Seroprevalence Study: Avian Flu In Chinese Pigs

 

Since pigs can be infected by more than one flu virus at the same time, the potential exists for two viruses to swap genetic material (reassort), resulting in a new hybrid strain.

 

# 6796

 

Although we tend to think of H5N1 whenever someone mentions `avian flu’, in truth there are many different avian influenza viruses.  If you go back far enough, all influenza A strains – even those thought of today as primarily adapted to humans, equines, or swine – appear to have an avian origin.

 

Influenza A viruses have 8 gene segments (PB2, PB1, PA, HA, NP, NA, M1, M2, NS1, NS2) and are broadly categorized by their HA (hemagglutinin) and NA (neuraminidase) genes.

 

With the recent discovery of H17N10 (see A New Flu Comes Up To Bat), scientists have now identified 17 different serotypes of Hemagglutinin (HA) and 10 serotypes of Neuraminidase (NA), which make many different combinations of HA and NA proteins possible.

Thus far, only about 100 of these combinations have been isolated in nature.

 

But the flu universe is far more diverse than that might lead to you believe, as influenza’s 8 gene segments are largely interchangeable parts. If you were to take two different influenza A viruses (say H3N2 and H5N1) and reshuffle them using reverse genetics, you can come up with 254 possible reassortments.

 

And within each of these HA/NA combinations you can have multiple clades (genetically distinct families), and within each clade, many minor variants – all of which makes for tremendous variety in these viruses.

 

Many of the the H1, H2, and H3 viruses have adapted to human physiology, but we occasionally see infection by other `novel’ strains. Most worrisome, due to its high fatality rate, is H5N1.  But we occasionally see (usually mild) infections by other avian strains.

 

MMWR: Mild H7N3 Infections In Two Poultry Workers - Jalisco, Mexico)

EID Journal: Human Infection With H10N7 Avian Influenza

PLoS One: Seroprevalence Of H9N2 In Poultry Workers – Pune, India

 

Last year scores of dead seals were discovered along the shoreline of New England, predominantly from the North Shore of Massachusetts to the southern coast of Maine.  Investigations showed (see mBio: A Mammalian Adapted H3N8 In Seals) their deaths to be due to a variant of the H3N8 avian flu strain, versions of which are known to also infect horses and dogs.

 

With the propensity of these avian strains to evolve and adapt, scientists are understandably very interested in any avian flu virus that appears to be moving towards `humanization’.

 

While it is possible for a flu virus to jump directly from birds to humans, often it requires an intermediate host to aid in its development. The graphic below illustrates that swine – which are generally susceptible to human and avian flu viruses - are considered excellent mixing vessels’ for influenza viruses.

 

 

The H1N1 `swine flu’ virus of 2009 kicked around in pigs for up to a decade before it adapted well enough to human physiology to spark a human pandemic. Over the past few years we’ve watched attempts by three other swine `variant’ viruses (H1N1v, H1N2v, H3N2v) to jump to mankind. 

 

Which makes the active surveillance of swine a potentially important tool for the early detection of emerging influenza viruses.

 

Unfortunately, while there are some surveillance systems in place, only a tiny fraction of the world’s swine population is actively monitored  (see Helen Branswell’s SciAm Article from late 2010 called Flu Factories).

 

All of which serves as prelude to a new study, recently published in the Journal of Clinical Microbiology, that found low levels of H3, H4, and H6 subtypes of avian influenza in Chinese pigs. Somewhat reassuringly, evidence of infection with the H5N1 virus was not found.

 

These H3, H4, and H6 avian viruses were not seen in a similar study done in 2001, suggesting their arrival into the swine population may be a recent development.

 

 

Seroepidemiological Evidence of Avian Influenza A Virus Transmission to Pigs in Southern China

Shuo Su, Wenbao Qi, Jidang Chen, Wanjun Zhu, Zhen Huang, Jiexiong Xie, and Guihong Zhang

J. Clin. Microbiol. published ahead of print 21 November 2012 doi:10.1128/JCM.02625-12

ABSTRACT

Recently, three novel avian-origin swine influenza viruses (SIVs) were first isolated from pigs in Guangdong Province, southern China, yet little is known about the seroprevalence of avian influenza among pigs in southern China. Here, we report for the first time the seroprevalence of avian H3, H4, and H6 influenza viruses in swine populations and the lack of seroepidemiological evidence of avian H5 influenza transmission to pigs in China.

 

A copy of the study can be downloaded here.

 

The American Society for Microbiology has published a press release with more information, excerpts of which you’ll find below:

 

 

 

Pigs in southern China infected with avian flu

WASHINGTON, DC – December 19, 2012 -- Researchers report for the first time the seroprevalence of three strains of avian influenza viruses in pigs in southern China, but not the H5N1 avian influenza virus.  Their research, published online ahead of print in the Journal of Clinical Microbiology, has implications for efforts to protect the public health from pandemics.

 

Influenza A virus is responsible both for pandemics that have killed millions worldwide, and for the much less severe annual outbreaks of influenza. Because pigs can be infected with both human and avian influenza viruses, they are thought to serve as “mixing vessels” for genetic reassortment that could lead to pandemics, and pigs have been infected experimentally by all avian H1-H13 subtypes. But natural transmission of avian influenza to pigs has been documented only rarely.

 

In the study, from 2010-2012, Guihong Zhang and colleagues of the College of Veterinary Medicine, South China Agricultural University, Guangzhou, People’s Republic of China, tested 1080 21-25 week old pigs for H3, H4, H5, and H6 subtypes of avian influenza virus, and H1 and H3 subtypes of swine influenza virus. Thirty-five percent of the serum samples were positive for H1N1, and 19.7 percent were positive for H3N2 swine flu virus, and 0.93 percent, 1.6 percent, and 1.8 percent were positive, respectively, for the H3, H4, and H6 subtypes of avian influenza A virus. However, no serum samples collected in 2001 were positive for any of these viruses, indicating that transmission into swine was recent.

 

Given the recent transmission of avian influenzas into swine, “We recommend strongly that the pork industry worldwide should monitor the prevalence of influenza in pigs, considering their important role in transmitting this virus to humans,” says Zhang.

 

Previously, novel reassortant H2N3 influenza viruses were isolated from US pigs, which “were infectious and highly transmissible in swine and ferrets without prior adaptation,” according to a 2009 paper in the Journal of Molecular and Genetic Medicine by Wenjun Ma et al. Those viruses resembled, but were not identical to the H2N2 human pandemic virus of 1957.

 

 

The ability of influenza viruses to evolve, mutate, or reassort in swine hosts has been a frequent topic of discussion in this blog.  For more on this, you may wish to revisit:

 

H3N2v: When Pigs Flu

You Say You Want An Evolution?

The (Swine) Influenza Reassortment Puzzle

»» Read More

NSW: Hen Facility Quarantined Under Suspicion Of Avian Influenza

Photo Credit – FAO

UPDATED: I see Crof has picked up a story indicating Australia: Bird flu at chicken farm is H7 strain

 

# 6718

 

While H5N1 gets most of our attention, there are many varieties of avian influenza including H7s and H9s. Some are highly pathogenic (HPAI)  and produce high rates of morbidity and mortality in flocks – while others are of lower pathogenicity (LPAI).

 

The OIE requires their notification whenever an avian influenza of the H5 or H7 strains are identified, because these strains have a history of evolving from LPAI into HPAI strains.

 

We’ve seen many non-H5N1 outbreaks in local poultry operations in places like the UK, Mexico, and Canada. And while exceeding rare, we’ve seen sporadic human infection from these strains as well (see MMWR: Mild H7N3 Infections In Two Poultry Workers - Jalisco, Mexico).

 

If not quickly contained, these outbreaks can force the culling of tens of millions of bird and can inflict devastating economic losses.

 

Today authorities in Australia’s state of New South Wales are reporting a suspected outbreak of an as-yet unidentified avian influenza (not suspected to be H5N1) at a hen facility in the Lower Hunter region.

 

Details are a bit scant, but here is the official release  from the  NSW Department of Primary Industries.

 

Authorities respond to suspect NSW Avian Influenza case

15 Nov 2012

The Department of Primary Industries (DPI) has quarantined a layer hen facility in the Lower Hunter region following a suspect case of Avian Influenza.

 

"The suspected virus is definitely not the highly pathogenic H5N1 strain that has gained worldwide attention — nor is it closely related to that strain," NSW Chief Veterinary Officer Ian Roth said.

 

"Australia has previously had a small number of outbreaks of Avian Influenza viruses which were all quickly and successfully eradicated.

 

"The property has been placed under quarantine and initial tracing and surveillance is being undertaken to confirm that the virus hasn’t spread. We currently have no evidence to suggest it has.

 

"DPI’s First Response Team has been dispatched to monitor the locked-down property."

 

Dr Roth said the peak egg industry body Australian Egg Corporation has been advised and the property owners are co-operating with authorities.

 

"We are still waiting on final confirmation from CSIRO’s Australian Animal Health Laboratory which is expected later this afternoon," Dr Roth said.

 

Dr Roth said people who notice sick or dead birds should contact their local veterinarian or call the Emergency Animal Disease Watch Hotline 1800 675 888.

 

For further information on avian influenza is available.

 

 

Beyond the question of the type of avian influenza at work here will come questions on how this virus was introduced into this flock.  

 

Although Australia has been largely spared from avian influenza outbreaks over the past decade, this is not the first incident reported in 2012.

 

In Janaury a duck farm in Victoria was depopulated due to a LPAI outbreak. Although the strain is not identified in the government press release below, according to the OIE REPORT it was an LPAI H5 strain.

 

Low Pathogenic Outbreak January 2012

6 June 2012

In January 2012 The Department of Primary Industries (DPI) quarantined a commercial duck farm in two locations north-west of Melbourne after birds there tested positive to Low Pathogenicity Avian Influenza (LPAI).

 

To prevent spread of the disease, and in accordance with the Livestock Disease Control Act 1994, the Minister of Agriculture declared Restricted and Control areas around the infected properties in which movement of birds and eggs was restricted.

 

Subsequently, the infected properties were depopulated and decontaminated and the results of surveillance have shown that LPAI is no longer present. On 5th June 2012 the Minister revoked the movement restrictions around the infected properties.

 

 

I’ll post an update to this blog when CSIRO releases their analysis of the strain.

»» Read More

mBio: A Mammalian Adapted H3N8 In Seals

Photo Credit Wikipedia

 

# 6462

Even though the actual study has not appeared online (now online) in the journal mBio, overnight we’ve seen more than a half dozen stories on soon-to-be published research into a novel influenza virus that infected and killed more than 160 seals along the New England coast last year.

 

You’ll find an excellent report from Carl Zimmer in the New York Times (see Flu That Leapt From Birds to Seals Is Studied for Human Threat), as well as this reportage from the BBC (see New flu virus found in seals concerns scientists)

 

Regular readers may recall this story from last fall (see New England Seal Deaths Tied to H3N8 Flu Virus & NOAA: New England Dead Seals Test Positive For Flu), but in brief:

 

In early October of 2011 media reports indicated that scores of dead seals had been discovered along the shoreline of New England, predominantly from the North Shore of Massachusetts to the southern coast of Maine.

 

In November NOAA declared these deaths an “Unusual Mortality Event”, cautioned the public to avoid contact with seals, and directed more resources to study the event.

 

Although the cause of these deaths was still undetermined, some researchers saw similarities to a seal die off that had occurred 30 years earlier.

 

In that instance, the culprit turned out to be an H7N7 influenza. (see Isolation of an influenza A virus from seals G. Lang, A. Gagnon and J. R. Geraci)

 

In December it was announced that the pathogen behind this latest seal die off was a variant of the H3N8 avian flu strain, versions of which are known to also infect horses and dogs.

 

Science team identifies influenza virus subtype that infected five dead seals

Risk to humans and pets low; tests continue

 

Harbor Seals (Credit NOAA)

A virus similar to one found in birds but never before in harbor seals was the cause of five of 162 recent deaths of the animals  in New England, according to a group of federal agencies and private partners.

 

This Influenza A virus subtype, H3N8, appears to have a low risk of transmission to humans. Experts continue to analyze this virus, and any findings of public health significance will be immediately released. The virus is not the infamous H5N1  virus that caused a global pandemic in 2007, or the H1N1 virus from 2009.

(Continue . . . )

 

While we tend to think of humans, pigs, and birds as the main hosts of influenza (and to a lesser extent dogs and horses), a number of other species are susceptible to some kinds of influenza strains as well.

 

• In That Touch Of Mink Flu I wrote about 11 farms in Holstebro, Denmark that were reported to be infected with a variant of the human H3N2 virus back in 2009.
• The AVMA Pandemic Flu page documents species – including dogs, cats, turkeys, skunks, ferrets – that tested positive for the 2009 H1N1 pandemic virus.
• While less commonly reported - camels, whales and seals have all been shown to be susceptible to influenza (cite Evolution and ecology of influenza A viruses R.G. Webster et al.)

 

 

Fast forward eight months and today research is being published to show that the H3N8 virus collected from dead seals last fall has mutated from its avian origins to become better adapted to mammalian hosts. 

 

First stop, excerpts from a press release from the American Society for Microbiology, publishers of mBio.

 

 

New influenza virus from seals highlights the risks of pandemic flu from animals

A new strain of influenza virus found in harbor seals could represent a threat to wildlife and human health, according to the authors of a study appearing July 31 in mBio®, the online open-access journal of the American Society for Microbiology. It is crucial to monitor viruses like this one, which originated in birds and adapted to infect mammals, the authors say, so that scientists can better predict the emergence of new strains of influenza and prevent pandemics in the future.

 

"There is a concern that we have a new mammalian-transmissible virus to which humans haven't been exposed yet. It's a combination we haven't seen in disease before," says Anne Moscona of Weill Cornell Medical College in New York City, the editor of the report.

 

<SNIP>

 

The mBio® study analyzed the DNA of a virus associated with a die-off of 162 New England harbor seals in 2011. Autopsies of five of the seals revealed they apparently died from infection with a type of influenza called H3N8, which is closely related to a flu strain that has been circulating in North American birds since 2002. Unlike the strain in birds, this virus has adaptations to living in mammals and has mutations that are known to make flu viruses more transmissible and cause more severe disease. The virus also has the ability to target a receptor called SAα-2,6, a protein found in the human respiratory tract.

(Continue . . . )

Another press release, from Columbia University's Mailman School of Public Health, titled An avian flu that jumps from birds to mammals is killing New England's baby seals cautions:

 

Based on full genome sequencing and phylogenetic analysis, seal H3N8 descended from an avian strain that has been circulating in North American waterfowl since 2002, which implies recent transmission from wild birds to seals.

 

Accordingly, seal H3N8 has acquired the ability to bind sialic acid receptors that are commonly found in the mammalian respiratory tract. Mutations in the HA and PB2 genes – required for cell entry and replication, respectively – suggest enhanced virulence and transmission in mammals, but these putative attributes require further investigation. Given these findings along with the long history of the spread of avian influenza to humans—most notably H1N1 and H5N1—seal H3N8 could pose a threat to public health.

 

 

Regular readers of this blog are aware that avian influenza strains bind preferentially to the kind of receptor cells commonly found in the digestive and respiratory tracts of birds; alpha 2,3 receptor cells.

 

Human (and mammalian adapted) influenzas – on the other hand - bind to the kind of receptor cells that line the surfaces of the human upper respiratory system; alpha 2,6 receptor cells.

 

 

In both the BBC and NYTs report, one of the authors of this study – celebrated virus hunter Professor Ian Lipkin of Columbia University – expressed concerns over the discovery that seals – like pigs – have both types of receptor cells.

 

If infected by two different strains simultaneously, they could act as a `mixing vessel’ for influenza strains, and produce a hybrid (reassorted) virus. 

 

 

Every day, it seems, we learn more about how remarkably well these influenza viruses evolve and adapt. Despite decades of work by thousands of researchers, there is still so very much we are just beginning to understand.

 

Although the public health threat from H3N8 is hard to quantify, this is yet another example of how Nature’s laboratory is open and operating 24/7, and why we need to remain alert and prepared for the next pandemic threat that may emerge.

 

When the mBio study is published, I’ll post the link here.

 

NOW ONLINE:

 

Emergence of Fatal Avian Influenza in New England Harbor Seals

S. J. Anthony, J. A. St. Leger, K. Pugliares, H. S. Ip, J. M. Chan, Z. W. Carpenter, I. Navarrete-Macias, M. Sanchez-Leon, J. T. Saliki, J. Pedersen, W. Karesh, P. Daszak, R. Rabadan, T. Rowles and W. I. Lipkin

doi:10.1128/mBio.00166-12

»» Read More

Updating Mexico’s H7N3 Outbreak

 

Photo Credit SENASICA

 

# 6432

 

Just over three weeks ago the OIE was notified by Mexico’s Director General of Animal Health Dr Hugo Sanchez Fragoso of an outbreak of highly pathogenic H7N3 avian influenza among poultry in the state of Jalisco (see Mexico: High Path H7 In Jalisco). 

 

A week later, Mexico’s Agricultural Ministry (Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación; SAGARPA) Declared a National H7N3 Animal Health Emergency as the H7N3 virus continued to spread.

 

Map Credit OIE

 

 

Since humans have only rarely been reported to have been infected by this strain of avian flu, the big concern right now is for poultry operations. Cesar de Anda, vice chairman of the International Egg Commission, was quoted by EFE news yesterday as stating:

 

"The industry will fail to produce $50 million, not only from the cost of the (dead) birds, but also from the intrinsic value of production, the generation of wealth and of indirect jobs in other fields."

 

According to Anda, if this outbreak is not brought under control, as many as 32,000 jobs could be at risk.

 

To date, 2.5 million poultry have either died, or been destroyed because of this virus, and according to a press release from SENASICA (Mexico’s Food Safety agency) as many as 17 million birds in the region may be at risk.

 

The latest OIE Filing (Follow-up report No. 3 ) states the source or origin of the virus remains unknown, and provides brief summaries of 31 separate outbreaks. 

 

Under Epidemiological comments, they list:

 

• During the epidemiological surveillance carried out in response to the event, the National Food Quality, Food Safety and Health Service (SENASICA) has taken samples in the outbreaks and around the outbreaks in 148 poultry farms.
• 31 farms were identified by viral isolation, diagnosis is ongoing in other 83 and 34 have tested negative to H7N3 highly pathogenic virus.
• The population at risk in these 148 farms amounts to about 17 million birds, of which 86.1% of layers, 6.9% of broilers and 7% of breeders.
• As part of the measures taken to reduce the risk, the buffer zone has been extended to 60 km around the index outbreak and includes 161 poultry farms at risk with a population of 25.8 million of birds.
• Control measures on birds and their products movements have been strengthened in the quarantine area and eight check points have been established with the support of 26 health technicians with 9 vehicles that monitor the quarantine zone.
• Epidemiological surveillance activities continue in the outbreaks, around the outbreaks and in the buffer zone. As a measure to reduce the risk, sampling will be carried out in neighbouring States and in poultry farms at risk outside the buffer zone.

 

In the first six months of 2012, 14 countries have reported outbreaks of high path avian flu with strains ranging from H5N1 and H5N2 to H7N3. Surveillance and reporting around the world is spotty at best, and so it is likely that we don’t hear about all of the outbreaks.

 

For now, however, these viruses are primarily a threat to the poultry industry, and to a far lesser extent, people working in direct contact with infected fowl.  While H7 viruses have been known to infect humans on rare occasions, most of the reported cases have produced only mild to moderate illness.

 

• In 2003 an outbreak of H7N7 at a poultry farm in the Netherlands went on to infect at least 89 people. Most of the victims were only mildly affected, but one person died.
• In 2004 two people in British Columbia tested positive for H7N3 (see Health Canada Report) during an outbreak that resulted in the culling of 19 million birds.
• In 2006 and 2007 there were a small number of human infections in Great Britain caused by H7N3 (n=1)  and H7N2 (n=4), again producing mild symptoms.

 

For now, H7 avian influenzas are presumed to pose a low public health threat.  But H7s, like all influenza viruses, are constantly mutating and evolving.

 

In 2008 we saw a study in  PNAS that suggested the H7 virus might just be inching towards adapting to humans. For more details on that study, you may wish to revisit H7's Coming Out Party and H7 Study Available Online At PNAS.

 

So, while the H7 virus poses a minimal risk to human health at this time, it pays to keep an eye on outbreaks such as the one in Jalisco.

 

Influenza viruses are constantly changing, and evolving, always seeking an evolutionary advantage. So, what was true about a specific flu virus yesterday, may not hold true tomorrow.

»» Read More

Mexico: High Path H7 In Jalisco

Photo Credit – FAO

 

# 6506

 

 

Last night Lisa Schnirring writing for CIDRAP NEWS  brought us details on the first highly pathogenic bird flu outbreak in Mexico in nearly two decades.  The last time was during the mid-1990s, and the virus was H5N2.

 

This time, the culprit it is H7N3.

 

Follow the link below to read  Lisa’s excellent report, after which I’ll return with a bit more.

 

Tests reveal high-path H7N3 in Mexican poultry farm outbreaks

Lisa Schnirring Staff Writer

Jun 26, 2012 (CIDRAP News) – Mexican veterinary authorities are intensifying avian influenza control efforts in a region that houses several large commercial farms after further tests determined that the strain responsible for more than 200,000 bird deaths at three farms is the highly pathogenic H7N3 subtype.

(Continue . . . )

 

While there are a number of avian flu viruses circulating in the wild, the OIE only requires that H5s and H7s be reported due to their known ability to mutate from a low pathogenic virus to highly pathogenic virus.

 

When it comes to avian influenzas, the H5N1 virus gets the bulk of the headlines, and rightfully so. While a matter of some controversy (see Revisiting The H5N1 CFR Debate), among known human cases, the mortality rate has been a staggering 60%.

 

Other strains that have demonstrated at least some ability to infect humans include H7, H9, H10, and H11. Fortunately, most of the time these rare infections have produced only mild flu symptoms (sometimes only localized conjunctivitis).

 

Last April, in EID Journal: Human Infection With H10N7 Avian Influenza we looked at some recent H10 infections, and in 2011 we explored A Little Background On H11 Avian Influenzas.

 

For now, however, these viruses are primarily a threat to the poultry industry, and to a lesser extent, people working in direct contact with infected fowl.

 

Although global surveillance and reporting on novel avian viruses in humans is spotty at best, some known H7 cases include:

 

• In 2003 an outbreak of H7N7 at a poultry farm in the Netherlands went on to infect at least 89 people. Most of the victims were only mildly affected, but one person died.
• In 2004 two people in British Columbia tested positive for H7N3 (see Health Canada Report) during an outbreak that resulted in the culling of 19 million birds.
• In 2006 and 2007 there were a small number of human infections in Great Britain caused by H7N3 (n=1)  and H7N2 (n=4), again producing mild symptoms.

 

For now, H7 avian influenzas are presumed to pose a low public health threat, which may leave you wondering why all this fuss over this outbreak of H7N3?

 

The H7s, like all influenza viruses, are constantly mutating and evolving.  

 

While considered mild today, there are no guarantees that the virus won’t pick up virulence over time, or reassort with another virus and increase its affinity for humans.

 

Four years ago, we saw a study in PNAS that indicated that the H7 virus might just be moving more towards adapting to humans.

 

Contemporary North American influenza H7 viruses possess human receptor specificity: Implications for virus transmissibility

You can read more about this in a couple of blogs from 2008, H7's Coming Out Party and H7 Study Available Online At PNAS.

 

The last pandemic, you will recall,  came out of left field; from a region of the world (North America), host species (swine), and influenza strain (H1N1) all considered unlikely to spark a global epidemic.

 

Which is why we pay attention whenever there is an outbreak of a novel flu virus for which mankind may have little or no immunity.

»» Read More

EID Journal: Human Infection With H10N7 Avian Influenza

 

 

 

 

# 6261

 

 

Although they are only rarely detected, there is evidence to suggest that humans may be infected by avian influenza viruses more often than is commonly suspected.

 

Every year billions of people around the world experience flu-like symptoms that can stem from any of hundreds of different viruses.

 

Of those, only the tiniest fraction are tested to see what pathogen caused the illness.

 

While most people are aware of the roughly six hundred H5N1 `bird flu’ infections detected over the past decade, we’ve also seen a smaller number of human infections caused by a variety of avian and swine origin flu viruses.

 

 

In 2003, an outbreak of H7N7 at a poultry farm in the Netherlands went on to infect at least 89 people (mostly mildly, but 1 death), and many more may have been infected subclinically.

 

In Egypt - in 2004 -  2 infants were shown to be infected by the H10N7 avian flu virus.

 

In 2006 1 person in the UK was confirmed to have contracted H7N3, and the following year, 4 people tested positive for H7N2 – both following local outbreaks in poultry.

 

But in terms of concern, the closest runner up to H5N1 virus right now is probably H9N2 – which is known to have infected a handful of humans, mostly in Asia.

 

 

During the last half of 2011 we also saw the emergence of a small number of H3N2v swine influenza infections (see H3N2v: Three’s A Crowd) in the United States.  

 

Over the years, we’ve seen a small number of sero-prevalence studies that have looked for (and found) evidence of prior infection by avian influenzas in people exposed to poultry or wild birds, including this one from 2006.

 

Avian Influenza among Waterfowl Hunters and Wildlife Professionals

James S. Gill,* Richard Webby,† Mary J.R. Gilchrist,* and Gregory C. Gray‡

ABSTRACT

We report serologic evidence of avian influenza infection in 1 duck hunter and 2 wildlife professionals with extensive histories of wild waterfowl and game bird exposure. Two laboratory methods showed evidence of past infection with influenza A/H11N9, a less common virus strain in wild ducks, in these 3 persons.

 

 

Interestingly, antibodies to the relatively rare H11N9 virus were detected in these 3 individuals, while antibodies for the far more common H4 and H6 avian viruses (known to circulate in American ducks) were not.

 

One theory that has been suggested is that humans are less likely to develop long-lasting antibodies when exposed to avian-type influenza viruses. 

 

Which brings us to a new study that appears in the May edition of the CDC’s EID Journal that detected the H10N7 avian influenza virus in two poultry abattoir workers in Australia.

 

 

Influenza Virus A (H10N7) in Chickens and Poultry Abattoir Workers, Australia

Article Contents

George G. Arzey , Peter D. Kirkland, K. Edla Arzey , Melinda Frost, Patrick Maywood, Stephen Conaty, Aeron C. Hurt, Yi-Mo Deng, Pina Iannello, Ian Barr, Dominic E. Dwyer, Mala Ratnamohan, Kenneth McPhie, and Paul Selleck

Abstract

In March 2010, an outbreak of low pathogenicity avian influenza A (H10N7) occurred on a chicken farm in Australia. After processing clinically normal birds from the farm, 7 abattoir workers reported conjunctivitis and minor upper respiratory tract symptoms. Influenza virus A subtype H10 infection was detected in 2 workers.

 

 

Although 7 abattoir workers reported symptoms, only 2 tested positive for the H10 virus. The authors write:

 

The conjunctivitis and other reported symptoms among the 7 workers were mild and of short duration, and there was no evidence of seroconversion by hemagglutination inhibition or virus neutralization tests in any of the workers from whom convalescent-phase blood was collected, including the 2 with confirmed influenza A subtype H10 infection.

 

These findings are consistent with the mild symptoms and lack of serologic evidence reported in humans after experimental infection with influenza A (H10N7), which may indicate the limited ability of the virus to multiply and stimulate a detectable immune response in humans (10).

 

Other studies have reported no evidence of elevated subtype H10–specific antibody titers among poultry abattoir workers, although serologic evidence of subtype H10 infection was detected among turkey farmers in the absence of clinical symptoms (11).

 

Although this outbreak was limited, and the symptoms were mild, the abattoir has instituted new policies requiring PPEs (personal protective equipment) for employees who have direct exposure to birds and carcasses.

 

Admittedly, the H10N7 virus would seem an unlikely public health threat.

 

But this study does show that it can infect humans, and that mild or subclinical infections from avian viruses are probably happening that are not being picked up by routine surveillance.

 

When it comes to the next influenza threat, we worry most about H5N1 and H9N2. But the next pandemic virus to successfully jump species could just as easily come out of left field, as we saw in 2009 with the H1N1 swine flu.

 

 

All of which highlights the importance of establishing better global surveillance of humans, and farm animals, for the next emerging influenza virus.

 

Regardless of its strain.

»» Read More

CHP: Update On Avian Influenza Situation In Hong Kong

 

 

 

# 6041

 

 

Via Hong Kong’s Centre for Health Protection, we get the latest on the recent detection of H5N1 in poultry (see Hong Kong: CHP Enhances Human Surveillance For H5N1 for earlier reports) that led to an increase in their alert level to `serious’.

 

The following report comes from this week’s Communicable Diseases Watch dated December 29th. 

 

Communicable Diseases Watch Volume 8, Number 26, Week 51-52 (Dec 11, 2011 – Dec 24, 2011)

 

A few excerpts, but follow the link to read it in its entirety.

 

Update on H5N1 avian influenza

Reported by  MISS  AMY  LI,  Scientific Officer, and  DR ALICE WONG, Senior Medical Officer, Surveillance and Epidemiology Branch, CHP.

Hong Kong has raised the response level under the Government’s preparedness Plan for Influenza Pandemic from Alert to Serious on December 20, 2011. This followed the confirmation of highly pathogenic H5N1 avian influenza virus in a chicken carcass sample taken from the Cheung Sha Wan Temporary Wholesale Poultry Market (Wholesale Poultry Market) on December 20, 2011.

 

The Government is tracing the source of the chicken carcass and it is not certain at this stage whether the chicken came from local farm or was imported. All the poultry at the concerned market have been culled on the following day. The Centre for Health Protection (CHP) has worked with public and private hospitals to enhance the detection of suspected human cases. So far, no human cases have been detected in Hong Kong.

 

Avian influenza infection in human is caused by influenza viruses, such as influenza A H5N1, that mainly affect birds and poultry. Severe infection can result in severe respiratory failure, multi-organ failure and even death. Human infection with H5N1 is a rare event. Most cases recorded to date were sporadic infection, with limited human-to-human transmission in some cases. Below we summarize the latest global and local situation of human H5N1 avian influenza infection.

Global Situation

Figure 1 shows the annual trend of human cases.

(Continue . . . )

 

As is evidenced by the chart above, the number of reported human cases in 2011 is running slightly ahead of what we saw in both 2010 and 2008, with the bulk of the detections coming from Egypt.

 

It is probable that some number of human cases have gone undetected, and so the exact global burden and incidence of the disease in humans is not precisely known.

 

Nevertheless, for now H5N1 is primarily a threat to poultry.

 

The virus remains poorly adapted to human physiology, and despite ample opportunities in places like Egypt, Cambodia, and Indonesia - only appears to cause rare, sporadic infections.

 

The concern, of course, is that over time that may change.  And so the world remains at Pre-pandemic Phase III for the H5N1 virus, and we continue to watch for signs that the virus is adapting to humans.

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New England Seal Deaths Tied to H3N8 Flu Virus

 

 

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We’ve a follow up from NOAA today on the mysterious deaths of seals along the New England coastline earlier this fall.  In early November I reported (see NOAA: New England Dead Seals Test Positive For Flu) that initial tests indicated an influenza A virus, but more testing was needed to determine the exact strain.

In the past, we’ve seen rare and isolated influenza infections resulting in seal deaths from the H7N7 and H4N5 avian flu viruses.

 

Today we learn that the viral culprit in this latest incident is a variant of the H3N8 avian flu strain, versions of which are known to also infect horses and dogs.

 

My thanks to @JustinNOAA for the link to this news release.

 

 

Science team identifies influenza virus subtype that infected five dead seals

Risk to humans and pets low; tests continue

PDF/Print version

Harbor Seals (Credit NOAA)

A virus similar to one found in birds but never before in harbor seals was the cause of five of 162 recent deaths of the animals  in New England, according to a group of federal agencies and private partners.

 

This Influenza A virus subtype, H3N8, appears to have a low risk of transmission to humans. Experts continue to analyze this virus, and any findings of public health significance will be immediately released. The virus is not the infamous H5N1  virus that caused a global pandemic in 2007, or the H1N1 virus from 2009.

 

Any member of the public who sees a seal in distress is reminded to:

• Stay at least 150 feet away
• Keep dogs leashed and away from seals
• Call NOAA Fisheries Service's stranding hotline at 1-866-755-NOAA (6622)

“The work that NOAA and its partners have done to help identify and confirm the virus strain H3N8 in these animals has been an important first step in the investigation into this event,” said Dr. Teri Rowles, lead veterinarian and coordinator of the Marine Mammal Health and Stranding Program for NOAA Fisheries Service. “We are now conducting tests on additional animals to learn more about the role this virus may have played in the die-off and to better understand the virus itself.”

 

Experts believe that Influenza A virus caused a bacterial pneumonia which was responsible for the death of the five seals. Most terrestrial animals infected with the previously known H3N8 virus suffered upper respiratory infections, and most recovered.

 

"This H3N8 virus is usually associated with wild birds, and a separate group of H3N8 infects horses and dogs,” said Dr. Hon Ip, of the USGS’s National Wildlife Health Center. "This is the first time that a virus which is similar to the H3N8 avian influenza virus has been associated with a large scale mortality in marine mammals."

(Continue . . . )

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CDC: Avian Influenza Resource Updates

 

 

# 5993

 

H5N1 Virus – Source CDC PHIL 

 

I’m happy to report that the CDC has updated and/or added a number of avian flu related web pages this week. These resources provide excellent background information along with current thought on the threats posed by avian influenza in birds, humans, and other animals. 

 

After the links, you’ll find an excerpt from the CDC’s risk assessment of the H5N1 avian flu virus.

 

As you’ll see, concerns over it’s adaptation to humans have not diminished.

 

 

• Information on Avian Influenza Monday, December 05, 2011 4:45:00 PM

 

• Avian Influenza in Birds Monday, December 05, 2011 4:45:00 PM

 

• Avian Influenza A Virus Infections in Humans Monday, December 05, 2011 4:45:00 PM

 

• Highly Pathogenic Avian Influenza A (H5N1) Virus Monday, December 05, 2011 4:45:00 PM

 

• Highly Pathogenic Avian Influenza A (H5N1) in Birds and Other Animals Monday, December 05, 2011 4:45:00 PM

 

• Highly Pathogenic Avian Influenza A (H5N1) in People Monday, December 05, 2011 4:45:00 PM

 

• Influenza Type A Viruses and Subtypes Monday, December 05, 2011 4:45:00 PM

 

• Transmission of Avian Influenza A Viruses Between Animals and People Monday, December 05, 2011 4:45:00 PM

 

• Avian Influenza Related Links Monday, December 05, 2011 4:45:00 PM

 

 

As far as the future of avian flu, and the threat it poses to public health, here is what the CDC has to say:

 

 

Assessment of Public Health Threat

 

As the highly pathogenic avian influenza A (H5N1) epizootic (animal outbreak) is not expected to diminish significantly in the short term, sporadic human infections with H5N1 virus, resulting from direct or close contact with infected sick or dead poultry, are expected to continue to occur, including fatal cases. So far, the spread of H5N1 virus from person-to-person has been very rare, limited, and not sustained.

 

To date, there is no evidence of genetic reassortment between human influenza A and H5N1 viruses. However, influenza A viruses circulating among poultry have the potential to recombine with human influenza A viruses.

 

Therefore, this H5N1 epizootic continues to pose an important public health threat. There is little pre-existing natural immunity to H5N1 virus infection in the human population. If H5N1 viruses gain the ability for efficient and sustained transmission among humans, an influenza pandemic could result, with potentially high rates of illness and death worldwide.

 

Human infection with novel or nonhuman influenza A viruses, including influenza A viruses of animal origin, is a nationally notifiable disease in the United States. Human infections with nonhuman or novel human influenza A virus should be identified quickly and investigated to determine possible sources of exposure, identify additional cases, and to evaluate the possibility of human-to-human transmission.

 

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WHO H5N1 Update On Egypt

 

 

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My thanks to Lisa for the head’s up this morning on this World Health Organization Global Alert and Response (GAR)  update from Egypt.

 

 

Avian influenza - situation in Egypt - update 57

29 November 2011 - The Ministry of Health and Population of Egypt has notified WHO of one case of human infection with avian influenza A (H5N1) virus.

 

The case is a 31 year-old female from Meet Salseel district, Dakahlia governorate. She developed symptoms on 10 November 2011 and was hospitalized on 16 November 2011. She is in critical condition and is provided with ventilation support.

 

Investigations into the source of infection revealed that the case had exposure to sick and dead poultry in her backyard.

 

The case was confirmed by the Egyptian Central Public Health Laboratories, a National Influenza Center of the WHO Global Influenza Surveillance Network on 21 November 2011.

 

Of the 153 cases confirmed to date in Egypt, 52 have been fatal.

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Netherlands: H7 Bird Flu Detected

 

 

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Due to its high mortality rate, H5N1 gets most of the world’s attention when it comes to bird flu.  While human infections remain rare, among those diagnosed, roughly 60% succumb to the virus.

 

But H5 isn’t the only avian flu strain we worry about.

 

There are other – less deadly strains – including the H7s, H9s and H11s that have demonstrated the potential to jump to humans.

 

Currently, H5s and H7s are both reportable diseases in poultry, due to their ability to mutate from a low pathogenic virus to highly pathogenic virus.

 

Today, we’ve news of an outbreak of bird flu on a poultry farm near Kapelle, in the Netherlands.  The virus has been identified as H7, but the exact subtype has not yet been established.

 

 

 

First a translation of the statement from the Dutch Ministry of Economic Affairs, Agriculture and Innovation, after which I’ll return with more.

 

 

Bird flu in Zeeland

News item | 03/25/2011

In Zeeland Schore, Chapel congregation is a poultry farm with 127,500 laying hens found bird flu. The H7 is a variant.

 

Because a low pathogenic H7 variant can mutate into highly pathogenic (highly contagious and lethal for chickens variant), the company both a low and a highly pathogenic variant in accordance with European regulations are removed. The new Food Safety Authority to carry out culling on March 25. In the afternoon of March 25 is known whether a low or a highly pathogenic variant,.

 

As of March 25, 2011, is 8.00 hours in an area of ​​one kilometer around the company a ban on transporting poultry, eggs, poultry and poultry manure and litter.

 

The infection probably comes from wild birds excrete the virus in their faeces.

 

 

 

Below you’ll find a chart lifted and edited from CIDRAP’s excellent overview Avian Influenza (Bird Flu): Implications for Human Disease  showing non-H5N1 avian flu infections in humans over the past decade.

 

 

Perhaps the most notorious outbreak of H7 in humans occurred in 2003 in the Netherlands.  It  produced (mostly mild) symptoms in at least 89 people, but did cause 1 fatality. 

 

CIDRAP describes it this way:

 

During an outbreak of H7N7 avian influenza in poultry, infection spread to poultry workers and their families in the area (see References: Fouchier 2004, Koopmans 2004, Stegeman 2004). Most patients had conjunctivitis, and several complained of influenza-like illness. The death occurred in a 57-year-old veterinarian. Subsequent serologic testing demonstrated that additional case-patients had asymptomatic infection.

 

In 2006 and 2007 there were a small number of human infections in Great Britain caused by H7N3 (n=1)  and H7N2 (n=4), again producing mild symptoms.

 

Since surveillance is – at best - haphazard (or even non-existent) in many parts of the world,  how often this really happens is unknown.

 

For now, H7 avian influenzas pose only a minor public health threat. 

 

Since the H7 viruses generally produce mild symptoms in humans, you may be wondering why all the fuss over an outbreak of H7?

 

The H7s, like all influenza viruses, are constantly mutating and evolving.  

 

While considered mild today, there are no guarantees that the virus won’t pick up virulence over time, or reassort with another `humanized’ virus and spark a pandemic.

 

Three years ago, we saw a study in PNAS that indicated that the H7 virus might be moving more towards adapting to humans.

 

Contemporary North American influenza H7 viruses possess human receptor specificity: Implications for virus transmissibility

 

You can read more about this in a couple of blogs from 2008, H7's Coming Out Party and H7 Study Available Online At PNAS.

 

For more on pandemic threats beyond H5N1 you may wish to revisit:

 

It Isn’t Just Swine Flu

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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

USGS: Avian Influenza Update

 

 

 

# 5236

 

 

Every few weeks the USGS National Wildlife Health Center puts together a summary of recent avian flu reports in wild birds, poultry, humans, and other animals reported around the world.

 

You’ll also find an interactive map, showing avian influenza outbreaks around the world, which you can customize by date range, host, and virus types.

 

 

As you can see from the map above – which depicts incidents since December 1st, 2010 – Japan and the Korean Peninsula have seen the bulk of the reported activity.

 

Note: Not all avian influenza activity gets reported.

 

Bird flu outbreaks among poultry in Egypt and Indonesia are so common as to rarely command media notice, and so the mappings of these outbreaks are almost certainly underreported.

 

And there are regions of China, Southeast Asia, and Africa where surveillance and reporting is poor to non-existent.

 

The latest update (a few excerpts appear below) details known AI outbreaks over the past month in wild birds, poultry and humans in Japan, South Korea, Bangladesh, Indonesia, Egypt, and the UK.

 

You’ll also find links to recent scientific articles and publications, and an extensive list of useful AI resources in the sidebar on the right side of the page.

Follow the link to read it in its entirety.

 

 

Avian Influenza Information

News Update, January 14

H5N1 in Wild birds

Japan

According to the Izumi Municipal government, two more hooded cranes (Grus monacha) wintering in the Izumi plain in Kagoshima Prefecture tested positive for bird flu in a preliminary test. So far a total of five cranes are confirmed to be infected with H5N1 bird flu. As of January 4, the city said that it has not seen evidence of massive deaths of wild birds.

 

South Korea. South Korea's farm ministry reported on December 28 that it found 20 dead spectacled teal ducks, apparently infected with H5N1 bird flu, and has taken emergency decontamination measures. The birds were identified as mallards (Anas platyrhynchos) in the official report to OIE, but some veterinarians in the country said they are likely to be Baikal Teal (Anas formosa) instead. The dead birds were found 430 km south of Seoul and were the third group of birds reported dead from H5N1 in South Korea in December.

 

<SNIP>

 

H5N1 in Poultry

Bangladesh. Bird flu broke out on a commercial poultry farm in Dhaka division on January 1, killing 530 birds on a farm of 6500. The remaining birds were culled to prevent the spread of the disease. The origin of the outbreak is unknown, but preventative measures such as stamping out, movement control within the country, and disinfection of the premises have been put in place. Tests by the Bangladesh Livestock Research Institute and the Central Disease Investigation Laboratory in Dhaka were positive for H5N1 bird flu.

 

<SNIP>

South Korea. On December 31, South Korea reported the first outbreak of H5N1 bird flu in domestic poultry in two years. Two poultry farms in South Jeolla province and Chungcheong province first detected bird flu on December 29 as birds began to die off. Together the farms contained a total of 27,850 chickens and ducks. Both farms have been placed under quarantine with authorities moving to cull and bury their ducks and chickens to prevent the disease from spreading.

Quarantine officials had stepped up inspections on wild birds and urged poultry businesses to take extra precautions, like setting up nets around their farms to keep out wild birds, after wild birds were confirmed to have the disease earlier in the month. More than 100,000 birds have been slaughtered in efforts to contain the disease and health authorities placed a quarantine zone over a 10 km (6.25 mile) radius, restricting movements of vehicles and people and carrying out emergency disinfection.

The latest confirmation effectively ends South Korea's bird flu-free status and will halt exports of chickens, ducks and related products. The bird flu outbreak is likely to further strain the country's health system, which has been struggling to contain swine flu and foot-and-mouth disease cases across the country.

 

(Continue . . . )

 

Granted, most of these incidents have already been reported in Flublogia.

 

But this time of year, when we get numerous reports coming in from a variety of regions, it is convenient to find them aggregated and summarized.

 

For more on the Korean story, some recent blogs include:

 

Korea: H5N1 & FMD Outbreaks Continue

South Korea Intensifies Bird Flu Response

S. Korea: Bird Flu Moves North

South Korea Battles Bird Flu, FMD

S. Korea: 3rd Poultry Farm Positive For Bird Flu

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