If bird flu is lurking undetected on Minnesota’s dairy farms, the state is determined to find it.
Starting in February, milk from each of Minnesota’s 1,625 permitted cow farms will test once a month for H5N1, the virus commonly called bird flu that began infecting cattle last spring.
Milk haulers already collect samples for routine testing while loading tankers at dairy farms, and portions of those raw milk samples will go to the Minnesota Veterinary Diagnostic Lab for H5N1 tests.
“We want to be fair, consistent and equitable, making sure that we’re treating Minnesota dairy herds the same, so that we’re not over-sampling some herds and under-sampling others,” said Nicole Neeser, director of dairy and meat inspection for the Minnesota Department of Agriculture, during a webinar introducing the testing plans last week. “Our program is efficient, meets our needs and … uses the systems we already have in place.”
Testing will continue for at least four months and become less regular if there is no evidence of H5N1, though efforts could ramp up if tests do detect the virus.
A positive result would not put the commercial milk supply at risk, because pasteurization inactivates the virus, according to the Food and Drug Administration. Outbreaks on dairy farms can put workers at risk of infection, however, and human exposure can help the virus mutate into a pandemic threat.
Minnesota has not reported a human case of bird flu. Nationally, one person has died from H5N1 and 67 have contracted it as of Friday. Of the positive human cases, 40 came from dairy herds.
“While most of these rare human infections have been mild, our biggest concern, because this virus is constantly changing, is that someone will be co-infected with a human seasonal influenza virus and an avian influenza virus,” said Dr. Stacy Holzbauer, an epidemiologist at the Minnesota Department of Health, on the webinar. “The genetic material of these viruses will go through a process that’s called re-assortment, creating a new influenza virus that could be easily transmitted from person to person.”
In poultry, the national bird flu outbreak began nearly three years ago and has claimed 145 million birds, including 8.8 million in Minnesota. The most recent case involved 79,500 turkeys in Dakota County on Jan. 15. Wild birds are the main source of transmission between farms, though recent Minnesota poultry infections have traced back to strains found in cattle, according to a state agriculture department document.
There were nine infected cattle herds this summer in Minnesota, according to the state Board of Animal Health. There hasn’t been a positive result reported since July.
“I’m under no illusion that there were no more cases than that,” Katie Cornille, a senior veterinarian at the Board of Animal Health, said during the testing webinar.
Unlike with poultry — which quickly die from bird flu or farmers can euthanize them to prevent spread — cattle recover from H5N1 infections. That puts less pressure on farms to find and report the virus, although infected herds need quarantining after a positive test result. There is a voluntary health monitoring program for dairy workers exposed to infected cattle.
The segmented structure of the dairy industry has also meant a less coordinated response and the possibility of undetected outbreaks compared to poultry, according to Michelle Kromm, a veterinarian, industry consultant and former vice president of animal health and welfare at Jennie-O Turkey Store. Companies that will slaughter, process and market turkeys and chickens typically own the birds, meaning the company’s assigned veterinarian has final say on farms where the birds are raised.
“For my dairy counterparts, the clients pay their bills, and so if the clients don’t want you to do something, you’re in a really tough spot from an income standpoint,” she said. “That includes talking to workers about the risk factors, reporting cases of conjunctivitis to MDH, potentially even reporting sick cows.”
Federal assistance for H5N1-infected dairy farms is also different from poultry, said Lucas Sjostrom, executive director of the Minnesota Milk Producers Association, during last week’s webinar.
“Not all help is available as advertised,” he said. “Nobody’s choosing to do wrong. Everyone’s just following the laws, and we’re kind of caught in this trap in dairy that poultry doesn’t have.”