HARRISBURG (TNS) — A fifth farm in Lancaster County has been impacted by the highly-contagious strain of avian influenza, according to the U.S. Department of Agriculture.

Nearly 307,400 birds at a commercial table egg laying operation were destroyed due to the virus or related depopulation, according to the USDA website.

An additional 3.5 million birds have been affected at four facilities, all of them in Lancaster County.

The state’s first positive case in poultry was detected on April 15 at a farm in East Donegal Township, which is home to nearly 1,700 of Pennsylvania’s more than 10,300 poultry operations. The farm euthanized 1.4 million chickens in response to the detection.

The Pennsylvania Department of Agriculture has said avian influenza poses no risk to the public. However, Agriculture Secretary Russell Redding said Monday that the need to stay vigilant is a priority not only for the poultry farmers but for food supply issues as well.

Avian flu is spread from wild migratory birds. The Pennsylvania Game Commission in late March reported the first detection of the disease in Pennsylvania, in a wild bald eagle found dead in East Marlborough Township, Chester County.

Despite the spread of the avian flu at poultry facilities, the state Department of Agriculture has said chicken and other poultry products remain safe to eat.