PA Leads Nation In New Bird Flu Cases Amid Historic Outbreak

PENNSYLVANIA — The highly infectious avian influenza that had already claimed the lives of millions of birds before this year is spreading again at a rapid rate, and Pennsylvania is by far the hardest hit state, according to the latest statistics.

It's the largest outbreak of bird flu in American history, with the 58.62 million birds killed far surpassing the 50 million killed during the 2015 outbreak.

Within the past month alone, Pennsylvania has seen 23 separate outbreaks that have killed 215,340 birds, according to U.S. Department of Agriculture data. That includes 4 commercial flocks and 19 backyard flocks.

That includes 6 outbreaks on Lancaster County farms on March 13 and March 14 alone, officials said. Some 17,000 birds were killed on those two days.

Farms in Bucks, Chester, Tioga, and Allegheny counties have also seen mass mortality events this year.

Other states like Florida and Virginia have dozens or hundreds of cases, but none have anywhere close to the outbreak Pennsylvania is experiencing. Part of the reason for that is because Pennsylvania is such an important stopover for migratory birds, scientists say, increasing contact between flocks and making it more likely the flu is spread swiftly here.

The common wisdom runs that the risk is low for humans to catch the disease. But the World Health Organization (WHO) urged caution and preparatory steps during a February summit.

"We cannot assume that will remain the case and we must prepare for any change in the status quo," Dr. Tedros Adhanom Ghebreyesus, the WHO Director General said during a press briefing.

Bird flu does impact other species. It's been detected with some regularity this year in mammals like otters, skunks, and mountain lions. And the New York Times reported this week that there's an outbreak among seals in New England.

Another factor fueling bird flu in Pennsylvania and nationwide is the changing climate. Climate impacts migration patterns for all species, including birds. This year is the warmest winter on record, and birds that normally would not be moving around this time of year suddenly think it's time to fly north.

This impacts the availability of breeding sites — sites which in many cases are already limited by overdevelopment and other human impacts — which can cause overcrowding and higher than usual interaction between domestic birds and migratory birds. This fuels the spread of the disease, according to recent research published in the Journal of Climate Change and Health.

The highly contagious and fatal disease hits domestic poultry the hardest. Impacted species include chickens, ducks, geese, turkeys, guinea fowl, quail, pheasants, emus and ostriches. Wild species also can pick up the flu, as the flu was first detected in the state in a wild bald eagle in East Marlborough, Chester County, in March 2022.

Mass euthanasia is the typical first response of state responders. Agriculture officials continue to urge farmers to install enhanced biosecurity measures to protect their flocks.