LANSING, Mich. – Dairy herds are now being affected by highly-pathogenic avian influenza (HPAI). While the first detections of the disease in cattle happened in Texas, it has now been detected in Michigan and Ohio according to the USDA. Both the FDA and USDA say there are no concerns with the safety of the commercial milk supply because products are pasteurized before entering the market. Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted or destroyed so that it does not enter the human food supply.

As of press time HPAI has been confirmed in seven dairy herds in Texas, two in Kansas, one in Idaho, one in Michigan, and one in New Mexico, and one in Ohio.

On April 3, the Ohio Department of Agriculture received confirmation of HPAI in a Wood County, Ohio, dairy cattle herd. Tim Boring, Michigan Department of Agriculture and Rural Development director, announced March 29 the detection of the virus in a dairy herd from Montcalm County, Mich.

Both herds had received cattle from Texas dairy herds prior to their outbreaks. 

The USDA’s National Veterinary Services Laboratories said it confirmed the strain of the virus found in Michigan is very similar to the strain confirmed in Texas and Kansas that appears to have been introduced by wild birds.

“Our highest priorities at the Michigan Department of Agriculture and Rural Development remain protecting our food supply and ensuring animal health,” Boring said.

On April 2, Tennessee’s State Veterinarian Samantha Beaty ordered a movement restriction on dairy cattle coming to the state from the affected premises. The order will expire May 3 unless it’s extended or rescinded.

According to the USDA, HPAI is a highly contagious virus that can be spread directly by infected wild birds/animals or indirectly through any item that has been exposed to the virus, such as equipment, feed, or the clothing and shoes of caretakers.

Jennifer Holton, Michigan Department of Agriculture and Rural Development communications director, told Farm World, “The Michigan Department of Agriculture and Rural Development continues to urge farmers and producers to implement, follow and heighten biosecurity measures to protect the health of their animals. Reducing the potential risk for introducing HPAI is paramount.”

In dairy cows, the illness causes decreased milk production, low appetite, changes in manure consistency, thickened milk, and low-grade fever.

On April 1, the CDC confirmed a person in Texas tested positive for HPAI following exposure to affected cattle; the individual’s illness is mild, and they are recovering. This is only the second case of H5N1 bird flu in the United States; the first was in a poultry worker in Colorado in 2022.

The CDC added the person in Texas worked with dairy cows and stated this would  be the first instance of cow-to-human spread of bird flu. The USDA, however, said initial testing has not found changes to the virus that would make it more transmissible to humans.

Denise Derrer Spears, Indiana State Board of Animal Health public information director, told Farm World, “Currently, Indiana has no known cases of HPAI in cattle. The Indiana State Board of Animal Health has been communicating with producers and veterinarians about biosecurity and prevention steps.

“The board has advised producers to be vigilant in watching for the main clinical signs and, if recognized, contact the herd veterinarian for testing,” she added. “The board has not made any changes to import or movement requirements for cattle.”

Matt Ernst, state veterinarian at the Illinois Department of Agriculture, told Farm World, “The detection of highly-pathogenic avian influenza in dairy cattle is a rapidly evolving event.

“The Illinois Department of Agriculture has not received any reports of suspected cases in dairy herds in the state,” he said. “We continue to encourage dairy producers to closely monitor their herds for signs of disease in individual animals and the herd as a whole.”

He said good biosecurity practices are an important component of livestock management: “We continually stress the need for on-the-farm biosecurity plans for each operation. When new stock is obtained, the animals need to be strictly isolated away from resident animals and monitored for signs of disease. A 30-day isolation period is a good rule of thumb.”

Steve Velasco, state veterinarian at the Kentucky Department of Agriculture, told Farm World, “At the Kentucky Department of Agriculture, we are monitoring the situation of HPAI detected in dairy cattle very closely. We are recommending heightened biosecurity measures at all dairies in Kentucky.

“Dairy cattle originating from states with affected herds as described on our website shall require a Kentucky Department of Agriculture Office of State Veterinarian-issued permit prior to movement into the Commonwealth of Kentucky until further notice,” he added. “Our goal is to protect our livestock and our agriculture industry will remain a top priority.”

The FDA said pasteurization has continually proven to inactivate bacteria and viruses, like influenza, in milk. The FDA’s longstanding position is that unpasteurized, raw milk can harbor dangerous microorganisms that can pose serious health risks to consumers.

The FDA is reminding consumers of the risks associated with raw milk consumption in light of the HPAI detections. Pasteurization is required for any milk entering interstate commerce for human consumption.

The USDA’s Animal & Plant Health Inspection Service said anyone working directly with cattle that have tested positive or fit the case profile and experience flu-like symptoms, should consult their physician. Human cases of influenza must be confirmed with testing; they cannot be diagnosed based on symptoms alone.

At this time, impacted herds do not appear to be experiencing mortalities associated with this disease syndrome, the USDA said. In impacted herds, approximately 10 percent of cattle are affected, with most cases being mid- to late-lactation mature cows.

The USDA added that impacted herds are experiencing an approximately 10 to 20 percent reduction in milk production for a 14- to 21-day period. Currently, dry cows, fresh cows, heifers and calves do not appear to be affected.