Bird flu spreads to 3 more Michigan commercial dairy farms

The highly pathogenic avian flu has infected more Michigan dairy farms only three weeks after it first spread to cattle.

The Michigan Department of Agriculture and Rural Development announced Friday, April 12 the bird flu was detected in three commercial farms in Ionia, Isabella and Ottawa counties. This brings the total number of infected Michigan dairy herds to four after the flu was confirmed at a Montcalm County farm in late March.

An egg farm in Ionia County was also struck by the virus two weeks ago – impacting 4 million birds, federal data shows.

“What is happening with HPAI in Michigan mirrors what is happening in states across the country. This virus does not stop at county or state lines, which is why we must all be on high alert. This news is unfortunate and upsetting for our poultry and dairy farming families and communities,” said Michigan Department of Agriculture and Rural Development Director Tim Boring in a statement.

Related: Dairy cows from commercial Michigan farm infected with bird flu

More than 88 million birds have died since the highly pathogenic avian flu started spreading more than two years ago.

The virus only recently jumped to cattle when the U.S. Department of Agriculture reported on March 25 that the first dairy cows in Texas and Kansas were infected through wild birds. It has since been detected in dairy herds across eight states and one person who had contact with infected cattle in Texas.

State Veterinarian Dr. Nora Wineland estimated most of the infected Michigan farms have herds of 500 or more animals and one was “a little smaller.”

Michigan traced the infected Montcalm County herd back to Texas, but officials are still working to figure out how it spread to three more dairy farms and the state’s largest egg producer.

“As far as connection points, we’re still continuing to evaluate what possible transmission mechanisms might have been,” Boring said in a Friday press conference.

State and federal officials have emphasized the bird flu does not pose a risk to the commercial milk supply. Dairy farms are required to divert or destroy any milk from infected animals, and pasteurization requirements are also “proven to inactivate bacteria and viruses” in milk, according to the USDA.

“If animals are sick, they are not allowed to have that milk go into the bulk tank for sale,” Wineland said.

Related: A chicken started gasping for air. Three days later, more than 60 birds were dead.

Because the highly pathogenic avian flu is particularly deadly for chickens – carrying a 90% to 100% mortality rate – one infected bird means the U.S. Department of Agriculture requires the entire flock to be “depopulated,” or killed, to keep the flu from spreading.

In Michigan, more than 4 million birds at five commercial farms and 25 backyard flocks have been killed because of the virus.

Infected cattle do not need to be depopulated and will recover within seven to 10 days.

“The animals are not quarantined. We ask the herd to restrict movements and only move animals that are absolutely necessary to be moved,” Wineland said.

Related: A deadly bird flu raised egg prices. Michigan farms vigilantly protect flocks.

Michigan is asking farms to tighten their biosecurity measures because the avian flu can spread easily through wild birds or infected poultry, equipment, feed and on the clothing and shoes of farmers.

Farms should disinfect equipment, limit non-essential visitors, provide clean clothing to employees and monitor the health of animals daily. Employees should also wash their hands frequently.

“It continues to be vitally important for producers to work with their veterinarian, minimize the number of visitors to their farms, prevent contact between their animals and wildlife, and continue to monitor the health of animals vigilantly,” Wineland said.

The risk of humans getting sick from the avian flu remains low, according to the CDC, and no infected birds will enter the food chain.