The health authority in Jiangsu province said four people living in different cities are in critical condition after they developed fever, coughing and other symptoms around March 20. They tested positive for H7N9 on Tuesday afternoon.
Two men from Shanghai, aged 27 and 87, were confirmed dead on Sunday from H7N9 infection, with a woman from Anhui province in critical condition.
Hundreds of people who have had close contact with the patients have not, as yet, developed fever or respiratory symptoms.
Feng Zijian, director of emergency response at the Chinese Center for Disease Prevention andControl, said the country has launched a nationwide program to screen for H7N9 among patients with pneumonia, where the cause is unknown.
The program, supported by surveillance systems at public health institutions including hospitals, is aimed at timely detection of new cases.
To determine the source of the virus, the identities, background and living conditions of existing patients will be investigated, Feng said. “It’s unclear if the virus originated in pigs or other animals,” he added.
Sixteen top-level hospitals in Jiangsu have been designated as treatment sites for patients confirmed to have the virus, and all levels of hospitals are required to strengthen the screening of pneumonia patients against H7N9.
Other cities, including Shanghai and Beijing, have put forward plans to deal with emergencies or large-scale outbreaks caused by the relatively unknown strain of bird flu.
Shanghai authorities on Tuesday launched a yellow warning third-level emergency in response to the new strain.
Experts say the manufacture of a vaccine will take some time, as researchers will need athorough understanding of the virus.
Officials said poultry and pork for sale at local markets are safe, but people are urged not to eat wild poultry.
On Tuesday, Shanghai authorities reiterated that no bird flu virus had been found in dead pig samples from a river providing drinking water to residents.
In Beijing and Guangdong province, public health authorities said they are keeping a close eye on the H7N9 virus.
It is the first time the H7N9 bird flu virus has been found in humans, although three other strainsin the H7 family — H7N2, H7N3 and H7N7 — have previously been found in humans, but therewere no casualties.
BY WANYANG SHI