The National Health and Family Planning Commission, which summoned a meeting of health officials and experts from municipalities and provinces where the cases have been reported, said it instructed them to strengthen prevention and control work against the H7N9 epidemic.
On Wednesday, China reported four more human cases of H7N9 avian flu, raising the alert on the epidemic in the country, the official Xinhua News Agency reported. One of the new cases was a 71-year-old man from the eastern province of Jiangsu, who remained in critical condition.
Earlier this week, Chinese health authorities reported the deaths of two men, including a 31-year-old doctor, from H7N9 in Shanghai. The other victim was a 77-year-old farmer. Xinhua said both men had tested positive for the H7N9 virus posthumously.
In the case of the doctor, the Shanghai health commission said none of the people who had close contacts with him, including his colleagues and his patients, had shown any flu symptoms such as fever and coughing. The doctor also had no close contacts with flu patients in the 10 days prior to becoming ill.
Details about the 77-year-old man were not available.
On Monday, the United Nation's Food and Agriculture Organization in Rome said humans infected by the H7N9 virus are on the rise again in China and warned the upcoming Chinese New Year festivities could lead to further spread and human exposure when millions of poultry would be consumed.
The agency called on China's neighboring countries to remain vigilant against H7N9 and other avian influenza viruses, such as highly pathogenic H5N1.
The FAO, citing the World Health Organization, said the number of human infections with H7N9 has increased since late December in east and southeast China, noting the increase was expected as flu viruses traditionally show increased activity during winter months.
China's national health agency said over 40 human cases of H7N9 have been reported so far this year in Shanghai, Jiangsu, Fujian, Zhejiang and Guangdong provinces. The agency said it has strengthened coordination with the agriculture ministry and the China Food and Drug Administration to control H7N9.
The agency also said the current cases are scattered, and no mutation of the virus had been identified so far that could affect public health, Xinhua reported.
FAO's chief veterinary officer Juan Lubroth said Chinese authorities are enforcing important measures to reduce the risk of human exposure, including temporary closures of live bird markets, regular market rest days, improved hygiene in markets and control of poultry movements.
"But countries need to stay alert, as the virus continues to circulate in poultry without showing any visible clinical signs. The risk to humans remains, especially over the next few months and particularly during the Chinese New Year's holiday period," Lubroth said.