TOKYO, Nov. 9 (Xinhua) -- Japan's environment ministry confirmed Thursday that a wild swan found dead in western Japan was infected with a highly pathogenic bird flu.
The dead swan was found near Lake Shinji in Matsue, Shimane Prefecture Sunday and tested positive for bird flu in a simple test.
Further tests at the Tottori University confirmed that the swan was infected with the highly pathogenic H5N6 influenza strain.
It was the first bird flu case confirmed in Japan this season, according to the ministry.
The environment ministry has since Sunday strengthened monitoring of wild birds within 10 kilometers of the place where the dead swan was found.
It also raised on Thursday the country's bird flu alert from one to two on a scale of three.
In March, hundreds of thousands of chicken at poultry farms were culled in Miyagi and Chiba prefectures due to the outbreak of a highly pathogenic bird flu.