What to Know About the Bird Flu Outbreak (2024)

From Wyoming to Maine, an outbreak of the highly contagious bird flu has swept across farms and backyard flocks in the United States this year, prompting millions of chickens and turkeys to be culled.

Iowa has been particularly hard hit, with disasters being declared in some counties and the state canceling live bird exhibits in an order that may affect its famed state fair.

Here is what we know about the bird flu.

What is avian influenza?

Better known as the bird flu, avian influenza is a highly contagious and deadly virus that can prey on chickens, turkeys and wild birds, including ducks, geese and eagles. It spreads via nasal secretions, saliva and fecal droppings, which experts say makes it difficult to contain.

Symptoms of the virus include a sudden increase in the mortality of a flock, a drop in egg production and diminished consumption of feed and water.

The virus, Eurasian H5N1, is closely related to an Asian strain that has infected hundreds of people since 2003, mostly those who had worked with infected poultry. Its prevalence in the United States is not unexpected, with outbreaks previously reported in Asia, the Middle East and Europe.

Should humans be worried about being infected?

The risk to humans is very low, said Ron Kean, a faculty associate and extension specialist in the University of Wisconsin at Madison department of animal and dairy sciences.

“It’s not impossible for humans to get this virus, but it’s been pretty rare,” Professor Kean said.

In late April, health officials in Colorado said that tests detected the virus in a person who was working on a farm believed to have infected poultry. The person reported fatigue for a few days and has recovered, the C.D.C. said, adding that its risk assessment for the general public remained low.

Is it safe to eat poultry and eggs?

Yes, according to the U.S. Department of Agriculture, which has said that properly prepared and cooked poultry and eggs should not pose a risk to consumers.

The chance of infected poultry entering the food chain is “extremely low,” the agency has said. The Food Safety and Inspection Service, part of the U.S.D.A., is responsible for inspecting all poultry sold in interstate and foreign commerce.

Egg-production facilities that are subject to federal regulation are required to undergo daily inspections once per shift, according to the inspection service. State inspection programs, which inspect poultry products sold only within the state they were produced, are additionally monitored by the U.S.D.A.

Still, the U.S.D.A. recommends cooking poultry to an internal temperature of 165 Fahrenheit to reduce the potential for food-borne illness.

Can I expect to pay more for poultry products?

Egg prices soared when an outbreak ravaged the United States in 2014 and 2015. Recently, the average price of premium large white eggs has been “at record high levels,” according to an April 22 national retail report released by the U.S.D.A. If infections course through more flocks, experts said, there could be some shortages of eggs. Prices for white and dark chicken meat were also rising, according to the U.S.D.A. Experts also warned that turkey prices could also become more volatile.

How is the virus detected?

Testing for the avian flu typically involves swabbing the mouths and tracheal area of chickens and turkeys. The samples are sent to diagnostic labs to be analyzed.

Outbreaks have been detected in more than 2 dozen states.

As of April 20, the highly pathogenic form of the avian flu had been detected in 29 states, a tracking page maintained by the U.S.D.A. showed.

The combined number of birds in the infected flocks — the commercial and backyard type — totaled more than 33 million, according to the agency. A spokesman for the U.S.D.A. confirmed that those birds would be required to be euthanized to prevent the spread of the virus.

Two commercial egg production facilities in Iowa, one in Buena Vista County and another in Osceola County, constituted the largest infected flocks. Each was made up of more than 5 million chickens, the U.S.D.A. said.

The outbreak has taken an unusual toll on raptors or birds of prey, including more than three dozen bald eagles. Because spring is nesting season, some experts are worried that avian flu may pose a serious threat to the birds’ potential offspring.

In April, two cases of bird flu were confirmed in zoos in the United States, the Agriculture Department told The Associated Press, though a spokesman declined to give details or identify the zoos. Officials said they would not order the widespread euthanasia of zoo birds as they have on farms. Zoos in the United States began moving birds indoors, away from people and wildlife, to protect them from the bird flu.

How do these outbreaks compare to previous ones?

The outbreak in 2014 and 2015 in the United States was blamed for $3 billion in losses to the agricultural sector and was considered to be the most destructive in the nation’s history. Nearly 50 million birds died, either from the virus or from having to be culled, a majority of them in Iowa or Minnesota.

The footprint of the current outbreak, extending from the Midwest and Plains to northern New England, has raised concerns.

“I think we’re certainly seeing more geographic spread than what we saw with 2014-2015,” said Dr. Andrew Bowman, associate professor at Ohio State University’s College of Veterinary Medicine.

What can be done to stop the spread of the virus?

As early as last year, the U.S.D.A. warned of the likelihood of an outbreak of the avian flu and emphasized a hardening of “biosecurity” measures to protect flocks of chickens and turkeys.

Biosecurity measures include limiting access to the flocks and requiring farm workers to practice strict hygiene measures like wearing disposable boots and coveralls. Sharing of farm equipment, experts say, can contribute to spreading the virus. So can farm workers having contact with wild birds, including when hunting.

Experts at the University of Minnesota have also recommended that people stop using outdoor bird feeders and bird baths for a few months, until the rate of transmission decreases, to discourage birds from gathering.

“Not only will this action help to protect those beautiful feathered creatures that visit your yard, but will also help all wild bird species that are already having it hard this spring” because of the outbreak, Dr. Victoria Hall, executive director of the Raptor Center at the University of Minnesota, said in a statement.

Hummingbird feeders, which present a much lower risk, may be used but should be cleaned daily, the Raptor Center said.

Is it necessary to kill millions of chickens and turkeys?

Infected birds can experience complete paralysis, swelling around the eyes and twisting of the head and neck, according to the U.S.D.A. The virus is so contagious, experts say, that there is little choice but to cull infected flocks.

Methods include spraying chickens and turkeys with a foam that causes asphyxiation. In other cases, carbon dioxide is used to kill the birds, whose carcasses are often composted or placed in a landfill.

“It’s arguably more humane than letting them die from the virus,” Professor Kean said.

Isabella Grullón Paz contributed reporting.