The National Avian Flu Reference Laboratory said Thursday that the new strain of bird flu, H7N9, has been found in two out of a total of 10 duck samples in Huzhou, Zhejiang Province.
The finding, which came after the virus was previously detected in chickens and pigeons, triggered a mass culling of some 7,000 live poultry in a key trading market in the city.
The live poultry trade in some 15 wet markets across the city has also been suspended after the finding.
The National Health and Family Planning Commission said that by late Thursday, the new strain of bird flu had killed 10 patients in the country, and there have been 38 infections detected, a figure that was brought up by the five new cases in Shanghai and Zhejiang Province Thursday.
The commission said those who had close contact with the infected patients have been placed under medical observation and have exhibited no abnormal symptoms.
The commission stated that all H7N9 cases are isolated and there was no epidemiological link between those cases that have been identified to date, adding that there have been no signs of human-to-human transmission.
In order to prevent the spread of the virus, regions including Shanghai, Jiangsu, Zhejiang and Anhui have taken measures to cull poultry and ban trade.
Shanghai has banned the poultry trade and imports from other regions, and also stopped the wild bird trading business in 162 enterprises.
At the West Lake scenic spot in Hangzhou, Zhejiang Province, captive bred birds, including swans, doves and peacocks, have been isolated by the management office. The office also warned tourists to stay away from birds around the lake, the Xinhua News Agency reported.
In other places where no H7N9 cases have been reported yet, such as Qingdao in Shandong Province and Taiyuan in Shanxi Province, the live poultry trade has also been banned as a preventive measure.
Zeng Guang, chief epidemiologist at the Chinese Center for Disease Control and Prevention, told the Global Times that it was still not certain that shutting down poultry businesses would be effective.
"There is still no solid research data showing that the ban of the live poultry trade has slowed the spread of the virus, though it might to some extent help contain cross-infection between poultry in some infected areas," Zeng said.
Zeng added that studies into the prevention of H7N9 are still in the very early stages.
The national commission stated on Wednesday that H7N9 was mainly spread through inhalation, while pointing out that people who are involved in the live poultry trade or slaughter have a high risk of becoming infected.
"Banning the trade and culling birds is only an expedient. Research into vaccines and effective medication are critical," Zeng said.