections among birds are worrisome because they increase the possibility that the virus could mutate in ways that make it more infectious to people.

The virus has also been coursing through Asia, the Middle East and Europe. In recent weeks, 300 outbreaks have been reported in 29 European countries. In Israel, an outbreak at a nature reserve killed thousands of cranes.

A photo from Nov 18, 2015, shows a brooding barn which had to destroy 56,000 birds because of the avian flu in Iowa. PHOTO: NYTIMES

At the moment, turkey farmers, especially those in Indiana and Kentucky, are most worried.

Over the past two weeks, several farms in those states have been shuttered after officials discovered the virus among birds that spend their entire lives crammed into massive sheds. Farmers say they have been stunned by how efficiently the virus kills, with animals dying hours after the initial infection.

In Indiana, state officials have moved quickly, euthanising more than 100,000 birds and throwing a 6-mile (9.6km) cordon around affected farms - a containment area within which exports are halted and birds are tested daily.

"Everyone is on super high alert and trying to be as prepared as possible because we all remember the devastation of 2014 and 2015," said Dr Denise Heard, a veterinarian with the US Poultry & Egg Association.

But hypervigilance has its limits, especially against a microscopic pathogen that can infiltrate a barn on the leg of a single housefly.

For a growing number of scientists, the real threat is the nation's industrialised system of meat and dairy production, with its reliance on genetically identical creatures packed by the thousands inside huge confinement sheds.

Nearly all the 9 billion chickens raised and slaughtered in the United States each year can trace their lineage to a handful of breeds that have been manipulated to favour fast growth and plump breasts. The birds are also exceptionally vulnerable to outbreaks of disease.

"They all have the same immune system, or lack of an immune system, so once a virus gets inside a barn, it's going to spread like wildfire," said Dr Hansen, the public health veterinarian.

Mr Andrew deCoriolis, executive director of Farm Forward, a sustainable agriculture advocacy group, said the lack of genetic diversity isn't just a threat to the nation's food supply; it is also a potential threat to public health.

More than half the 22 strains of novel influenza virus that the CDC has identified as "of special concern" to human health are avian influenza viruses, he said, noting that a 2018 study examining the emergence of 39 highly pathogenic avian viruses found that all but two of them had emerged on industrial poultry farms.

He said the sector's emphasis on biosecurity and infection containment obscures a larger, thornier issue that requires a fundamental rethinking of meat and egg production in the United States.

"Instead of asking how factory farms can prevent infections that originate in the environment, which is how they frame it now, we should be asking how they can prevent infections that originate on factory farms," he said. "If we keep raising more and more animals in these conditions, we should expect the exact outcome we're getting because that's how the system is set up."

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