The number of H7N9 human cases in south China's Guangdong Province has reached 43 this year with one more case reported, provincial health authorities said when a 33-year-old man in Shantou city was confirmed infected. His condition is critical.
Guangdong is in the high-incidence period for bird flu, which occurs in winter and spring.
Thousands of chickens have been culled in Guangdong and Hong Kong this year. Several cities in Guangdong have taken measures to restrict the live poultry trade.
In addition to Guangdong, Shanghai, Fujian, Jiangxi and Zhejiang in east China have all reported human cases of H7N9 this winter.
Health authorities in Zhejiang Province said on Tuesday that it has reported 21 human cases of H7N9 avian influenza infection this winter.
H7N9 is a bird flu strain first reported to have infected humans in March 2013.