HPAI continues to spread in dairy cattle

Nearly three months ago, the first cases of Highly Pathogenic Avian Influenza H5N1 in dairy cattle was confirmed by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service. Since then, the virus has continued to spread, affecting dairy cattle across the country.

This month, documented confirmed cases in Iowa, Minnesota and Wyoming bring the total number of confirmed cases to 102 herds in 12 states as of June 18. Illness among three dairy farm workers — one from Texas and two from Michigan — have been confirmed after exposure to infected dairy cattle.

The spread of H5N1 between states has been linked to the movement of lactating dairy cattle. This prompted the Federal Order that went into effect April 29 requiring lactating dairy cattle to have a negative test within seven days of crossing state lines. Epidemiological evidence suggests that further local spread is likely multi-factorial, through both direct and indirect transmission routes.

A national epidemiological brief posted June 13 on the APHIS website, which detailed information collected from 54% of affected premises as of June 8, said that more than 20% of affected farms brought animals into the herd within 30 days of the initial observation of clinical symptoms. More than 60% of farms continued to move animals off the farm after the onset of those clinical signs.

The level of impact the disease has had on affected farms varies greatly. The most prevalent clinical signs observed in dairy cattle include milk that appears abnormal and a decrease in production, feed consumption and rumination. Cows frequently exhibit fevers and dehydration.

Other clinical symptoms reported include respiratory issues such as increased respiratory rates, labored breathing, nasal discharge and pneumonia.

Due to that evidence, researchers recommend dairy farms develop and enforce strict biosecurity protocols as a measure to help mitigate the risk of the virus reaching their herds. While enhanced biosecurity is a measure to prevent the spread of disease, the summer fair and show season adds another layer to the issue.

On June 11, during a press call, Wisconsin Secretary of Agriculture Randy Romanski announced a new testing order put in place by the Wisconsin Department of Agriculture, Trade and Consumer Protection. He said it continues to be an evolving situation.

“With an increasing number of affected states and a busy fair season ahead of us, DATCP is acting within our regulatory authority to try and minimize the risk of commingling potentially sick animals,” Romanski said.

The order, which went into effect June 19, requires all lactating dairy cattle moving within the state for purposes of show or exhibition to have a negative H5N1 test within seven days before movement.

“We have been monitoring the increase in cases, especially in the upper Midwest,” said Wisconsin State Veterinarian Dr. Darlene Konkle. “With the increasing number of cases in our region, it made sense to minimize the opportunities for the virus to be introduced or spread in Wisconsin, particularly if animals are moving to fairs and exhibitions.”

Konkle said the purpose of the order is to protect not only the dairy industry in Wisconsin, but poultry and other livestock industries as well.

“We know the virus can spread cow to cow and also from cattle to poultry and poultry to cattle,” Konkle said. “We know that lactating dairy cattle are potentially the highest risk of spreading large amounts of the virus, but we also know that lactating dairy cattle and other classes of cattle could be affected without showing clinical signs.”

On June 13, the Minnesota Board of Animal Health issued an order effective June 18 that requires a negative test and a certificate of veterinary inspection for all lactating animals before in-state movement for all exhibitions.

Both the Wisconsin and Minnesota orders require testing at National Animal Health Laboratory Network facilities, with samples being collected within seven days of movement. While the testing is run at no charge to producers, funds are available through the USDA to help cover veterinarian and shipping costs associated with testing.

Konkle said that the Wisconsin Veterinary Diagnostic Laboratory is running tests Mondays, Wednesdays and Fridays. Samples that arrive at the laboratory on those days before 1:00 p.m. will be tested the same day. Samples arriving after 1 p.m. or on Tuesdays and Thursdays will be tested the next day tests are run.

The Minnesota order is in effect until the end of 2024, unless rescinded earlier. The Wisconsin order will remain in effect until 60 days after the last detection of H5N1 in cattle herds in the U.S.

Konkle and Romanski encourage exhibitors to follow the USDA’s recommendations for minimizing transmission at exhibitions which was published last month.

Exhibitors are encouraged to become familiar with signs of H5N1 in dairy cattle and to discuss the potential risks of exhibiting animals with their herd veterinarians.

To the greatest extent possible, an attempt should be made to limit the commingling of animals from different herds to reduce nose-to-nose contact.

Exhibitors should not share husbandry tools, feed and water, portable milking equipment or grooming supplies with other exhibitors. All equipment, including trailers, should be thoroughly cleaned and disinfected before leaving the farm and before returning to the farm. This protocol should also be frequently conducted during the show. Exhibitors should avoid transporting animals from different farms in the same trailer.

Animals returning to the farm from an exhibition should be isolated and observed before they come into contact with animals that did not leave the farm. It is also recommended that equipment not be shared between show animals and other animals at home.

“We wanted to get ahead of a busy show and fair season this summer,” Romanski said. “We have lots of dairy kids wanting to show. The way Dr. Konkle has structured this order, those kids will still have the opportunity to exhibit a cow at the fair — the only extra step is testing.”