Four new infections of H7N9 avian flu were reported in east China´s Zhejiang Province on Sunday, bringing the total number of such cases in China to 55.

The patients include two from the city of Huzhou and one from the city of Hangzhou. The fourth patient is suspected of acquiring his infection after traveling to the city of Wenzhou.

All four patients tested positive for H7N9 at the Zhejiang Provincial Disease Prevention and Control Center on Sunday, according to a statement from the provincial health department.

All four patients are in serious condition, the statement said.