As authorities launched a nationwide screening campaign for the H7N9 virus, health officials said four more people living in different cities in east China's Jiangsu province have been confirmed to be infected with the flu strain, China Daily reported. All four were infected around March 20, and remained in critical condition Wednesday.
The four include three women, ages 32, 45 and 48, while the fourth is an 83-year-old man, the report said. All are reported to be the first such cases of human infection from H7N9.
Last Sunday, health officials said two men in Shanghai, ages 27 and 87, died of the same H7N9 infection. In the third such case, a 35-year-old woman from eastern Anhui province remained in critical condition, the report said.
Provincial health experts said no epidemiological links have been found among the four new cases, and that hundreds of people who have had close contact with them have so far not developed fever or respiratory symptoms.
A health report said only the 45-year-old woman, who works as a poultry butcher in Nanjing, has been in close contact with poultry.
Feng Zijian at the Chinese Center for Disease Prevention and Control said a nationwide program has begun to screen for H7N9 among those with pneumonia, the cause of which has not been determined.
The report said major cities including Shanghai and Beijing have drawn up plans to deal with emergencies or large-scale outbreaks caused by the relatively unknown strain of bird flu.
Earlier, health officials ruled out the avian flu strain blamed in the deaths of two men in Shanghai came from dead pigs found in a river in the city which provides drinking water to residents.
A health report said H7N9 bird flu virus shows no signs of being highly contagious among humans and there are no vaccines against it anywhere as not much research has been done on the virus.
However, another strain of avian flu, H5N1, has reportedly led to hundreds of deaths since 2003 and has killed millions of birds.
The World Health Organization has been informed about the flu cases