The United Nations Monday urged greater preparedness and surveillance against a possible resurgence of bird flu, warning that the new mutant virus, H5N1 -, might affect Asia the most.

This new virus can apparently circumvent the defense of existing vaccines and create unpredictable human health hazards, the Food and Agriculture Organization said.

According to FAO, the virulent disease was under control after 2006, but in 2010 and 2011 almost 800 cases of bird flu from Israel, the Palestinian territories, Bulgaria, Romania, Nepal and Mongolia have been reported. In the last 24 months, the bird flu virus affected countries which had been virus-free for several years. The latest death, which occurred in Cambodia, is registered as the eighth fatal case in that country this year.

Bird flu first appeared in 2003, says the World Health Organization, and since then it has infected 565 people, killing 331 of them. According to the agency, H5N1 reached its peak in 2006, affecting 63 countries where more than 400 million domestic poultry were culled and economic damage of $20 billion had been caused.

Although the number of wild bird cases decreased since then from its peak of 4,000 to 302 in 2008, the H5N1 virus steadily renewed and expanded its geographical territory.

Migratory Birds Responsible for Bird Flu?

Migratory birds are responsible for the outbreaks of the H5N1 virus, believe experts. Their movements carry the mutant virus over long distances affecting poultry and wild birds of virus-free countries. Wild birds may introduce the virus, but peoples' actions in poultry production and marketing spread it, said FAO Chief Veterinary Officer Juan Lubroth.

Countries on High Alert

Vietnam’s veterinary services are on high alert and a targeted vaccination campaign will be organized this fall. Vietnam’s exposure to bird flu infection poses a direct threat to Cambodia, Thailand, Korea and Malaysia.

High alerts also have been issued for India, Indonesia, China, Japan and Malaysia. But as Lubroth underlines, no country should consider itself safe and should adopt heightened readiness and surveillance in order to protect itself from a possible epidemic.