BEIJING - Four new cases of H7N9 bird flu were confirmed on Thursday in Shanghai and the provinces of Jiangsu and Zhejiang, according to local authorities.

A 26-year-old woman surnamed Wang from Jiangsu's capital of Nanjing was confirmed to be infected on Thursday. Five people who were in close contact with her have not shown flu symptoms.

Two other cases were confirmed in neighboring Zhejiang, according to the provincial health department. A 54-year-old woman surnamed Shen and a 69-year-old man surnamed Xu tested positive for the new strain of avian influenza. Both are in serious condition.

A Shanghai woman surnamed Ma also tested positive for the virus on Thursday, according to a statement issued by the Shanghai Municipal Health and Family Planning Commission.

Of the seven people who had been in close contact with Ma, none have exhibited any abnormal symptoms.

Meanwhile, an H7N9 patient surnamed Yang was discharged from a hospital at 2 pm Thursday after being successfully treated, according to the commission.

The 66-year-old Shanghai man showed flu symptoms on March 31 and was confirmed to be infected on April 6. Doctors said he now carries antibodies against the virus and will not be infected again.

China has reported a total of 87 cases of H7N9, of which 17 have died.