HEFEI, March 5 -- Another human H7N9 case has been reported in east China's Anhui Province, raising its total infections to six this year, local health authorities said on Thursday.

A 68-year-old poultry farmer in Chizhou City was diagnosed with the disease on Wednesday, the provincial health and family planning commission said.

The man and another five infected with the disease are all in critical condition, according to the commission.

H7N9 is a bird flu strain first reported to have infected humans in March 2013. It most often strikes in winter and spring.

Human cases of H7N9 have been reported this winter in several other Chinese localities including Guangdong, Shanghai, Fujian, Jiangxi, Guizhou and Zhejiang.