FUZHOU, Jan. 16 -- Four new cases of human infection of H7N9 bird flu were reported in east China's Zhejiang and Fujian provinces on Thursday, according to provincial health authorities.

The cases involve a 30-year-old man surnamed Zeng and a 60-year-old man surnamed Xu. Both are seriously ill and receiving treatment in the city of Quanzhou, Fujian.

The two other cases are a 20-year-old woman and a 58-year-old man in Zhejiang Province. Both are in serious conditions and receiving treatment in the cities of Hangzhou and Taizhou respectively.

The total number of cases reported in Zhejiang is 14 so far this year.

In 2014, human contractions of H7N9 have also been reported in the provinces of Jiangsu and Guangdong, as well as the city of Shanghai. A suspected case was also reported in southwest China's Guizhou Province on Monday.