Sunday, January 30, 2011

What Goes Around, Comes Around



# 5271



With bird flu outbreaks among poultry and wild birds increasing across South Korea and Japan (North Korea and possibly China are unknown factors), other Asian countries that see migratory bird visitations over the winter are understandably on the alert.


Today, a news release form the National News Bureau of Thailand, Public Relations office that reflects their concern. 


Bird flu fear sparks warning across the country

BANGKOK, 30 January 2011 (NNT)-Public Health Minister Jurin Laksanawisut has instructed public health services across Thailand to warn people of a possible outbreak of bird flu in human, although there has been no report on any one contracting the disease so far.


Following an unidentified cause of death of 100 chickens in Sam-Chuk district, Suphan Buri province, local residents fear H5N1 or commonly known as bird flu was the reason. However, an autopsy on dead chickens are still underway. Mr. Jurin has taken a precautionary step and instructed health services to coordinate with officers from the Department of Livestock and the Department of Agriculture for help.


According to the Health Minister, it is important that people are aware of risks and know how to protect themselves against the flu. People have also been warned not to come in contact with dead poultry. Mr. Jurin said even though Thailand has been free of the flu since 2006 ,the Ministry of Public Health will continue to monitor the disease to safeguard the health of the Thai people


We’ll have to wait to hear if this turns out to be anything, but it gives you an idea of how seriously officials are taking these latest outbreaks.


Japan, Korea, and Thailand are part of the great East Asian - Australasian Flyway. All three countries are the winter home for many species of migrating birds, many of which spend their summers in Siberia, China, and Mongolia. 


There are, however - overlaps between these flyways - enabling pathogens to be carried from one to another.




In what may turn out to be a related story, yesterday in an EID dispatch (see EID Journal: H5N1 Branching Out) we saw a report out of Qinghai, China indicating that a new (for them) clade 2.3.2  of H5N1 bird flu was reported in wild birds near major migratory nesting grounds back in 2009 (admittedly, news travels slow out of China).


Clade 2.3.2 isn’t new, of course. 


It’s been circulating - primarily among poultry in Vietnam and parts of China - since the middle of the last decade, and started showing up in wild bird surveillance a couple of years later.


In March of 2009, the CDC’s EID Journal published the following report.


Characterization of Avian Influenza Viruses A (H5N1) from Wild Birds, Hong Kong, 2004–2008

Gavin J.D. Smith,1 Dhanasekaran Vijaykrishna,1 Trevor M. Ellis, Kitman C. Dyrting, Y.H. Connie Leung, Justin Bahl, Chun W. Wong, Huang Kai, Mary K.W. Chow, Lian Duan, Allen S.L. Chan, Li Juan Zhang, Honglin Chen, Geraldine S.M. Luk, J.S. Malik Peiris, and Yi Guan


Genetic and antigenic characterization of 47 HPAI (H5N1) viruses isolated from dead wild birds in Hong Kong showed that these isolates belonged to 2 antigenically distinct virus groups: clades 2.3.4 and 2.3.2.


Although research has shown that clade 2.3.4 viruses are established in poultry in Asia, the emergence of clade 2.3.2 viruses in nonpasserine birds from Hong Kong, Japan, and Russia raises the possibility that this virus lineage may have become established in wild birds.



Passerine birds encompass `perching birds’ & songbirds, while nonpasserine birds include ducks, swans, storks, ostriches, aquatic water fowl, quail, turkeys, and gulls . . . among many others.


In Late November of 2010, after 2 and 1/2 years without an outbreak, the H5N1 virus was detected at a poultry farm in Japan (see Japan: Bird Flu Investigation At Poultry Farm).  


Subsequently, the OIE WAHID follow up report # 1 identified the strain as being clade 2.3.2.  A hat tip to Ironorehopper for archiving the following information on his website:


Highly pathogenic avian influenza, Japan (WAHID Interface - OIE World Animal Health Information Database, Dec. 09 2010, edited

Epidemiological comments

  • It is considered that the virus was carried to the surroundings of the farm by migratory birds because the outbreak occurred in a season when migratory birds came flying from the north to Lake Nakaumi nearby the farm.

  • The virus might have invaded the affected henhouse through wild birds, wild animals or others.

  • The National Institute of Animal Health affirmed by comparison of gene sequence that the isolate is classified into clade 2.3.2 and a closely-related strain with the virus isolated from faeces of migratory wild ducks in Hokkaido in October 2010.

  • The homology between these viruses is 99.6%.


We’ll have to await further phylogenetic analysis from other farms in Japan, Korea, and elsewhere to know for certain .  .  .  but it certainly appears that the  2.3.2 clade has become well established in migratory birds.


While that in itself may not be a game changer, it is a reminder that the bird flu virus isn’t just a moving target.


It is actually a half dozen (or more) moving targets.  And that just counts the H5N1 clades.


With myriad influenza A viruses comingling, swapping genetic material, and continually trying out new genetic combinations in order to make a better, more `fit’ virus – it is imperative that we do what we can to improve global pathogenic surveillance and reporting.


Because experience has shown us, diseases that go around in one part of the world, have a nasty habit of eventually coming around to the rest of the planet.

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