India: The H5N1 & Migratory Birds Debate

Credit U.S. Fish and Wildlife Service

 

# 6686

 

One of ongoing debates in the world of avian influenza is over exactly how much of a role migratory birds play in the spread of highly pathogenic H5N1.  

 

Bird enthusiasts tend to point to the poorly managed poultry trade as being the main source of the spread of bird flu while those in the poultry industry are often quick to blame migratory birds.

 

Over the years we’ve studies that either implicate migratory birds in the spread of the virus, or minimizes their role (see  India: The Role Of Migratory Birds In Spreading Bird Flu).

 

Personally, I see no reason why these positions should be mutually exclusive.  As far as I can tell, both are important factors in the spread of the virus.

 

But the debate goes on, often heatedly.

 

The recent outbreak of H5N1 in India (see  Bangalore: More Poultry Culled Due To H5N1) at a government poultry farm is very near Hesaragatta lake - a man-make reservoir and winter nesting ground for migratory birds that has fallen into disrepair in recent years from a lack of water. 

 

Reportedly, the number of birds that now visit every year is greatly reduced.

 

Nevertheless, several thousand birds continue to stop over at Hesaragatta lake each winter, and that has prompted local officials to suggest that migratory birds are to blame for the current outbreak.

 

A position that local ornithologists are taking serious umbrage over.

 

First a link to the article from DNA (Daily News & Analysis) that attempts to exonerate wild birds as carriers of the H5N1 virus, then I’ll return with some comments of my own.

 

Experts debunk migratory birds theory

Published: Thursday, Nov 1, 2012, 15:50 IST
By Aishhwariya Subramanian | Place: Bangalore | Agency: DNA

The hunt for the elusive cause of the avian influenza outbreak at Central Poultry Development Organisation & Training Institute (CPDOTI) on Tuesday saw officials of animal husbandry department blaming migratory birds for carrying the virus. But ornithologists have debunked the theory despite animal husbandry officials stating that the Hesaraghatta Lake close to CPDOTI facility which attracts migratory birds was the culprit for the outbreak.

(Continue . . . )

 

The arguments being made by the experts interviewed in this article are basically two pronged. 

 

• The first seems to be the old canard that `sick birds don’t fly’
• The second is the reduced number of migratory birds arriving at the reservoir in recent years.

 

While it’s true that wild birds that acquire the virus, sicken, and die are less likely to transfer the virus across long distances, the `sick birds don’t fly’  stance ignores the fact that in migratory waterfowl, the H5N1 is often an asymptomatic infection.

We’ve looked at asymptomatic waterfowl as reservoirs of the virus a number of times in the past, including:

Reservoir Ducks

Webster On China's `Silent' Bird Flu Infections

Mallard Ducks Found To Be Asymptomatic To Bird Flu Virus

We’ve also witnessed the geographic spread of new clades of the H5N1 virus in migratory waterfowl, and the apparent importation of H5N1 into Hong Kong, Japan, and South Korea by the arrival of migratory birds in the past.

 

EID Journal: H5N1 Branching Out

Study: The Role Of Migratory Birds In Spreading Bird Flu

Egrets, They’ve Had A Few . . .

Japan: Hooded Crane Positive For H5N1

Wild Birds Eyed As Likely Source Of Hong Kong Bird Flu Outbreak

FAO: On The Trail Of Avian Influenza

 

 

The second argument, that the number of migratory birds arriving each year at Hesaragatta lake has recently dropped may reduce the odds that birds brought the virus to Bangalore, but it certainly doesn’t eliminate the possibility.

 

The bottom line - it just takes one infected bird to arrive and introduce the virus to the environment.

 

None of which tells us how the H5N1 virus made it to a government poultry operation in Bangalore, but it does help put migratory birds as carriers of avian flu into better perspective.

 

Lest bird lovers cry `fowl’, the role of poultry producers in the spread of avian flu – including, but not limited to: poor biosecurity, overcrowded conditions, covering up reports of illnesses or deaths among birds, and smuggling – are well documented in this blog, and elsewhere.

 

While migratory birds appear to have a role in introducing avian flu viruses to new regions, poorly run poultry operations obviously help to amplify and spread these viruses further.

 

The fact that this debate is unresolved nearly a decade after the re-emergence of H5N1 in 2003 underscores the need for better research and surveillance, both in migratory birds and in poultry operations.

 

 

Until we can clearly understand the various mechanisms by which this virus is spread, the prospects of halting outbreaks in the future remain slim.

»» Read More

Hong Kong: Two H5 Positive Gulls Found

 

 

 

# 6049

 

Hong Kong is one of the few places in the world where public health authorities take notice of something as seemingly inconsequential as a single dead bird.

 

To understand why, you have to go back to 1997, when the H5N1 Bird Flu virus suddenly appeared in Hong Kong – infecting 18 residents and killing 6.

 

The source of the infection, it was discovered, was their domesticated poultry industry. It was only the complete eradication of all poultry in the territory that managed to halt what many feared could have been a disaster.

 

Since then, Hong Kong has kept a particularly watchful eye.

 

Not only on people (they test flu strains more thoroughly than perhaps anyplace in the world), but also on birds, both wild and farmed. 

 

In December of 2008, Hong Kong saw their first outbreak of H5N1 in domesticated poultry in nearly 6 years.   This once again set off alarm bells, and sparked intense debate on how the virus managed to get past their biosecurity measures.

 

In January of 2009 it was announced that the H5N1 outbreak was `likely’ caused by infected migratory birds.  See Wild Birds Eyed As Likely Source Of Hong Kong Bird Flu Outbreak.

 

In spite of few reports of infected wild birds in mainland China (due, no doubt to less than robust surveillance and reporting), most years we hear of at least a dozen H5 positive migratory birds making it into Hong Kong.

 

With each announcement, calls go out to increase biosecurity measures at local poultry farms.

 

The recent high-profile death of a 39 year-old bus driver from the H5N1 virus in the neighboring city of Shenzhen (see China Seeks To Reassure On Bird Flu) undoubtedly serves to heighten their vigilance.

 

 

This from the Centre For Health Protection.

 

 

 

Black-headed gulls test positive for H5 virus

Two dead Black-headed gulls found in Tuen Mun and Lantau have tested positive for the H5 avian influenza virus in preliminary testing, a spokesman for the Agriculture, Fisheries and Conservation Department (AFCD) said today (January 3), adding that further confirmatory tests are being conducted.

 

The first gull was collected at EcoPark, 133 Lung Mun Road, Tuen Mun, on December 30, 2011 while the second one was found at a drain near Sha Lo Wan Soccer Pitch, Lantau, on January 1.

 

The Black-headed gull is a common winter visitor.

 

The spokesman said there were no poultry farms within three kilometres of where the dead birds were found.

 

The AFCD has phoned poultry farmers to remind them to strengthen precautionary and biosecurity measures against avian influenza. Letters have been issued to farmers, pet bird shop owners and licence holders of pet poultry and racing pigeons, reminding them that proper precautions must be taken.

 

The spokesman said the department would conduct frequent inspections of poultry farms and the wholesale market to ensure that proper precautions against avian influenza have been implemented. The department will continue its wild bird monitoring and surveillance.

 

"People should avoid personal contact with wild birds and live poultry and their droppings. They should clean their hands thoroughly after coming into contact with them. The public can call 1823 for follow-up if they come across suspicious sick or dead birds, including the carcasses of wild birds and poultry," the spokesman said.

(Continue . . . )

 

Ends/Tuesday, January 3, 2012
Issued at HKT 18:13

»» Read More

Hong Kong: Tracing Contacts Of H5 Positive Bird

 

 

Note: This story is updated in  Hong Kong Woman Tests Negative For H5N1

 

# 6010

 

Hong Kong – which was the site of the first known cluster of human H5N1 cases nearly 15 years ago – is one of the few places in the world where public health authorities take notice of something as seemingly inconsequential as a single sick (or dead) bird. 

 

Located adjacent to mainland China - which has long history of H5N1 outbreaks in poultry and in wild birds - Hong Kong authorities remain vigilant for any signs of encroachment by the virus.

 

Photo Credit- Wikipedia

 

While surveillance and reporting from the mainland are often lacking, the detection of H5N1 in dead chickens floating down the Pearl River (see  The Winter Of Our Disbelief), and in migratory waterfowl (see Hong Kong Discovers Another Infected Heron) over the years, point to the mainland as an ongoing source of the virus.

 

The danger that humans would contract the virus from coming in contact with the occasional infected wild bird is considered fairly remote, but not zero.

Which explains the furor today over a sick (later determined to be H5 positive) bird that was discovered recently at a secondary school in Yuen Long.

 

Apparently at least one person (48, F) who had contact with the bird is now showing signs of influenza-like-illness, and has been placed in isolation at Princess Margaret Hospital (PMH) for further testing.

 

It should be noted that this is cold & flu season, and that there are other common viral illnesses that could produce similar symptoms.

 

We’ll have to wait for confirmation to know if this woman has been infected with the H5N1 virus.

 

Hong Kong’s Centre for Health Protection  (CHP) is leading the investigation, and has published this press release:

 

CHP is tracing the contacts of the H5 dead bird

Thursday, December 15, 2011
Issued at HKT 19:52

The Centre for Health Protection (CHP)  of the Department of Health is liaising with the Agriculture, Fisheries and Conservation Department (AFCD) in tracing persons who had potential contact with the Black-headed Gull found at Chiu Lut Sau Memorial Secondary School, Yuen Long, which was tested positive in the preliminary test for H5 avian influenza virus.

 

So far, one of the contacts was symptomatic and she was arranged to admit to Princess Margaret Hospital (PMH) for further testing and isolation. The other contacts have been put under medical surveillance.

 

Preliminary investigation revealed that the 48-year-old woman, who worked as clerical staff in the school, had picked up the sick bird with bare hand and without face mask on December 13 and placed it in a box in the school office before it was collected by the AFCD. She developed fever, sore throat and diarrhea the next day and consulted a private doctor today (December 15).

 

"In view of the latest development, the patient has been sent to PMH for isolation and treatment. Tests for H5 are being conducted and results will be available tomorrow morning," a CHP spokesman said.

 

According to the information in hand, the patient enjoyed good past health. She did not have recent travel history.

 

The spokesman said, "The CHP has identified six home contacts of the patient and all of them are currently asymptomatic. Of them, the 11-year-old son of the patient developed fever and cough on December 13 and has now recovered.  As a precautionary measure, he has been arranged to PMH for isolation and laboratory testing. Contact tracing continues."

 

"The school has been advised to suspend class for a day tomorrow (December 16) for thorough cleansing and disinfection. The CHP will assess the need for further class suspension subject to development."

Ends/Thursday, December 15, 2011

 

 

The news.gov.hk website also has the following news story regarding this case.

 

Woman ill after touching bird with virus

December 15, 2011

People are urged to avoid contact with birds after a woman fell ill after touching a black-headed gull which later tested positive for the H5 avian influenza virus.

 

Centre for Health Protection Controller Dr Thomas Tsang told reporters today the 48-year-old woman developed flu symptoms yesterday, a day after she picked up the sick bird with her bare hands.

 

He said the woman and her 11-year-old son have been sent to Princess Margaret Hospital for tests and the results are expected tomorrow morning. Other family members have no symptoms.

 

The Agriculture, Fisheries & Conservation Department collected the sick bird on December 13 from Chiu Lut Sau Memorial Secondary School in Yuen Long, where the woman works. The bird died the next day. More tests are underway.

 

Dr Tsang has advised the school to suspend classes tomorrow for thorough disinfection.

 

The Agriculture, Fisheries & Conservation Department has inspected four chicken farms nearby and found no abnormal deaths. It is reminding poultry farmers to strengthen precautionary measures.

 

People should call 1823 if they come across suspicious sick or dead birds.

 

All relevant government departments will continue to remain vigilant and enforce preventive measures against bird flu.

 

 

I’ll report back any news we get on the laboratory tests and investigation.

»» Read More

Satellite Images Show Where The Wild Goose Goes

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#5639



Wild water birds (ie. duck, geese, swans, terns, gulls) are the natural reservoir for avian influenzas (including, but not limited to H5N1), and unlike many terrestrial species, can often carry the virus with little or no ill effect.

Avian influenza is primarily a gastrointestinal infection among birds, and it can be spread through virus laced feces deposited in shared ponds and lakes.

The role of wild birds in the spread of bird flu is not without its controversy. Over the years we’ve a number of studies that either implicate migratory birds in the spread of the virus, or minimizes their role.

In September 2010 (see Another Migratory Bird Study) a paper appeared in the British Ecological Society's Journal of Applied Ecology, that claimed that the global spread of the H5N1 virus through migratory birds was possible . . . but unlikely.

In a blog from 2009, called  India: The Role Of Migratory Birds In Spreading Bird Flu I wrote about an article entitled  Scientists rule out spreading of bird flu by migrant birds in India  from Xinhua News.

And in January of 2008, Reuters carried a report called: Don't blame wild birds for H5N1 spread: expert

Despite these dissenting opinions, there have been plenty of other reports that strongly associate migratory birds with the spread of the virus.

A few include:

Korea: Migratory Birds Behind Spread Of H5N1

EID Journal: H5N1 Branching Out

Japan: Hooded Crane Positive For H5N1

FAO: On The Trail Of Avian Influenza

Despite overlapping migratory flight paths, avian strains common in Eurasian birds have yet to appear in North America.   Monitoring continues in every year, however.


Which brings us to a fascinating bit of research presented as a doctoral thesis by Ms Yali Si, a graduate student at the University of Twente in the Netherlands.


Using satellite imagery and field tests, Yali Si has worked to determine which grasslands are more likely to attract water birds to feed. She found that the age and quality of the grass affects selection by migratory birds.


Using this information, she has produced risk maps of Europe showing the areas most likely to visited by wild water birds, and therefore most vulnerable to the spread of avian flu.


While demonstrating the feasibility of this method, Yali Si states that additional study will be needed to refine the system and the resultant maps.


For more on this, we have a press release from the University of Twente, and a link to the thesis. 

First the press release:

Satellite images to combat avian flu

The entire 139 page PDF of her thesis is available at http://www.itc.nl/library/papers_2011/phd/yalisi.pdf


As the author points out, global environmental change (including climate and land use) has the potential to shift migratory and nesting behavior of wild water birds.


Through the use of GIS (geographic information systems), remote sensing (primarily satellite data), and new spatial techniques scientists will be better able to predict where the avian influenza threat is likely to be the highest.


Which ought to give researchers a better idea where to test for the arrival of new avian viruses, and could serve as a warning to poultry producers of when and where to beef up their biosecurity.

»» Read More

Study: The Role Of Migratory Birds In Spreading Bird Flu

 

 

# 5442

 

 

One of the more contentious debates in the world of avian influenza is over exactly what role migratory birds play in the spread of highly pathogenic H5N1.  

 

Bird enthusiasts and naturalists tend to point to the poorly regulated and controlled poultry trade as being the main source of the spread of the bird flu virus, while those in the poultry industry tend to blame migratory birds.

 

Over the years we’ve seen study after study that either implicates migratory birds in the spread of the virus, or minimizes their role.

 

 

Last September (see Another Migratory Bird Study) a paper appeared in the British Ecological Society's Journal of Applied Ecology, that claimed that the global spread of the H5N1 virus through migratory birds was possible . . . but unlikely.

 

In a blog from 2009, called  India: The Role Of Migratory Birds In Spreading Bird Flu  I wrote about an article entitled  Scientists rule out spreading of bird flu by migrant birds in India  from Xinhua News.

 

And in January of 2008, Reuters carried a report called:

 

Don't blame wild birds for H5N1 spread: expert

BANGKOK (Reuters) - There is no solid evidence that wild birds are to blame for the apparent spread of the H5N1 virus from Asia to parts of Europe, Africa and the Middle East, an animal disease expert said on Wednesday.

 

There was also no proof that wild birds were a reservoir for the H5N1 virus, Scott Newman, international wildlife coordinator for avian influenza at the U.N.'s Food and Agriculture Organization, said at a bird flu conference in Bangkok.

(Continue . . . )

 

 

Despite these statements to the contrary, there have been plenty of other reports that strongly associate migratory birds with the spread of the virus.

A few include:

 

Korea: Migratory Birds Behind Spread Of H5N1

EID Journal: H5N1 Branching Out

Japan: Hooded Crane Positive For H5N1

Not One Of The Usual Suspects

FAO: On The Trail Of Avian Influenza

 

 

Since I don’t have a bird in this fight, I readily concede that both are probably significant contributing factors in the spread of the virus.

 

I see no reason why they should be mutually exclusive.

 

Which brings us to a study that was recently published in PLoS One  called:

 

 

Wild Bird Migration across the Qinghai-Tibetan Plateau: A Transmission Route for Highly Pathogenic H5N1

Diann J. Prosser, Peng Cui, John Y. Takekawa, Mingjie Tang, Yuansheng Hou, Bridget M. Collins, Baoping Yan, Nichola J. Hill, Tianxian Li, Yongdong Li, Fumin Lei, Shan Guo, Zhi Xing, Yubang He, Yuanchun Zhou, David C. Douglas, William M. Perry, Scott H. Newman

Background

Qinghai Lake in central China has been at the center of debate on whether wild birds play a role in circulation of highly pathogenic avian influenza virus H5N1. In 2005, an unprecedented epizootic at Qinghai Lake killed more than 6000 migratory birds including over 3000 bar-headed geese (Anser indicus). H5N1 subsequently spread to Europe and Africa, and in following years has re-emerged in wild birds along the Central Asia flyway several times.

Methodology/Principal Findings

To better understand the potential involvement of wild birds in the spread of H5N1, we studied the movements of bar-headed geese marked with GPS satellite transmitters at Qinghai Lake in relation to virus outbreaks and disease risk factors.

 

We discovered a previously undocumented migratory pathway between Qinghai Lake and the Lhasa Valley of Tibet where 93% of the 29 marked geese overwintered. From 2003–2009, sixteen outbreaks in poultry or wild birds were confirmed on the Qinghai-Tibet Plateau, and the majority were located within the migratory pathway of the geese. Spatial and temporal concordance between goose movements and three potential H5N1 virus sources (poultry farms, a captive bar-headed goose facility, and H5N1 outbreak locations) indicated ample opportunities existed for virus spillover and infection of migratory geese on the wintering grounds.

 

Their potential as a vector of H5N1 was supported by rapid migration movements of some geese and genetic relatedness of H5N1 virus isolated from geese in Tibet and Qinghai Lake.

Conclusions/Significance

This is the first study to compare phylogenetics of the virus with spatial ecology of its host, and the combined results suggest that wild birds play a role in the spread of H5N1 in this region. However, the strength of the evidence would be improved with additional sequences from both poultry and wild birds on the Qinghai-Tibet Plateau where H5N1 has a clear stronghold.

(Continue . . . )

 

 

 

The USGS has released a press statement on this study, (which was funded by USGS, FAO, National Science Foundation and the Chinese Academy of Sciences) that describes the project and the results.

 

New research suggests wild birds may play a role in the spread of bird flu

LAUREL, Md. -- Wild migratory birds may indeed play a role in the spread of bird flu, also known as highly pathogenic avian influenza H5N1.

 

A study by the U.S. Geological Survey, the United Nations Food and Agriculture Organization and the Chinese Academy of Sciences used satellites, outbreak data and genetics to uncover an unknown link in Tibet among wild birds, poultry and the movement of the often-deadly virus.

 

Researchers attached GPS satellite transmitters to 29 bar-headed geese – a wild species that migrates across most of Asia and that died in the thousands in the 2005 bird flu outbreak in Qinghai Lake, China. GPS data showed that wild geese tagged at Qinghai Lake spend their winters in a region outside of Lhasa, the capitol of Tibet, near farms where H5N1 outbreaks have occurred in domestic geese and chickens.

 

This is the first evidence of a mechanism for transmission between domestic farms and wild birds, said Diann Prosser, a USGS biologist at the USGS Patuxent Wildlife Research Center. "Our research suggests initial outbreaks in poultry in winter, followed by outbreaks in wild birds in spring and in the breeding season. The telemetry data also show that during winter, wild geese use agricultural fields and wetlands near captive bar-headed geese and chicken farms where outbreaks have occurred."

(Continue . . . )

 

 

Like most scientific studies, this one increments our knowledge, rather than completing it.

 

While falling a bit short of finding a smoking gun, it documents a plausible mechanism for the H5N1 virus to be spread from domesticated poultry to wild birds during the winter, and from there relayed primarily by asymptomatic birds along the migratory pathways. 

The authors conclude by stating:

Our study identifies QHL and Lhasa as important linkages between wild and domestic transmission of H5N1 and provides new supporting information regarding the role of wild birds in long distance spread of this virus.

 

Further investigation of wild birds and H5N1 transmission within the Central Asian Flyway will increase our understanding of how wild birds may contribute to virus circulation and the unique pattern of outbreaks in this remote region.

»» Read More

Korea: Migratory Birds Behind Spread Of H5N1

 

 

 

# 5294

 

 

While their conclusions are hardly a surprise given the number of infected migratory birds detected this year, from Yonhap News Agency this morning we get official statements on how the worst outbreak of H5N1 bird flu in Korea’s history has been spread.

 

Since November, both Korea and Japan have reported an unusually high number of H5N1 infected migratory birds, which authorities believe have reintroduced the virus into the nation’s commercial poultry.

 

The latest Korean numbers have 40+ farms with infections, and in excess of 5.4 million birds culled.   This exceeds the size and scope of their  April 2008 outbreak, with still a 2 or 3 more months of prime `bird flu season’ left to go.

 

All of this comes amid the worst outbreak of FMD (Foot and Mouth Disease) in South Korea’s history, requiring the destruction of more than 3 million pigs, cattle, sheep, and goats since November of 2010 (see South Korea Battles Bird Flu, FMD).

 

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

 

 

 

Today’s report quotes Joo Yi-seok, from the National Veterinary Research and Quarantine Service, as saying:

 

"Direct contact with infected wild birds and indirect contamination caused by people and vehicles stepping on bird droppings may have triggered 22 of the confirmed cases, with the rest involving the virus being spread inadvertently by contaminated bird feed and rice husks used in coops.”

 

Here’s the link to the Yonhap report.

 

2011/02/07 14:06 KST

Migratory birds trigger AI outbreak: gov't

 

 

After the initial spread of clade 2.2 of the H5N1 virus out of Qinghai Lake in 2006 to Europe and Africa and the rest of Asia, we saw a gradual reduction in the number of wild bird die offs around the world.

 

In 2007, it was even suggested by some OIE  researchers that the H5N1 virus might be on the wane in the wild (see Avian Flu Nearing End Of It's Cycle?).

 

But the H5N1 virus isn’t a single entity.  It is a collection of at least a half dozen different clades – each capable of independently mutating, changing, or adapting over time.  

 

And so - while the incidence of some clades may subside - others may rise.

 

Bird flu reports began to pick up again in 2008 and 2009, notably in Japan, Korea, Bangladesh, and India. Talk of the virus being in decline was quickly forgotten.

 

After another lull in reporting over 2009-2010, H5N1 is once again back in the news.

 

Whether the virus was really less active during that time, or our attention was simply diverted by the H1N1 pandemic, is hard to know.  

 

But what is obvious is that while there may be some cyclical pattern to outbreaks, the HPAI avian flu virus continues to be endemic in wild birds (particularly in China and Siberia), and is reasserting itself in countries that have managed to avoid it for nearly 3 years (see What Goes Around, Comes Around).

 

For now, the H5N1 virus is primarily a threat to wild birds, poultry and agricultural interests - and to a lesser extent - those who are in close contact with birds.

 

The virus remains poorly adapted to human physiology, and very difficult to catch.  Rarer still are cases where the virus spreads from one person to another.

 

But of course, the concern is that could change over time.

 

And so the world remains at Pre-pandemic Phase III on the H5N1 virus, and we continue to watch for any signs that the virus is adapting to humans.

»» Read More

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

(EXCERPT)

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.

»» Read More

Korea: Bird Flu Discovered In Teal Ducks

 

 

# 5183

 

 

Each winter, countless thousands of migratory birds make their way south from Mongolia, Siberia, and parts of China to over-winter on the Korean peninsula and in Japan.

 

In recent weeks we’ve been hearing of a small number of migratory birds being discovered in Japan, and to a lesser extent, in Korea (both are part of the East-Asian Flyway) with bird flu.  

 

 

 

Today, via Yonhap News, we learn of 20 teal ducks – found dead in Haenam - that have tested positive for a virulent (probably, but not stated to be H5N1 in this report) bird flu virus.  This is the third such discovery in a month, according to this report.

 

 

2010/12/28 17:04 KST

Dead teal ducks with bird flu strain found in S. Korea

 

SEOUL, Dec. 28 (Yonhap) -- South Korea's farm ministry said Tuesday that it has found 20 dead spectacled teal ducks, apparently affected by the virulent strain of bird flu, and have taken emergency decontamination measures.

The discovery of the dead birds in Haenam 430 kilometers south of Seoul is the third such finding this month and is raising concerns among local poultry farmers.

 

I’ve mapped the three main locations below, which are clustered near the end of the migration path for many of these birds.

 

 

Dutchy on FluTrackers has a thread with a couple of more translated news accounts, that identifies the strain as H5N1. 

 

You can follow that thread here.

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NWHC: Global Avian Influenza Update

 

 

 

# 5118

 

 

The National Wildlife Health Center (NWHC) division of the USGS maintains an avian influenza information page that they update at irregular intervals.

 

The latest update came on Friday, December 3rd, and it contains a roundup of recent outbreaks and a discussion of a report on the raising of bar-headed geese in China, and how that might be contributing to the spread of H5N1.

 

I’ve only excerpted (and reparagraphed for readability) the section on the raising of geese.

 

In addition you’ll find capsule reports on recent avian influenza outbreaks among poultry from Japan, Georgia, Vietnam, Canada (LPAI), and  Germany (LPAI).

 

Avian Influenza Information

---

News Update, December 3

H5N1 in Wild birds
China. Researchers believe that captive rearing of bar-headed geese in China provides a possible scenario for the emergence of the Qinghai Clade 2.2 bird flu virus and its occurrence in wild birds.

 

The first outbreak of H5N1 bird flu at Lake Qinghai occurred in 2005 and killed more than 6,000 birds, including more than 3,000 bar-headed geese. More outbreaks of bird flu all involving bar-headed geese occurred in the same area in 2006, 2007, 2009, and 2010.

 

It has been reported that there was little domestic poultry production in the areas surrounding these outbreaks. The authors of a letter to the Journal of Wildlife Disease (see citation below) discovered that raising bar-headed geese in captivity was practiced extensively in this region of China, raising the possibility of contact with wild birds.

 

Bar-headed geese have been raised in China since 2003 both for their meat and to supplement the declining wild population. The birds are often kept in close contact with domestic poultry and may have become infected with bird flu through them. At other times they graze outdoors with wild birds and could have transmitted the disease to wild flocks.

 

The authors found no direct evidence that captive rearing of bar-headed geese was involved in the outbreaks in the Qinghai lake area, but they believe the possibility deserves scientific study.

<SNIP>

H5N1 in the Scientific Literature

• Feare CJ et al. Captive Rearing and Release of Bar-headed Geese (Anser indicus) in China: A Possible HPAI H5N1 Infection Route to Wild Birds. J Wildl Dis. 2010;46(4):1340-2.
• Indriani R et al. Environmental Sampling for Avian Influenza Virus A (H5N1) in Live-Bird Markets, Indonesia. Emerg Infect Dis 16(12):1889.
• Potapova OV et al. Structural Changes in the Brain of Mice Infected with Influenza A/H5N1 Virus. Bull Exp Biol Med. 2009 Dec;148(6):892-5.

Other publications of interest

• Dos Reis M et al. Charting the host adaptation of influenza viruses. Mol Biol Evol. 2010 Nov 25. [Epub ahead of print]
• Hansbro PM et al. Surveillance and Analysis of Avian Influenza Viruses, Australia Emerg Infect Dis 16(12):1896.

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Another Migratory Bird Study

 

 

# 4865

 

 

In the wake of yesterday’s report that credited the Brown Headed Gull with spreading the H5N1 virus from China and Tibet down to Thailand, we get another study that minimizes the impact that migratory waterfowl may have in spreading the virus across long distances.

 

The study appears in the British Ecological Society's Journal of Applied Ecology, and claims that the global spread of the H5N1 virus through migratory birds is possible . . . but unlikely.

 

By studying 19 species of waterfowl, and making assumptions as to how long they may be able to carry the highly pathogenic H5N1 virus asymptomatically, these researchers say that there is a `limited window of opportunity’ for the virus to be spread over long distances by migratory waterfowl.

 

The press release may be read at:

Satellite data reveal why migrating birds have a small window to spread bird flu

 

 

The entire study is available for viewing at the link below:

 

Potential spread of highly pathogenic avian influenza H5N1 by wildfowl: dispersal ranges and rates determined from large-scale satellite telemetry

1. Nicolas Gaidet, Julien Cappelle, John Y. Takekawa, Diann J. Prosser, Samuel A. Iverson, David C. Douglas, William M. Perry, Taej Mundkur, Scott H. Newman

 

 

Although a lengthy study, the bottom line is summed up by points 3 & 4 of the author’s summary:

 

3. Our results indicate that individual migratory wildfowl have the potential to disperse HPAI H5N1 over extensive distances, being able to perform movements of up to 2900 km within timeframes compatible with the duration of asymptomatic infection.

4. However, the likelihood of such virus dispersal over long distances by individual wildfowl is low: we estimate that for an individual migratory bird there are, on average, only 5–15 days per year when infection could result in the dispersal of HPAI H5N1 virus over 500 km.

 

 

These results are based, of course, on a limited number of species, and calculations are predicated on assumptions based on the pathogenesis of HPAI in captive birds.

 

While likely not the last word on the subject, this study offers new insight into the potential of intercontinental spread of HPAI via migratory waterfowl.

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Where The Wild Duck Goes

 

# 4491

 

 

 

For a number of years there has been an ongoing dispute between various factions regarding how H5N1 (Bird flu) has managed to spread to more than 60 countries around the globe.

 

In what has sometimes been a contentious debate, bird enthusiasts and naturalists tend to point to the poorly regulated and controlled poultry trade as being the main source of infection, while those in the poultry industry tend to blame migratory birds.

 

Over the years we’ve seen conflicting reports and studies on the subject, and a good deal of rhetoric as well.  A few earlier blogs on this subject include:

 

FAO: On The Trail Of Avian Influenza

The Migratory Bird Connection

S.E. Asia: Crack Down On Poultry Smuggling

India: The Role Of Migratory Birds In Spreading Bird Flu

 

The rallying cry that `Sick birds don’t fly’ has been used to argue that migratory birds aren’t to blame for the spread of the virus, even though it has been shown that some species of birds (particularly ducks) can carry – and presumably spread – the virus asymptomatically.

 

Not being a lobbyist for either contingent, I find it perfectly reasonable to accept that the poultry trade and migratory birds could be responsible for the spread of the virus. 

 

I don’t see these as being mutually exclusive. 

 

While unlikely to answer the question to anyone’s satisfaction, the USGS website has details of a recent study that tracked pintail ducks in Japan during an H5N1 outbreak, and showed that they had both the means and opportunity to spread the virus.

 

They frequented wetlands where infected swans had been detected, and they subsequently migrated hundreds (sometimes thousands) of miles.

 

This is not exactly a smoking duck, of course.  

 

This research did not prove that these ducks actually spread the virus . . . only that they could have.  More research is obviously needed.

This from the USGS Newsroom.

 

 

Outbreak Study: Satellite Tracking Reveals How Wild Birds May Spread Avian Flu

Released: 4/12/2010 6:04:51 PM

For the first time, migratory birds marked with satellite transmitters were tracked during an outbreak of highly pathogenic H5N1 avian influenza virus (H5N1) in Asia, providing evidence that wild birds may be partly responsible for the spread of the virus to new areas.

 

In the study, scientists from the USGS Alaska Science Center and the University of Tokyo attached satellite transmitters to 92 northern pintail ducks several months before the H5N1 virus was discovered in dead and dying whooper swans at wetlands in Japan.

 

They found that 12 percent of marked pintails used the same wetlands as infected swans and that pintails were present at those sites on dates the virus was discovered in swans. During the first week after they become infected with H5N1, ducks such as pintails can shed the virus orally or in their feces, potentially contributing to the virus’ spread.

 

Researchers found that some of the marked pintails migrated 700 miles within four days of leaving the outbreak sites; marked pintails ultimately migrated more than 2,000 miles to nesting areas in eastern Russia.  The study’s discovery that northern pintails made long-distance migrations during the period when an infected duck would likely shed the virus offers insight on how H5N1 could be spread by wild birds across large areas.

 

The research, published in the journal Ibis, does not prove the marked pintails were actually infected with the H5N1 virus or that they definitively contributed to its spread.  However, it does demonstrate that pintails satisfied two requirements necessary for migratory birds to spread the virus: they used outbreak sites at times when the virus was present and some birds migrated long distances within a week of using the sites.

 

Jerry Hupp, Ph.D., a U. S. Geological Survey scientist and one of the lead authors of the study, noted that the H5N1 virus has been found in wild birds, including northern pintails, which show no visible signs of illness. Also, laboratory studies have shown that pintails and some other wild birds remain healthy when infected with H5N1.

 

“Consequently,” said Hupp, “infected wild birds that do not become ill, or birds that shed the virus before they become ill, may contribute to the spread of H5N1.”

 

The extent to which the virus has been spread via the wild bird trade, wild bird migration, and shipping of infected poultry or poultry products has been the focus of debate. “Studies of the movements of wild birds during H5N1 outbreaks can help scientists evaluate the overlap between migratory pathways and the occurrence of the virus,” Hupp said.

 

The region in eastern Russia that pintails migrated to is also an important migration and nesting area for many North American birds. Mingling of Asian and North American migrants in Russia can result in exchange of influenza virus genes. Previous USGS studies have demonstrated that northern pintails in Alaska often carry low pathogenic influenza virus genes that can be linked to Asian sources.

 

“Because northern pintails in Alaska exchange influenza viruses with Asian birds, movement of the H5N1 virus into eastern Russia would increase the risk for its transmission to North America via wild birds -- such as the northern pintail -- that migrate between continents,” said Hupp.

 

The study also noted that Japanese wetlands where the H5N1 virus was found are important migration habitat for other waterfowl, including as many as 11,000 Eurasian wigeon and 8,000 greater scaup, demonstrating the potential for large numbers of wild birds to pass through sites where the H5N1 virus is present if outbreaks occur during migration.

 

Although the highly pathogenic H5N1 virus has not been discovered in North America, it continues to plague the poultry industry throughout Eastern Europe, Asia and Africa and is a serious health threat to humans.

 

Satellite-tracking of northern pintail during outbreaks of the H5N1 virus in Japan: implications for virus spread was published in Ibis (February 2010, Volume 152) and was authored by Noriyuki Yamaguchi (University of Tokyo), Jerry Hupp (USGS), Hiroyoshi Higuchi (University of Tokyo), Paul Flint (USGS), and John Pearce (USGS).

 

For more information on avian influenza research, visit the USGS Alaska Science Center.

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The Migratory Bird Connection

 

 

# 4263

 

 

For several years there has been an ongoing dispute between various factions regarding how H5N1 manages to spread around the world. 

 

Bird enthusiasts and naturalists tend to point to the poorly regulated and controlled poultry trade as being the main source of infection, while those in the poultry industry tend to blame migratory birds.

 

Since I don’t have a bird in this fight, I readily concede the possibility that both are likely significant factors in the spread of the virus.  

 

Last April, just days before the world’s attention was diverted to a swine origin influenza, I wrote a blog about a study out of India that seemed to rule out migratory birds as a major spreader of the H5N1 virus.

 

In  India: The Role Of Migratory Birds In Spreading Bird Flu  I wrote about an article entitled  Scientists rule out spreading of bird flu by migrant birds in India  from Xinhua News.

 

At the time, I wrote:

 

It seems that every few months we get a new report that either implicates – or exonerates – migratory birds as a vector for the H5N1 virus.

 

Today, we get another study that claims to rule out migratory birds as spreaders of the H5N1 virus  in India.

 

Perhaps it’s so.

 

At least in the region of the world they investigated.

 

But there have been studies in other parts of the world that strongly suggest otherwise – that migratory birds do play a role in the spread of avian viruses.   

 

Just a few months before that study, we had this from Hong Kong:

 

Wild birds likely cause of avian flu outbreak

Nickkita Lau
Tuesday, January 06, 2009

A recent bird flu outbreak was likely caused by droppings from migrating wild birds rather than from smuggled ones, experts believe.

 

A government-appointed committee has completed its initial investigation into the deaths of 200 chickens in a Yuen Long farm early last month, which led to a cull of 100,000 birds and a 21-day ban on the sale of fresh fowl. The report will be submitted to the Food and Health Bureau this week.

 

According to a source, the report studied several possible factors behind the contamination but concluded there was no evidence linking it to smuggling activities. It was more likely caused by contaminated feces dropped by migrating birds inside the farm or nearby area, the report said.

 

 

But if you go back to January of 2008, we get this:

 

Don't blame wild birds for H5N1 spread – expert

 

Wed Jan 23, 2008 7:22am EST

BANGKOK, Jan 23 (Reuters) - There is no solid evidence that wild birds are to blame for the apparent spread of the H5N1 virus from Asia to parts of Europe, Africa and the Middle East, an animal disease expert said on Wednesday.

 

There was also no proof that wild birds were a reservoir for the H5N1 virus, Scott Newman, international wildlife coordinator for avian influenza at the U.N.'s Food and Agriculture Organisation, said at a bird flu conference in Bangkok.

 

After H5N1 was found in 2005 in a huge lake in central China where it killed over 10,000 wild birds, it turned up in parts of Europe, Africa and the Middle East, leading some experts to believe migratory birds may be to blame.

 

(Continue . . . .)

 

And so it goes, back and forth.

Today, a fresh report out of China that . . . .you guessed it . . . links migratory birds to outbreaks of H5N1.

 

While this may not be the last word on the subject . . . it most definitely is the latest.

 

 

Scientists discover avian influenza outbreak closely related to bird migration

www.chinaview.cn  2010-01-16 23:19:41

by Xinhua writer Yan Hao

KUNMING, Jan. 16 (Xinhua) -- A research jointly conducted by Chinese and Asian scientists has discovered that highly pathogenic avian influenza (H5N1) outbreak was closely related to bird migration.

 

The discovery was revealed at the fifth regional meeting of the Asian Partnership on Emerging Infectious Diseases Research (APEIR),which concluded on Saturday in Kunming, capital of southwest Yunnan Province.

 

Lei Fumin, researcher of Institute of Zoology with Chinese Academy of Sciences, told Xinhua that the research team had studied avian influenza outbreaks along the bird migration routes in the Qinghai-Tibet Plateau.

 

The research team consisted of Vietnamese, Cambodian, Thai, Indonesian and Chinese scientists.

 

Studies showed that avian influenza outbreaks in the Qinghai-Tibet Plateau were frequently coincided with bird migration both in time and location.

 

Studies on migratory birds of different species in different regions which could carry the influenza's virus showed that lakes and wetlands along the migration paths were key zones for the influenza viruses, Lei said.

 

The studies proved that the role of wild birds in the transmission of avian influenza should be paid great attention to, said Dr. Witthawat Wiriyarat from Thailand, who joined the research team.

 

(Continue . . .)

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