Bird flu continues to spread across the country, with the virus wiping out wild bird populations and devastating poultry farms. This week, dairy cattle in the U.S. tested positive for a strain of bird flu that had not been seen in cows.

Authorities in New York state have temporarily closed all live poultry markets in New York City and three suburban counties after bird flu was detected at seven markets within the past week, according to a notice on the state's website.

While the risk to humans of exposure from cows or milk remains low, this new flu spillover from birds into cows raises the need for continued surveillance.