The Chinese Center for Disease Control and Prevention (CDC) said on April 10 that testing reagents for the H7N9 avian influenza virus have been distributed to all flu monitoring sites across the country and it also provided major infectious disease hospitals and research agencies with testing materials and detection methods.

The CDC said earlier that it is maintaining communication with health authorities in the United States and other countries and regions on relevant technological cooperation. It is also assessing the pandemic risks of H7N9 and working out coping strategies with relevant international experts.

The National Center for Food Safety Risk Assessment on April 7 urged preventive measures to ensure food safety, warning the public to avoid contact with potentially contaminated poultry.

The center also cautioned people to thoroughly cook eggs and poultry products, as it believes the virus cannot withstand high temperatures.

A laboratory under the Chinese Academy of Sciences (CAS) announced on April 10 that its researchers have ascribed the human infection to genetic reassortment of influenza strains caused by mingling of different bird populations during migration.

According to the researchers, the genetic reassortment is likely to have occurred in east China's Yangtze River Delta areas covering Shanghai, Zhejiang and Jiangsu, where a virus carried by migrating wild birds from the Republic of Korea and other regions in East Asia mingled with the avian influenza virus carried by local ducks and chickens.

Researchers also found that no H7N9 genes were traceable to pigs, thus excluding pigs as intermediate hosts for the deadly new strain of bird flu.

Both governments of Shanghai and Nanjing, capital city of Jiangsu, have suspended live poultry trade, shut down poultry markets temporarily and banned entry of live poultry from other parts of the country.

On April 4, the Shanghai Government ordered the culling of all birds in a live poultry trading zone of an agricultural products market after detecting the H7N9 bird flu virus in pigeon samples.

China's chief veterinarian Yu Kangzhen said on April 7 that infected poultry may show no symptoms at all of H7N9.

Yu told Xinhua News Agency on April 8 that H7N9 bird flu has not triggered an epidemic among poultry in China. Of the 738 samples collected from three live poultry markets in Shanghai on April 4 and 5, where the first known human deaths of the disease were reported, only 20 samples contained the H7N9 virus.

It was the first time the Ministry of Agriculture had detected the virus in animals in China.

Yu said that the possibility of infection among animals in other regions has not been ruled out and the Ministry of Agriculture has called for epidemic monitoring for animals across the nation and special attention to live poultry markets and poultry farms in affected areas. He pledged that the infected animals will be culled and their living environments will be disinfected in order to cut off the spread of the virus.