Update: Dairy Farm Flu Outbreak

This article was originally posted at 4:46 p.m. CDT on Wednesday, June 5. It was updated at 11:07 a.m. CDT on Thursday, June 6, with information on a new report of H5N1 cases in a central Minnesota dairy herd.

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DES MOINES (DTN) -- Minnesota and Iowa now have each confirmed new cases of H5N1 avian influenza in dairy herds.

The Minnesota Board of Animal Health on Thursday reported that a dairy herd in Benton County, in central Minnesota, had tested positive.

"Over the weekend, the producer noticed clinical signs in only a handful of cows; the next day, more than 40 cows had signs of fever," Minnesota officials stated in a release.

"We knew it was only a matter of time before this detection would reach our doorstep," said Dr. Brian Hoefs, Minnesota's state veterinarian. "It's important for dairy farmers to follow the example of this herd and test sick cows. The more the animal health community can learn about this virus today through testing and research, the better we can equip ourselves to prevent infections tomorrow."

The Iowa Department of Agriculture and Land Stewardship reported on Wednesday a dairy herd had detected the H5N1 virus in O'Brien County, which is in the state's northwest corner.

With the Minnesota and Iowa herds, there are 86 dairies confirmed with infected cattle. There have been 18 dairy herds that have tested positive since May 30. The USDA webpage tracking H5N1 is typically a day or two behind state confirmations. Since Monday, USDA also has confirmed new illnesses in three more Texas dairies, as well as another dairy in Idaho.

The increase in reported infections was expected as USDA has encouraged more producers to voluntarily test their herds for the virus. Last week, USDA announced a pilot program that designates dairy farms as "negative status" that have tested negative for the virus three weeks in a row using "on-farm bulk milk" or similar milk samples. Herds that continue testing negative for the virus weekly from their bulk tanks will be allowed to move lactating cows across state lines without specifically testing those individual cows. Otherwise, dairy farmers still must test individual lactating cows for the virus before they can cross state lines.

Minnesota and Iowa officials stated final confirmatory testing of the confirmed infection is pending at the National Veterinary Services Laboratory (NVSL) in Ames, Iowa.

The Iowa Department of Agriculture stated it would soon be announcing additional response measures.

Iowa has already been plagued by the H5N1 virus hitting its poultry sector. Since the last week of May, Iowa has reported a 4.3 million head egg-laying operation and a 100,000-head commercial turkey operation tested positive for highly pathogenic avian influenza, forcing officials to depopulate both farms.

Iowa officials noted that genomic sequencing of the virus from the egg-laying farm in Sioux County, another northwestern county, was "consistent with the variant identified in affected dairies in other states."

The sequencing is not yet completed on the virus detected at a recent turkey flock in Cherokee County or the dairy farm in O'Brien County. Epidemiological investigations are ongoing to try to determine how the virus was introduced into the flocks and herd.

"Given the spread of Highly Pathogenic Avian Influenza within dairy cattle in many other states, it is not a surprise that we would have a case given the size of our dairy industry in Iowa," said Mike Naig, Iowa's secretary of agriculture.

While H5N1 is fatal to poultry, dairy cows typically have mild symptoms and recover in about two weeks, USDA officials have said.

Three dairy farmers -- one in Texas and two in Michigan -- have also tested positive for the H5N1 virus. The Centers for Disease Control has continued to try to convince dairy workers to be tested and to wear personal protective equipment (PPE). USDA also has offered incentives to dairy farms to use PPE equipment.

Testing has found inactive fragments of the virus in pasteurized milk. FDA has repeatedly said pasteurized milk does not pose a risk to contracting the virus. Unpasteurized milk, however, does pose a risk if it comes from a herd that could be infected with H5N1.

Dairies are required to dispose of milk from sick animals to remove it from the milk supply, as well as isolate sick cows from the rest of the herd. Sick cows should also be milked last, after the healthy cows have been milked. After 30 days from the last positive test, the herd can be retested to be released from quarantine, Minnesota officials stated.

USDA last week announced the release of $824 million to respond to the outbreak, including funds to develop a vaccine, and encourage more dairy farmers to test their milk for the virus.

Naig indicated his department is preparing to help cattle producers recover and will be announcing additional steps to protect flocks and herds.

"Poultry producers and dairy farmers should immediately take steps to harden their biosecurity defenses, limit unnecessary visitors, and report symptomatic birds or cattle to the Department. This remains an evolving situation and we will continue to be in close communication with stakeholders, USDA, and other states as we evaluate our response. Our top priority is to protect our livestock and the farmers and people who care for them."

Chris Clayton can be reached at Chris.Clayton@dtn.com

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