The ongoing U.S. outbreak of avian flu in dairy cattle reached Minnesota on Thursday as the state announced its first infected herd.

More than 80 dairy herds have been infected with the virus across 11 states since late March, and three dairy workers have tested positive for the virus.

The Minnesota Board of Animal Health said the farmer of the affected herd reported more than 40 cows with signs of fever. The animals were tested on Monday and the U.S. Department of Agriculture’s (USDA) National Veterinary Services Laboratories confirmed the positive test on Wednesday night.

The animals are recovering, said Brian Hoefs, the state veterinarian.

Milk from the sick cows was disposed of, and the state Board of Animal Health has quarantined the entire herd for 30 days to reduce the risk of the virus spreading off the farm, the agency said. After 30 days from the last positive test result, the herd can be retested to be released from quarantine, the agency added.

“We knew it was only a matter of time before this detection would reach our doorstep,” said Hoefs. “It’s important for dairy farmers to follow the example of this herd and test sick cows.”

This was not the first Minnesota dairy farm tested for avian flu due to cattle showing signs of illness, but it was the first to confirm positive results, Hoefs said.

More samples from dairy farms could be sent to the state lab in the coming days, he said.

“Once this news gets out, then it kind of triggers other farms to consider doing the testing if they were on the fence prior,” Hoefs said. “My guess is we will see more testing later this week into next week.”

The other states that have reported infected herds so far are Colorado, Idaho, Iowa, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota and Texas.

Dairy cows with avian flu have died or been slaughtered by farmers after not recovering, Reuters reporting found. The USDA said that the vast majority of cows recover from the illness.

—P.J. Huffstutter and Leah Douglas, Reuters