The U.S. Food and Drug Administration is warning retailers and restaurants not to sell certain oysters that could be contaminated with norovirus after 15 people became ill in Louisiana, U.S.A.

The Louisiana Department of Health closed an oyster harvesting area after 15 people reported norovirus-like illnesses.

The outbreak was reported late last month in southwest Alabama and left 11 people ill, including three who sought emergency room treatment.