Different strains of bird flu have been spreading across Europe and Asia since late last year, leading to large-scale slaughtering of poultry in some countries and human deaths in China.

Nearly 40 countries have reported outbreaks of highly pathogenic avian influenza in poultry or wild birds since November, according to the WHO.

"The rapidly expanding geographical distribution of these outbreaks and the number of virus strains currently co-circulating have put WHO on high alert," the UN agency's director-general, Dr Margaret Chan, said at the start of its executive board meeting in Geneva yesterday.

The new H5N6 strain causing severe outbreaks in Asia was created by gene-swopping among four different viruses, she added.

The world was better prepared for the next influenza pandemic, following the H1N1 pandemic that circled the world from 2009 to 2010, "but not at all well enough", Dr Chan warned.

In China, there had been a "sudden and steep increase" in human cases of H7N9 since last month and the WHO had not been able to rule out limited human-to-human spread in two clusters of human cases, she said.

Under the International Health Regulations, a binding legal instrument, the WHO's 194 member states are required to detect and report human cases promptly, Dr Chan noted, adding: "We cannot afford to miss the early signals."

China's delegation, led by Ms Zhang Yang of the National Health and Family Planning Commission, told the meeting that the country would fulfil its obligations on communicating and responding to any outbreaks.

"Currently H7N9 overall statistics remain the same," Ms Zhang said. "China will continue to strengthen its cooperation and exchange with WHO in this regard."

REUTERS