Avian flu in cattle: No cases in PA, but state authorities are taking precautions

An eight-state outbreak of avian influenza among cattle has captured national attention and raised concerns about the highly contagious virus spreading. But the virus so far has not reached Pennsylvania and does not appear to present a danger to humans, agricultural experts say.

The closest identified cases of the virus in cattle are in Ohio. Still, Pennsylvania and federal authorities are taking measures to contain the outbreak. Earlier this month, Pennsylvania required that cattle from states with avian flu cases get tested before they enter the state. And the federal government announced Wednesday that dairy cattle must now test negative for the virus before they are allowed to move between states.

Exposure to the virus is unlikely in Philadelphia, said Ernest Hovingh, the director of Pennsylvania State University’s Animal Diagnostic Laboratory.

“People are more likely to be exposed to a virus by wild birds flying over Philadelphia and potentially pooping on a picnic table,” he said.

Even then, cases are rare in humans, though they do occur, and in even more rare instances can cause severe illness and death, the CDC says.

Here’s a primer on highly pathogenic avian influenza, or HPAI, and the measures that Pennsylvania agricultural officials are taking to keep it out of the state.

Avian flu is a virus that typically spreads through wild birds, especially waterfowl. Wild birds generally show no signs of the virus even when they’re infected, but domestic birds can contract the virus through contact with wild birds or their droppings.

HPAI is an aggressive form of the disease that’s highly contagious, causes serious respiratory and digestive symptoms, like gasping for breath and diarrhea, in domestic birds, and can wipe out entire flocks. Usually, domestic flocks with HPAI are euthanized.

Avian flu has turned up in other animal populations, including mammals, in the past, Hovingh said. “It’s not really that surprising that other species can be infected with this,” he said.

What’s different about this outbreak is that herds are getting sick, not just individual animals. It’s unclear what’s caused the wider spread of the disease, Hovingh said.

Cattle are not as affected by avian flu as birds, Hovingh added. “It’s not a virus that really belongs in dairy cows,” he said. Symptoms among dairy cattle include eating less, producing less milk, and, occasionally, diarrhea or very dry manure. Most cows will recover within two to three weeks, he said.

Pennsylvania has seen cases of avian flu in birds for the last two years; in March 2023, the state had more birds with HPAI than anywhere else in the country. That outbreak has subsided in recent months, Hovingh said, but agriculture officials are still on high alert.

So far, Pennsylvania has seen no cases of avian flu in cattle. The closest confirmed cases emerged in Ohio and North Carolina.

“With most of these [infected] herds, so far, we’ve had a way to track the animals and the disease back to Texas, Kansas, or New Mexico, where this was first seen,” Hovingh said.

“It appears that this is coming to the other states from animals moving from the areas where it was first detected a couple months ago. That’s important, because that helps us as a state try to decide what we’re going to do.”

Pennsylvania required that cattle from affected states be tested for avian flu as well before they enter the state prior to this week’s federal directive requiring that cattle must test negative for HPAI before moving between states.

The state’s quarantine order, released earlier this month, also says animals from infected herds cannot move to Pennsylvania until their farm has been found to be free of the disease.

Farmers who believe their cows may be infected with avian flu should call the state Department of Agriculture, which has vets on call 24 hours a day, seven days a week, Hovingh said.

Penn State Extension, the university’s science education arm, is also on call 24/7 to examine flu tests from farms on an emergency basis, Hovingh said. “If we suspect [an outbreak of avian flu], we’re able to test for that very quickly,” he said.

The CDC has identified one case of a person getting infected with bird flu after being exposed to dairy cattle, and the agency says that bird flu spreading from person to person is very rare.

The agency recommends avoiding contact with animal feces, raw milk, and litter, as well as anything contaminated by animals with suspected or confirmed avian flu. The CDC’s experts monitoring the outbreak have also not noticed an unusual uptick in flu or flulike illnesses in humans.

The strain of avian flu infecting cattle has been found in raw milk, Hovingh said, although milk from animals who test positive for the virus is not being sold. On Tuesday, the federal Food and Drug Administration said it had found fragments of the virus in pasteurized milk but had no reason to believe the national milk supply is unsafe.

Pasteurization, the process that heats milk to a high temperature to kill viruses and other pathogens, likely also kills this strain of avian flu but may leave behind harmless particles of the virus, the FDA said in a statement.

Raw milk can be purchased in Pennsylvania, and sellers usually subject that milk to tests for bacteria — but not for HPAI, Hovingh said. “There’s probably virus getting into milk, but being killed by pasteurization — which is what it’s intended for,” he said. “Avoiding raw milk is generally a good idea.”