NANNING, March 17 -- Four more human cases of H7N9 bird flu have been reported in south China's Guangxi Zhuang Autonomous Region, bringing the number of infections in the region to 17 this year, local authorities said Friday.

The new cases were reported Wednesday and Thursday. The patients, from the cities of Hechi and Liuzhou, are receiving treatment in hospital, according to the regional health and family planning commission.

Four fatalities have been reported in the region this year, so far.

H7N9 is a bird flu strain reported to have first infected humans in China in March 2013. Infections are most likely occur in winter and spring.