Dairy and poultry farms in California and 15 other states have been devastated by the recent avian influenza outbreak. But in Pennsylvania, dairy farms have so far been spared from the virus rocking the U.S. agriculture industry.
“Currently there are no infected farms in Pennsylvania… we do not have [avian influenza] in our cattle or our birds,” said Dr. Alex Hamberg, Pennsylvania’s state veterinarian and director of the bureau of animal health and diagnostic services. The state has required precautionary bulk milk testing since November for Pennsylvania's roughly 4,900 dairy farms. The bulk testing came weeks before the U.S. Department of Agriculture initiated a nationwide requirement this month.
Pennsylvania has seen positive cases of the highly pathogenic avian influenza (HPAI) at poultry farms since the state’s first case was detected in Lancaster County in 2022. The virus has killed millions of Pennsylvania birds as recently as this spring. But as of late last week, there are no confirmed cases at poultry or dairy farms in the commonwealth.
Hamberg said that Pennsylvania’s current dairy farm surveillance is a step up from its previous testing programs, which were voluntary. And initiating routine testing before a viral outbreak happens can help the state act quickly to contain any threats.
“Getting that surveillance data is really critical to making sure that we can protect our dairy farms and protect our poultry,” Hamberg said.
In a statement, Turner Dairy Farms stressed the important role regular testing plays in product safety. The major milk producer, located in Penn Hills, submitted to voluntary testing months before the state made the practice mandatory.
“Without that knowledge we cannot take appropriate action to prevent the spread to neighboring farms,” said Turner Dairy Farms president Chuck Turner. “We feel we have a responsibility to our family dairy partners, employees and consumers to do the right thing to ensure safety and mitigate negative impacts to the industry.”
Pennsylvania was also ahead of the USDA this spring when it initiated a quarantine order that required testing of dairy cattle arriving from out of state. Pennsylvania borders Ohio where cows shipped up from Texas tested positive for bird flu in March. The USDA implemented a nationwide cattle testing program a month later.
Hamberg said the state’s proactive approach reflects the kind of destructive impact an outbreak could have on Pennsylvania’s nearly $133 billion agriculture industry. If infected livestock came into the state, the virus could spread rapidly due to how many farms are situated near one another.
“One of the things that makes Pennsylvania very unique is that we've got a lot of dairy farms in very close proximity to poultry farms, and we've got a lot of both,” Hamberg said.
The new USDA requirements for dairy producers issued this month won’t change the procedure already in place in Pennsylvania, according to Hamberg. Milk tanker trucks take raw milk from dairy farms to processing plants where the supply is tested at least once every two weeks. Samples are then sent to one of the state’s animal diagnostic labs — either Penn State University or the University of Pennsylvania — for testing.
Testing raw milk provides a better chance of detecting the virus, Hamberg said, because milk carries higher viral loads that can remain active at low temperatures for weeks.
A positive sample from a dairy farm would trigger a mandatory quarantine for all dairy farms within a 1.86-mile radius and weekly samples from all farms in the affected zone. But according to the state’s Department of Agriculture, such a lockdown has not yet been required.
Since the sampling happens before processing, the state is able to ensure the safety of dairy products other than milk like cheese, yogurt and sour cream. But Hamberg stresses: "pasteurization procedures in the U.S. eliminate the threat of the virus to humans." If traces of HPAI are detected in raw milk, the pasteurization process would inactivate the virus.
“What we're worried about here is an animal health problem, and we want to make sure that if we do have it in Pennsylvania, we can detect it early so that we can protect our cows and we can protect our birds,” Hamberg said. Most cows recover from cases of avian influenza. But as the disease spreads among cattle, it could sicken and kill more birds.
Still, about 900 people have been infected with an avian influenza virus over the last 20 years, according to the National Institutes of Health. Though the Centers for Disease Control and Prevention have detected sporadic human cases resulting from contact with dairy cows, most people got sick after close contact with infected birds. The virus has not spread effectively from human to human, which limits any potential threat of a pandemic, according to the NIH.
Though pasteurization greatly limits the risk of infected dairy products to humans, The Food and Drug Administration is warning people against consuming raw dairy products such as raw milk, which can harbor active avian flu virus for more than a month. The FDA said unpasteurized milk can also carry bacteria such as Salmonella, E. coli and Listeria.
Hamberg said though pasteurization is a proven public health measure, he knows some dairy consumers prefer raw products.
“Some folks want to have access to those raw milk products,” Hamberg said. “That’s a calculated risk that those individuals are going to have to take.”
