FIGHTING FOR LIFE: A 55-year-old poultry stall worker receives intensive care at a hospital in Bozhou, Anhui Province, on April 8, a day after being diagnosed with H7N9 (LIU JUNXI)

The unprecedented human infection with a former animal flu virus has touched a raw nerve among the public and posed a challenge to China's disease control system, which is quickly responding to a possible outbreak by drawing upon experiences from previous epidemics.

As an influenza A virus, H7N9 normally circulates among birds. However, the Chinese National Health and Family Planning Commission (NHFPC) confirmed the world's first three human cases on March 30, including an 87-year-old male and a 27-year-old male in Shanghai who both died from pneumonia symptoms in early March. A 35-year-old female in Anhui Province died on April 9.

According to the daily update of the NHFPC on April 10, the country has reported a total of 33 cases, including nine fatalities. On the same day, a four-year-old boy in Shanghai became the first H7N9 patient discharged from hospital.

A total of 15 cases, including five deaths, have been reported in Shanghai. Jiangsu Province and Anhui reported 10 cases with one death and two cases with one death, respectively. Six cases have been reported in Zhejiang Province, with two deaths.

The commission said that no epidemiological link between those cases had yet been identified and those who have had close contact with people infected by H7N9 have been placed under medical observation, but hadn't shown signs of infection.

The commission also said that the country's confirmed H7N9 cases remain isolated and there are no signs of human-to-human transmission.

All identified H7N9 patients show initial symptoms of fever and coughing, which develop into severe pneumonia in later stages.