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Experts provide bird flu facts to dairy producers

“With the current strain of the virus, there is no human-to-human transmission,” said Elisha Frye, assistant professor of practice in the Department of Population Medicine and Diagnostic Sciences (CVM) and diagnostic veterinarian at CVM’s Animal Health Diagnostic Center. “So that’s the good thing.”

Since 2022, two human cases of H5N1 have been reported in the US. The first was a Colorado prisoner who was depopulating poultry in 2022 and his only clinical symptom was fatigue. The other was a dairy farm worker who developed pink eye, or conjunctivitis, in April. Both recovered. Internationally, 13 human cases of H5N1 (clade 2.3.4.4b) have been documented through the Centers for Disease Control and Prevention, with one death, Frye said.

Infections in dairy cows, which may have initially contracted the virus from wild birds, have been confirmed in Colorado, Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota and Texas across 36 herds, said Joy Bennett, director of the NYSDAM Animal Industry Division.

The species has been found in many New York counties since February 2022 in backyard bird flocks, upland game birds and live poultry markets, Bennett said.

Regarding commercial dairy, the Food and Drug Administration recently collected nearly 300 samples of fluid milk, cottage cheese and sour cream from 38 states and tested them for H5N1, says Samuel Alcaine, associate professor of food sciences at CALS.

“About … one in five of these samples tested positive for fragments of the virus,” Alcaine said. Further testing showed that the virus found in all samples was inactivated thanks to pasteurization.

Now the U.S. Department of Agriculture is sampling ground beef from states where herds have currently tested positive; so far, the first 30 samples have all come back negative, Alcaine said.

It is unknown how well the virus survives in raw milk, which makes up a small portion of the dairy market, or what virus doses in milk would be needed to infect humans, he said.

“There are still many questions for raw milk cheesemakers about what to do if their cows test positive for bird flu,” Alcaine said. “They are absolutely not allowed to make any product from contaminated milk or potentially contaminated milk.”

He added that raw milk producers in states with positive herds should consider testing their bulk milk.

Tom Overton, professor of animal sciences and program director of PRO-DAIRY at CALS, moderated the event. Alan Bjerga, executive vice president of communications and industry relations at the National Milk Producers Association, was also a panelist.

The event was organized by the New York Farm Bureau (NYFB), the Northeast Dairy Producers Association (NEDPA) and CALS.