Photo Credit – FAO
Although its track record in infecting humans is limited to only one known case (see May 2014 Sichuan China: 1st Known Human Infection With H5N6 Avian Flu), the emergence of a highly pathogenic H5N6 virus on a poultry farm in China earlier this spring has raised concerns that we might have yet another avian flu threat to contend with.
Similarly, last January we saw a highly pathogenic H5N8 virus appear in South Korea, which resulted in the culling of more than 10 million birds, and significant economic losses. The virus also briefly appeared in Japan, but since its arrival was anticipated, it was quickly contained.
While the (multiple stains) of H5N8 in South Korea have yet to infect a human, we have seen evidence of their ability to seroconvert in canines (see Korea Found Dogs With H5N8 Antibodies). Both of these emerging avian viruses are related to the highly pathogenic H5N1 virus, which over the past 12 years has become endemic in a half dozen Asian and Middle Eastern countries.
These new subtypes come about from a process called antigenic shift, or reassortment.
For shift to happen, a host (human, swine, or avian) must be infected by two influenza different viruses at the same time. Shift occurs when one virus swap out chunks of their genetic code with gene segments from another virus.
With literally dozens of avian subtypes and clades circulating in avian, canine, equine, and swine populations there are ample opportunities for new hybrids to be generated. Most will be evolutionary failures, less fit than the viruses already in circulation, and will die out.
But every once in awhile a new virus emerges which has the possibility of being a contender.
After making a brief appearance last April in China, we hadn’t heard anything about HPAI H5N6 until earlier this week (see OIE: Two Outbreaks Of H5N6 In Vietnamese Poultry). Now the concern is over just how widespread this new virus might be, since the two detections were several hundred kilometers apart.
Location of Outbreaks – Source OIE
Overnight Vietnam’s MARD (Ministry of Agriculture & Rural Affairs) issued the following warning on this new virus.
(MARD - 08/14/2014) To proactively prevent influenza virus A / H5N6 influenza viruses and other poultry, minimize influenza virus infection and fatal to humans, affects community health, reduce economic losses to the livestock industry; Ministry of Agriculture and Rural Development proposed Chairman of the People's Committees of provinces and centrally run cities concerned, only the People's Committees at all levels and departments of local implementing measures measures to prevent bird flu in the spirit of power steering at the 200 / CD-TTg of the Prime Minister dated 02.14.2014 focus on avian flu and avian influenza viruses infect humans.
For more information please see the attached file here.
And from Hanoimoi.com.vn
Friday 08/15/2014 06:32
(HNM) - Afternoon 14-8, Deputy Minister of Health Nguyen Thanh Long has sent urgent dispatches signing Chairman provinces and cities across the country to strengthen the prevention and control of influenza A / H5N6.
Accordingly, at the announcement of the Department of Animal Health (MARD) through active surveillance has detected a number of cases positive for influenza A / H5N6 in chickens raised in Trang Dinh district, Lang Son and the ducks feed Ky Anh district, Ha Tinh province. This is the first time the influenza virus A / H5N6 were reported in Vietnam. Test results with gene sequencing of virus samples of influenza A / H5N6 detected in our country that there is a 99% similarity with the strain of influenza A / H5N6 deaths in the first in Sichuan Province, China Nations in January 4-2014. According to the World Organization for Animal Health, this is a highly virulent strain and no evidence of transmission from person to person, so the monitoring and supervision of the new strain changes need to be done to close apps timely response to outbreaks in poultry.
This expanding array of new avian influenza subtypes hasn’t been limited to just the H5s.
While up until last spring, if you talked about avian flu - most people would assume you meant the H5N1 `bird flu’ which re-emerged in Vietnam in 2003 and subsequently spread globally . But things have changed considerably over the past 18 months.
Since then we’ve seen two impressive waves of the H7N9 epidemic in China, Taiwan reported Infection With Avian H6N1 last year, and last winter no fewer than three human cases of H10N8 infection were reported in China.
To that you can add a handful of H7 infections in Italy, an occasional H9N2 infection in Asia, and continued sporadic infections with Swine variant viruses (H1N1v, H1N2v, H3N2v) in North America (see Keeping Our Eyes On The Prize Pig)..
Of course, none of this guarantees that one of these above mentioned emerging viruses will adapt well enough to humans to pose a global health threat.
We’ve watched H5N1 for more than a decade, and it hasn’t managed to increase its transmissibility despite splitting into more than 20 clades.
But it is a numbers game - the more novel flu viruses that are out there swapping gene segments and picking up host-adaptive amino acid substitutions - the better the odds are that one of these viruses will someday hit the jackpot.
And if the past 18 months are any indication, the roster of new influenza subtypes to keep track of will only likely continue to expand.