U.S. egg industry sees record chicken deaths from bird flu outbreak

More than 20 million egg-laying chickens in the U.S. died last quarter because of bird flu, data from the U.S. Department of Agriculture shows, marking the worst toll inflicted on America's egg supply since the outbreak began.

The record number of chicken deaths, which includes those birds culled when infection is discovered in a flock, come as figures show egg prices have soared to the highest they have been in years, driven in large part by the virus.

"Unlike in past years, in 2024, all major production systems experienced significant losses including conventional caged, cage-free, and certified organic types," a USDA report said this month.

Taxpayers will pick up the tab for the lost birds. To incentivize farmers to quickly report and stomp out the virus, a USDA program pays producers for the eggs and poultry they cull.

Last year, the Animal and Plant Health Inspection Service said it had spent $1.25 billion on payments to farmers since the outbreak started in 2022.

Why are bird flu cases high right now in poultry?

U.S. officials brace every winter for upticks in bird flu because migrating wild birds that spread the virus fly south during the colder months.

It's also easier for the virus to spread in the winter. Heat and sunlight degrade the virus on surfaces, the USDA says.

This winter has been different because a strain of the bird flu virus has spilled over into dairy herds too, leading to hundreds of infected herds.

Authorities suspect the virus has been hitching a ride in droplets of contaminated raw milk. Those are ferried between farms by workers' clothing, equipment and animals shared between farms.

California has been hit especially hard in recent months, forcing the state to declare a state of emergency to try to respond to the bird flu outbreak.

This winter's surge of bird flu is from a different virus than the uptick of seasonal flu infections that also drives humans to emergency rooms every winter.

While bird flu led to millions of dead poultry over the past year, the Centers for Disease Control and Prevention has tallied only 66 confirmed human cases in the U.S. from bird flu viruses.

Most American cases of bird flu have been mild. A majority were farm workers who were infected after close contact with animals infected by a bird flu strain that spilled over into dairy cows in late 2023.

Researchers think this bird flu strain mutated to be milder to humans than other variants spreading in the wild. Those other strains usually cause more severe disease when they jump into humans.

Can animals be vaccinated for bird flu?

The USDA announced this week it is drawing up a new stockpile of poultry vaccines. That vaccine will target the D1.1 strain of the virus, which has been spreading in wild birds and was recently to blame for a fatal human case in Louisiana.

But officials said it's unlikely the vaccine will be used. The Biden administration has been weighing the possibility of vaccinating poultry for bird flu for years.

That is different from plans to potentially vaccinate cows for bird flu, which the USDA says appears "more feasible and more likely to be successful" in battling the virus. Seven potential vaccines are now being tested in field safety trials, the department said.

One major hurdle has been the fear that vaccines will only hide the symptoms of the otherwise highly lethal disease in birds. That could result in export restrictions from countries afraid the virus could spread to them through poultry products.

In 2023, the USDA banned imports of some products from Europe after authorities announced they would start vaccinating some poultry for bird flu.

Spread of the virus through contaminated meat in the U.S. has already happened during this year's outbreak at least twice: raw pet food made from sick animals was linked to an outbreak that killed cats in California and Oregon.

A Food and Drug Administration spokesperson told CBS News that the agency is now urging the animal food supply chain to take steps to curb the threat of the virus spreading, including heat treatment to kill off the virus and avoiding using infected animals.

"All recent detections of H5N1 in cats had these things in common: the infected cats ate wild birds, unpasteurized milk, raw poultry, and/or raw poultry pet food," the spokesperson said.