The Minnesota Board of Animal Health has quarantined a Stearns County dairy herd after samples collected as part of the state’s milk surveillance plan tested positive for H5N1, a strain of highly pathogenic avian influenza. The U.S. Department of Agriculture’s National Veterinary Services Laboratories confirmed the results Friday.

The Stearns County detection is the first in a Minnesota dairy herd so far this year. The same 620-cow herd also tested positive last July. The first bird flu detection in Minnesota livestock involved a Benton County dairy herd last June.

The Board of Animal Health says there is no concern for the safety of the public milk supply, as all milk sold in stores is pasteurized to kill bacteria and viruses, and pasteurization has been shown to effectively eliminate active H5N1 virus present in milk.

The U.S. Centers for Disease Control and Prevention has counted 70 human cases in the U.S. and one death, a person in Louisiana. All the human cases so far were contracted from animals. There have been no reported human infections in Minnesota.

The Stearns County herd will be quarantined until testing indicates the milk is no longer infected. Dairy farms are always required to dispose of milk from sick animals to remove it from the milk supply. In addition to disposing of milk from sick cows and isolating them, the quarantine also requires the farm to have three consecutive negative milk tests to be released from quarantine.

“While under quarantine, the herd will be able to apply for movement permits for animals and animal products such as waste milk and manure. Milk sold for pasteurization does not need a permit and is allowed to go to processing to facilitate business while keeping the risk of the spread of disease low,” said State Veterinarian Dr. Brian Hoefs. “Our surveillance and response approach to H5N1 is a team effort to ensure we’re covering all angles where it’s detected and limiting its ability to spread.”

Avian flu can cause reduced milk production in dairy cattle but is rarely fatal for cattle. However, it can spread from cattle to poultry, where it is highly deadly. Minnesota has had far more cases of avian influenza in poultry — mostly in commercial turkeys. Nearby states have seen heavy losses in commercial egg-laying flocks, which has caused tight supplies of eggs in many parts of the country.

The Minnesota Department of Agriculture is now testing pre-pasteurized, or raw, cow milk samples already collected from each of Minnesota’s approximately 1,600 dairy farms on a monthly basis. These routinely collected bulk milk samples, which are taken before the pasteurization process, are subsampled by industry labs and sent for H5N1 testing to the Minnesota Veterinary Diagnostic Laboratory at the University of Minnesota.

The H5N1 testing is part of a five-stage National Milk Testing Strategy being implemented across the country by the USDA’s Animal and Plant Health Inspection Service.

“Identifying which dairy herds are infected is important so we can prevent disease spread and protect both animal and human health,” said Minnesota Agriculture Commissioner Thom Petersen. “Regular sampling and testing will allow the MDA and partners to identify where the virus is present, monitor trends, and prevent spread of the virus in order to protect unaffected dairy herds and poultry flocks.”

The Board of Animal Health is notified of any preliminary detections of the virus in samples and responds by sending a case manager to the affected farm to issue a quarantine and guide the producer through the entire response process. The Minnesota Department of Health also monitors the health of people who have direct contact with infected animals or their environment and provides public health recommendations to help reduce the risk of infection.

The state Agriculture Department also provides testing, antivirals and personal protective equipment as needed. The risk to the public from this virus remains low at this time. People who work with or have direct contact with infected animals or their environment are at most risk for getting sick.

Dairy farmers should monitor their herd and contact their veterinarian immediately if cows appear sick. H5N1 symptoms in dairy mostly affect late-stage lactating cows and include fever, a drop in milk production, loss of appetite and changes in manure consistency.

Biosecurity reduces the risk of disease spreading onto or off farms. Measures to follow include keeping a log of farm visitors and ensuring they follow farm protocols; milking any sick cows last after the healthy herd; keeping feed covered and cleaning up feed spills immediately; and providing cows with a clean source of water away from wildlife, especially waterfowl.

Farmers can request a one-time distribution of PPE from the Agriculture Department if they’re unable to get it through their regular sources. People who have questions about avian influenza and human health can contact the department at 651-201-5414.

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