Photo Credit – FAO
# 6536
Overnight, the Vietnamese media has been carrying reports of a supposed recent change in the H5N1 virus, but before we get to that, a little background.
Just over a year ago (see FAO Warns On Bird Flu) concerns were raised in southeast Asia over the spread of a new clade of the H5N1 virus (2.3.2.1) that effectively evaded the poultry vaccine currently in use.
This 2.3.2.1 clade wasn’t really new, having been detected in China for several years. But in 2010-2011 it had begun to spread widely.
It was characterized last September (see WHO Report : Antigenic & Genetic Characteristics of H5N1 & H9N2 Viruses) as having appeared in wild birds and poultry in Bangladesh, China, Hong Kong SAR, India, Japan, the Republic of Korea, Myanmar, and Vietnam.
While the press briefly had a field day over this new strain the CDC , the OIE, and the World Health Organization quickly reminded us that while the bird flu threat remains, there was no evidence at the time to suggest that this new strain is any more transmissible to – and among – humans than the earlier strains.
The World Health Organization’s report from October of 2011, Updated unified nomenclature system for the highly pathogenic H5N1 avian influenza viruses, identifies and updates the known clades of the H5N1 virus that have emerged since the detection of the A/goose/Guangdong/1996 H5N1 virus strain back in the mid 1990s.
As you can see, the virus has evolved from one strain into a complex family of similar, but genetically distinct clades of H5N1. Some less successful clades have died out along the way, but many co-circulate around the globe.
All of which means we are not watching just one H5N1 virus strain, we are watching at least 20 genetically separate clades of the virus, with many minor variants of each clade thrown in the mix.
Or to put it another way, H5N1 – like all flu strains – is a constantly moving target, continually evolving, looking for an evolutionary advantage.
All of which serves as prelude to this morning’s report:
Overnight the Vietnamese media has carried numerous stories indicating some sort of change has been detected clade 2.3.2.1 of the H5N1 virus. My thanks go to Treyfish and Shiloh of FluTrackers for finding, and posting a number of these (English language & translated) reports in this thread.
Rather than deal with a kludgy machine translation, we’ll go with the Voice of Vietnam’s (VOV) English Language story.
Updated : 5:25 PM, 05/09/2012
New highly toxic avian flu virus spreads to Vietnam
A new strain of avian flu virus that was found in China two months ago has appeared in Vietnam, health experts have confirmed.
The new strain, 2.3.2.1 C, which has been detected through epidemic investigations, is highly toxic and therefore extremely deadly, Diep Kinh Tan, Deputy Minister of Agriculture and Rural Development, said at a meeting on September 4 to review the epidemic situation.
The 2.3.2.1 C strain has recently spread to Vietnam and is now present in affected areas in seven provinces and cities, namely Haiphong, Ha Tinh, Ninh Binh, Nam Dinh, Bac Kan, Thanh Hoa and Quang Ngai, said Hoang Van Nam, head of the Department of Animal Health (DoAH).
As the new strain is different from the A/H5N1 virus, the ministry is to conduct experiments and tests to confirm if the vaccines that are being used to combat A/H5N1 are also effective against the new strain.
If the existing medication is ineffective, studies on new vaccines against the new strain should be conducted soon, Tan said, adding that he has asked the DoAH to isolate the virus for this purpose.
Media reports such as this one are always a little dicey, since they contain very little in the way of hard scientific evidence. Hopefully we’ll get a clarification from the FAO, or an official statement from the Vietnamese government at some point.
What is apparent from this, and other reporting out of Vietnam, is that the H5N1 situation there continues to be fluid, and that concerns over the continual evolution and spread of the virus run high.
Although we continue to see isolated human infections around the world, and the virus continues to evolve (see H5N1: An Increasingly Complex Family Tree), for now H5N1 is primarily a threat to poultry.
The concern, of course, is that over time that could change.
And so the world remains at Pre-pandemic Phase III on the H5N1 virus, and we continue to watch for signs that the virus is adapting better to humans.
