AsianScientist (Aug. 29, 2011) – The Food and Agriculture Organization of the United Nations (FAO) today predicted a possible major resurgence of the H5N1 Highly Pathogenic Avian Influenza, amid signs that a mutant strain of the virus called H5N1-2.3.2.1 is spreading in Asia and beyond.
The H5N1 virus has infected 565 people since it first appeared in 2003, killing 331 of them, according to World Health Organization (WHO) figures.
The latest death occurred earlier this month in Cambodia, which has registered eight cases of human infection this year – all of them fatal.
Since 2003, the virus has killed or forced the culling of more than 400 million domestic poultry and caused an estimated US$20 billion of economic damage across the globe, before it was eliminated from most of the 63 countries infected at its peak in 2006.
Although the virus remained endemic in six nations, the number of outbreaks in domestic poultry and wild bird populations shrank steadily from an annual peak of 4000 to just 302 in mid 2008.
In the past year however, outbreaks have risen progressively since, with almost 800 cases recorded in 2010-2011.
“The general departure from the progressive decline observed in 2004-2008 could mean that there will be a flareup of H5N1 this fall and winter, with people unexpectedly finding the virus in their backyard,” said FAO Chief Veterinary Officer Juan Lubroth.
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 is safe, Lubroth said.
At the same time, 2008 marked the beginning of renewed geographic expansion of the H5N1 virus both in poultry and wild birds, with a PloS ONE study describing the transmission of the highly pathogenic H5N1 virus between domestic farms and wild birds in Tibet.
“Wild birds may introduce the virus, but people’s actions in poultry production and marketing spread it,” Lubroth noted.
New H5N1-2.3.2.1. viral strain in Vietnam
A further cause for concern, Lubroth said, is the appearance in China and Vietnam of a variant virus existing vaccines cannot protect against.
In Vietnam, which suspended its springtime poultry vaccination campaign this year, most of the northern and central parts of the country have been invaded by a new viral strain known as H5N1-2.3.2.1.
In response to this mutant avian flu strain, Vietnam’s veterinary services are reportedly considering a novel, targeted vaccination campaign this fall.
Viral circulation in Vietnam poses a direct threat to Cambodia, Thailand, and Malaysia as well as endangering the Korean peninsula and Japan further afield, cautioned the UN report.
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Source: Food and Agriculture Organization of the United Nations.
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