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 Friday.

The virus has wiped out more than 156 million chickens, turkeys and other birds nationwide since an outbreak in poultry began in 2022. Losses of laying hens have slashed egg supplies, sending prices soaring and prompting restaurants to raise prices.

Bird flu has also infected about two-thirds of the dairy herds in California, the biggest milk-producing state, and nearly 70 people since April.

In New York state, the five-day closure of live poultry markets in New York City and three counties—Westchester, Suffolk and Nassau—will allow them to be cleaned and disinfected to help prevent spread of the disease, New York Governor Kathy Hochul said in a statement.

Authorities found avian flu at markets in Queens, the Bronx, and Brooklyn since Jan. 31, according to the statement.

"I have directed our state agencies to use all available resources to ensure we are taking every measure necessary to keep the risk to the public low," Hochul said.

Wild birds often carry the virus during migration periods and can transmit it to poultry through direct contact or through contaminated feces or feathers. To contain the virus, poultry are culled when even one bird in a flock tests positive.

The U.S. Department of Agriculture for the first time this week confirmed a second strain of bird flu in U.S. dairy cattle, a discovery that ramped up concerns about its spread.