A variant of H5N1 virus that is apparently able to sidestep the effects of the existing vaccines has appeared in Vietnam and China, the United Nations' Food and Agriculture Organization (FAO) said on its website.
This together with the virus's renewed geographic expansion in both poultry and wild birds starting in 2008 are posing a risk of a major resurgence of the H5N1 Highly Pathogenic Avian Influenza, the organization said in the article dated Monday.
In fact, Vietnam already suspended its springtime poultry vaccination campaign this year due to the new virus strain, known as H5N1 184.108.40.206, which has invaded most of the country's northern and central regions, according to FAO.
Virus circulation in Vietnam poses a direct threat to Cambodia, Thailand and Malaysia as well as endangering the Korean peninsula and Japan further afield, it said, adding that wild bird migration can also spread the virus to other continents.
Meanwhile, over the past 24 months bird flu has showed up in poultry or wild birds in countries that had been virus-free for several years, FAO Chief Veterinary Officer Juan Lubroth said in the statement.
The geographic expansion appears to be associated with migratory bird movements, he added.
Recently affected areas are to be found in Israel and the Palestinian Territories, Bulgaria, Romania, Nepal and Mongolia, the organization said.
According to Lubroth, the endemic's decline observed in 2004-2008 could mean that there will be a flare-up of H5N1 this fall and winter.
"Preparedness and surveillance remain essential," Lubroth underlined. "This is no time for complacency. No one can let their guard down with H5N1."
Since it first appeared in 2003, the virus has infected 565 across the world, killing 331 of them, the article quoted the World Health Organization's figures as saying. The latest death was recorded earlier this month in Cambodia.
H5N1 has also killed or forced the culling of more than 400 million domestic poultry and caused an estimated $20 billion of economic damage across the globe before it was eliminated from most of the 63 countries infected at its peak in 2006, FAO said.
Currently it the virus remained endemic in six nations Bangladesh, China, Egypt, India, Indonesia and Vietnam.