Chinese scientists' findings about the potential origins of H7N9, the novel strain of bird flu that has killed more than 20 people in the country, were published by the online issue of The Lancet on May 1.

Scientists from the Chinese Academy of Sciences, the Chinese Center for Disease Control and Prevention, and universities, found that H7N9 was reassorted from influenza viruses of at least four different origins.

One of the virus's genes might have originated from avian influenza viruses among ducks in China's Yangtze River Delta region, where the epidemic broke out.

Another gene might have evolved from migratory birds passing the country, and ducks might have acted as a leading intermediate host, transferring viruses of wild birds to domestic poultry, according to the findings.

Moreover, the six internal genes of this virus probably originated from two different groups of H9N2 avian influenza viruses, respectively traced to the east China provinces of Jiangsu and Zhejiang, as well as Shanghai.

Meanwhile, H7N9 has evolved into at least two different lineages, showing different patterns of drug resistance to Tamiflu, an anti-flu medicine, the scientists found.

Since H7N9 was first identified on March 30, 127 cases have been detected in 10 provincial regions, and the virus has killed 26 people in the Chinese mainland, according to latest figures from the National Health and Family Planning Commission.

(Xinhua News Agency May 3, 2013)