The U.N. Food & Agriculture Organization Monday urged heightened readiness and surveillance against a possible major resurgence of H5N1 highly pathogenic avian influenza amid signs that a mutant strain of the deadly virus is spreading in Asia and beyond with unpredictable risks to human health.
FAO pointed to World Health Organization numbers showing that the H5N1 virus has infected 565 people since it first appeared in 2003, killing 331 of them. The latest death occurred earlier this month in Cambodia, which has registered eight fatal cases of human infection this year.
Since 2003, H5N1 has 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.
However, the virus remained endemic in six nations, although the number of outbreaks in domestic poultry and wild bird populations shrank steadily from an annual peak of 4,000 to just 302 in mid-2008. However, since then, outbreaks have risen progressively with almost 800 cases recorded in 2010-11.
At the same time, 2008 marked the beginning of renewed geographic expansion of the H5N1 virus both in poultry and wild birds.
The advance appears to be associated with migratory bird movements, according to FAO chief veterinary officer Juan Lubroth, who noted that migrations help the virus travel over long distances, so that H5N1 has in the past 24 months shown up in poultry or wild birds in countries that had been virus-free for several years.
Recently affected areas include Israel and the Palestinian Territories, Bulgaria, Romania, Nepal and Mongolia.
A further cause for concern, Lubroth said, is the appearance in China and Vietnam of a variant virus apparently able to sidestep the defenses provided by existing vaccines.
In Vietnam, which suspended its springtime poultry vaccination campaign this year, most of the northern and central parts of the country - where H5N1 is endemic - have been invaded by the new virus strain, known as H5N1-22.214.171.124, FAO said.
"The general departure from the progressive decline observed in 2004-08 could mean that there will be a flare-up of H5N1 this fall and winter, with people unexpectedly finding the virus in their backyard," Lubroth said.
The countries where H5N1 is still firmly entrenched - Bangladesh, China, Egypt, India, Indonesia and Vietnam - are likely to face the biggest problems but no country can consider itself safe, he said.Source: Feedstuffs