The newly reported H5N9 strain was found Monday at a duck farm in Merced County, California, according to the World Organization for Animal Health. The Paris-based organization that studies animal diseases said it's the first verified U.S. case of H5N9 in poultry. The organization said the more common strain H5N1 was also found.

Six dead swans have been found in Worcester in a case of suspected bird flu. Worcester City Council said on Tuesday evening the birds had been found along a stretch of the River Severn between the cathedral and the railway viaduct. It added that some parts of the riverside path had been closed to help reduce the spread.