Taking HPAI To The Bank (Vole)

Bank Vole – Credit Wikipedia

 

# 10,041

 

For more than a decade a debate has raged on as to how HPAI viruses – like H5N1 – manage to get into so many commercial poultry operations, particularly in South Korea and Japan where farm biosecurity is heavily embraced. 

 

One possibility (as yet unproven) has been that small mammals – like dogs, cats, mice, or voles – are somehow vectoring the virus into commercial poultry flocks.

 

We’ve seen evidence that dogs and cats are both susceptible to H5N1, and of H5N8 Antibodies Detected In South Korean Dogs.  Additionally, we’ve seen H5N1 infections among   civets, raccoons, martens, and – of course – humans.  Scientists have experimentally infected cattle, along with ferrets and mice for testing.

 

A couple of years ago, in H7N9 Transmission and Replication In The Guinea Pig Model, and in 2012’s EID Journal: Guinea Pigs As Reservoirs For Influenza, we saw that the common guinea pig is susceptible to a wide variety of human and avian flu strains.

 

But avian viruses are thought to only rarely jump to mammals. 

 

Avian adapted flu viruses bind preferentially to the alpha 2,3 receptor cells found in the gastrointestinal tract of birds, while mammals typically have mostly alpha 2,6 receptor cells in their upper respiratory tract.   Some mammals – like pigs – have both types of receptor cells, and are therefore more likely to be infected by an avian virus.

 

Frankly,  there’s not been a whole lot of research on the ability for HPAI viruses to infect, replicate, and spread via small wild mammals. But we have a study, published today in the journal Veterinary Research, that undertakes just an experiment using bank voles.

 

Why bank voles, you ask?

 

Well, wild bank voles are likely to inhabit the same areas that wild and migratory birds regularly visit, they have a habit of inserting themselves into barns and farm settings looking for food, and they are already a known vector in Europe for the Puumala virus, a milder form of hantavirus (see Hantaviruses: Of Mice And Men).

 

As we learn from this study, bank voles were not only susceptible to two types of avian flu viruses (H5N1 & H7N1), most were able to carry the virus asymptomatically, shed the virus in copious amounts, and were able to pass on the virus to naïve co-housed sentinel voles.

 

I’ve only included some excerpts from a much longer, fascinating study.  Follow the link to read it in its entirety.

 

Susceptibility to and transmission of H5N1 and H7N1 highly pathogenic avian influenza viruses in bank voles (Myodes glareolus)

Aurora Romero Tejeda^1†, Roberta Aiello^1*†, Angela Salomoni¹, Valeria Berton¹, Marta Vascellari² and Giovanni Cattoli¹

Published: 13 May 2015

© 2015 Romero Tejeda et al; licensee BioMed Central.

Abstract

The study of influenza type A (IA) infections in wild mammals populations is a critical gap in our knowledge of how IA viruses evolve in novel hosts that could be in close contact with avian reservoir species and other wild animals. The aim of this study was to evaluate the susceptibility to infection, the nasal shedding and the transmissibility of the H7N1 and H5N1 highly pathogenic avian influenza (HPAI) viruses in the bank vole (Myodes glareolus), a wild rodent common throughout Europe and Asia.

Two out of 24 H5N1-infected voles displayed evident respiratory distress, while H7N1-infected voles remained asymptomatic. Viable virus was isolated from nasal washes collected from animals infected with both HPAI viruses, and extra-pulmonary infection was confirmed in both experimental groups. Histopathological lesions were evident in the respiratory tract of infected animals, although immunohistochemistry positivity was only detected in lungs and trachea of two H7N1-infected voles. Both HPAI viruses were transmitted by direct contact, and seroconversion was confirmed in 50% and 12.5% of the asymptomatic sentinels in the H7N1 and H5N1 groups, respectively.

Interestingly, viable virus was isolated from lungs and nasal washes collected from contact sentinels of both groups. The present study demonstrated that two non-rodent adapted HPAI viruses caused asymptomatic infection in bank voles, which shed high amounts of the viruses and were able to infect contact voles. Further investigations are needed to determine whether bank voles could be involved as silent hosts in the transmission of HPAI viruses to other mammals and domestic poultry.

<SNIP>

Discussion

The aim of this study was to investigate the susceptibility of the bank vole to infection with two HPAI strains, the H5N1 A/turkey/Turkey/1/2005 (Tk/H5N1) and the H7N1 A/ostrich/Italy/2332/2000 (Os/H7N1) isolates, and to establish whether those avian viruses are transmitted by infected animals to naïve co-housed sentinel voles.

<SNIP>

The present study demonstrated that the bank vole is susceptible to infection with highly pathogenic H5N1 and H7N1 viruses of avian origin without prior adaptation, shedding viable virus in the environment, and transmitting the virus to contact voles. Interestingly, infection with the same HPAI strains demonstrated high pathogenicity and 100% of mortality in BALB/c mice [38], while infected voles were more resistant to the clinical condition and displayed zero or very low mortality rate.

These important findings may suggest that wild rodents could play a role as silent hosts in IA virus epidemiology, contributing to the spread of HPAI virus infections during an outbreak. If this occurs under natural conditions, the circulation of IA viruses in these rodents may provide opportunities for the acquisition of mammalian adaptive mutations, which could minimize the barriers to interspecies transmission of these viruses. However, the study of synanthropic wild mammals, and in particular wild rodents, is a critical and important gap in our knowledge of how IA viruses may evolve in new hosts [22], considering that these species share the same ecological habitats as waterfowl and live commensally around domestic poultry farms [32], thus running the risk of being exposed to IA viruses.

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OIE: New Reassortant HPAI H5N1 In North America

 

# 9608

Yes, you read the title right;  H5N1.  

 

Not the same H5N1 as has been rife in Asia for the past decade, and is currently making trouble in Egypt - but a cousin - a new reassortant H5N1 with genetic components derived from both the Eurasian H5N8 virus (including the H5 HA) and by North American avian viruses. 

 

A more complete description is provided in the OIE report below, after which I’ll be back with more.

 Epidemiology

Source of the outbreak(s) or origin of infection

• Contact with wild species

As part of the increased AI surveillance of wild birds (performed by testing hunter harvested birds), another Eurasian H5 clade 2.3.4.4 virus has been identified through whole genome sequencing of the virus isolate. Introduction of the Eurasian (EA) H5N8 virus into the Pacific Flyway sometime during late 2014 has allowed mixing with North American (AM) lineage viruses and generated new combinations with genes from both EA and AM origin (or “reassortant” viruses) such as the EA/AM H5N2-reassortant detected in Canada and the United States.

Such findings are not unexpected as the EA-H5N8 virus continues to circulate. A novel EA/AM H5N1-reassortant clade 2.3.4.4 was isolated from an American green-winged teal in Whatcom County, Washington.

This H5N1 subtype is different from strain circulating in Asia. The gene constellation is as follows: Eurasian lineage genes (PB2, H5, NP, MP >99% identical to A/gyrfalcon/WA/41088/2014 H5N8); North American lineage genes (PB1 {98% identical to A/Northern pintail/Washington/40964/2014 H5N2}, PA, N1, NS of North American LPAI wild bird lineage. The HA cleavage site is compatible with strains that are highly pathogenic. This novel HPAI EA/AM H5N1-reassortant virus has NOT been found in commercial poultry anywhere in the United States.

 

H5N8 continues to impress in its ability not only to travel rapidly across continents and oceans on the wings of migratory birds, but in the number of viable reassortant viruses it has managed to  spawn along the way.  Last spring, in EID Journal: Describing 3 Distinct H5N8 Reassortants In Korea, we saw early indicators of this virus’s growing diversity, while just last week Taiwan reported two `new’ reassortant viruses (H5N2 & H5N3).

 

Right now we don’t know anything about how this new reassortant virus will behave in poultry (other than being HPAI), or in non-avian species (including humans).  I would posit that there is a good deal of testing & research going on right now to determine that. 

Whether this turns out to be a flash in the avian flu pan, or an early glimpse of a new emerging threat, this report does remind us that influenza viruses are capable of rapid evolution, particularly through reassortment.

 

The number of new avian viruses that have appeared over the past couple of years (H7N9, H5N8, H5N6, H5N5, H5N3, H5N2, H10N8, etc.) illustrate that nature’s laboratory is open 24/7, and one that can easily throw us a nasty curve ball at any time.

Taiwan: HPAI H5N2 Outbreak in Pingtung County

 

 

# 9553

 

Taiwan can be added to the growing list of recent HPAI (highly pathogenic avian influenza) outbreaks in poultry, with word this morning that a large egg farm in Pingtung County – in the far south of the island – has begun culling more than 120,000 birds after the  H5N2 virus was confirmed.

First, this brief notice from Hong Kong’s government:

 

Taiwan's Pingtung eggs ban entry

January 9, 2015

Taiwan authorities announced the outbreak of highly pathogenic H5N2 in Pingtung County subtype of avian influenza, CFS announced immediate entrance to the county's ban eggs.

It should be because of bird flu, the center in November 2012, August 2013 and December last year, has announced a ban on Taiwan and Penghu, Hualien and Ilan egg import ban is still in force.

Centre will closely monitor the OIE news about bird flu outbreak in Taiwan, to act according to the local epidemic.

 

Meanwhile Taiwan's Central News Agency (Focus Taiwan) is reporting:

120,000 chickens to be culled after avian flu confirmed

2015/01/09 19:40:05

Taipei, Jan. 9 (CNA) All of the 120,000 chickens on a farm in Pingtung County will be culled after some have been confirmed infected with highly-pathogenic H5N2 avian influenza, the county government said Friday.

(Continue . . . )

 

Reports suggest that this outbreak may have begun sometime in December, and that eggs have been shipped from the farm after the virus emerged.  Once cooked, however, the virus would be deactivated.

HPAI H5N2 is believed to pose very little risk to human health, although those with long memories will recall that we’ve seen a small number of seroprevalence studies that have found elevated H5N2 antibody titers – particularly among poultry workers.

 

J Epidemiol. 2008;18(4):160-6. Epub 2008 Jul 7.

Human H5N2 avian influenza infection in Japan and the factors associated with high H5N2-neutralizing antibody titer.

Ogata T, Yamazaki Y, Okabe N, Nakamura Y, Tashiro M, Nagata N, Itamura S, Yasui Y, Nakashima K, Doi M, Izumi Y, Fujieda T, Yamato S, Kawada Y.

Arch Virol. 2009;154(3):421-7. Epub 2009 Feb 3.

Serological survey of avian H5N2-subtype influenza virus infections in human populations.

Yamazaki Y, Doy M, Okabe N, Yasui Y, Nakashima K, Fujieda T, Yamato S, Kawata Y, Ogata T.

 

While suggestive of (possibly sub-clinical) prior H5N2 infection (note: other factors might be associated antibody positivity), there is precious little evidence to link any significant or serious human illness to the H5N2 virus. After an earlier HPAI H5N2 outbreak in Taiwan back in 2012 we saw assurances from the WHO: Human Risk From H5N2 Is Low. 

Of course, the caveat holds that influenza viruses are constantly changing.  What was true last year, or even last week, may not hold true forever.

But for now, much like the HPAI H5N8 virus, H5N2 is viewed as primarily a threat to birds, and not to humans.

USDA/APHIS: H5N8 Detected In Oregon Backyard Flock

 

# 9465

 

While not making huge headlines, one of the big stories of the week has been the encroachment of HPAI H5N8 (and HPAI H5N2) into the Pacific Northwest, likely carried in via migratory birds.

 

Just above the border in British Columbia, North America’s first outbreak of HPAI H5 (see CFIA: 11th Poultry Operation Identified With H5N2) - which began nearly 3 weeks ago - continues to plague poultry operations.

 

Today it was announced (h/t Sharon Sanders on FluTrackers) that Oregon is now the second state this week to detect the arrival of these highly pathogenic avian flu viruses (see Tuesday’s OIE/APHIS of HPAI H5N8 & H5N2 Detected In Washington State Wild Birds).   

 

At this point no U.S. commercial poultry operations have been affected, and the risk to human health from these viruses is considered low.  First stop, the Animal and Plant Health Inspection Service (APHIS) release on this latest detection:

 

H5N8 Found in Backyard Poultry in Oregon; Virus not found in commercial poultry in U.S. - No public health concern at this time

 Dec. 18, 2014— The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the presence of highly pathogenic (HPAI) H5N8 avian influenza in guinea fowl and chickens from a small backyard poultry flock in Winston, Oregon. The flock of approximately 100 birds has access to the outdoors. A pond and a marsh on the premises are frequented by migratory birds. The H5N8 virus has NOT been found in commercial poultry anywhere in the United States. There is no immediate public health concern, as the H5N8 virus has been found in birds in other parts of the world and has not caused any human infection to date.

Surveillance for avian influenza is ongoing in commercial poultry operations, live bird markets, and in migratory wild bird populations. Additionally, commercial poultry producers follow strict biosecurity practices and raise their birds in very controlled environments. Birds from the affected backyard flock will not enter the food chain. All poultry, poultry products and wild birds are safe to eat as long as they are properly handled and cooked to a temperature of 165 degrees Fahrenheit. The finding in Oregon was quickly reported and identified due to increased awareness of avian influenza in light of the HPAI H5 findings in wild birds in Washington State earlier this week. This H5N8 virus is the same virus that was found in the Washington State gyrfalcons.

Oregon State officials and USDA are working jointly to respond to this detection, following existing HPAI response plans. The State of Oregon quarantined the affected premises, and APHIS will assist the State in depopulating the remaining birds to prevent the spread of the disease. Additional surveillance of poultry around the infected premises will be conducted as outlined in the response plans. USDA notified the World Organization for Animal Health (OIE) of this detection today as required by the OIE. USDA expects trading partners to respond to this reported detection according to OIE’s science-based standards. USDA is working with trading partners to minimize trade impacts on poultry and poultry products as much as possible.

All bird owners, whether commercial producers or backyard enthusiasts, are encouraged to practice good biosecurity, prevent contact between their birds and wild birds, and to report sick birds or unusual bird deaths to State/Federal officials, either through your state veterinarian or through USDA’s toll-free number at 1-866-536-7593. Additional information on biosecurity for backyard flocks can be found at
healthybirds.aphis.usda.gov USDA is coordinating closely with its partners, including Washington and Oregon State officials, the U.S. Department of the Interior and the U.S. Department of Health and Human Services, on avian influenza surveillance, reporting, and control.

 

Meanwhile, the State of Oregon has released the following statement:

 

News release: Oregon activates avian influenza response plan

News release, Plants, Animals, Insects

December 19th, 2014

24 views

The State of Oregon has activated a multi-agency response plan following the confirmation of highly pathogenic H5 avian influenza in domestic birds in Douglas County. The Oregon Department of Agriculture is the lead state agency responding to the incident, working closely with the Oregon Department of Fish and Wildlife, and Oregon Health Authority. The US Department of Agriculture’s Animal Plant Health Inspection Service (USDA-APHIS) will play a key role in the response as well.

There is no immediate public health concern due to the avian influenza virus detected in Oregon. H5N8 virus has been found in other parts of the world and has not caused any human infection to date. Avian influenza does not affect poultry meat or egg products, which remain safe to eat. As always, both wild and domestic poultry should be properly cooked.

The H5N8 avian influenza virus was confirmed by USDA in guinea fowl and chickens from a small backyard poultry flock in Winston, Oregon. The flock of approximately 100 birds has access to the outdoors. A pond and a marsh on the premises are frequented by migratory birds. The virus has not been found in commercial poultry anywhere in the US. Surveillance for avian influenza is ongoing in commercial poultry operations, live bird markets, and in migratory wild bird populations.

The finding in Oregon was quickly reported and identified due to increased awareness of avian influenza in light of the high path avian influenza findings in wild birds in Washington earlier this week. This H5N8 virus is the same virus that was found in a Washington captive gyrfalcon.

ODA is advising commercial poultry growers and backyard flock owners to be vigilant with biosecurity measures and surveillance.

“Steps are being taken to contain the disease and we have not diagnosed avian influenza elsewhere in Oregon’s domestic poultry population, but the presence of the virus in migratory waterfowl poses a potential risk to our backyard poultry,” says ODA’s State Veterinarian Dr. Brad LeaMaster. “This event underscores the importance of biosecurity for backyard bird owners. We strongly encourage owners to take biosecurity measures to reduce the risk of spreading the disease. That includes preventing contact between their birds and wild birds. We also want them to monitor their flock closely and report sick birds.”

Backyard flock owners can report sick birds to the State Veterinarian’s office at 1-800-347-7028 or can call USDA toll free at 1-866-536-7593.

Oregon’s commercial poultry industry has a robust avian influenza testing program and ODA conducts weekly surveillance testing and health inspections at the state’s only live bird market in Woodburn. In addition, wild bird mortality surveillance is routinely conducted by the Oregon Department of Fish and Wildlife. Wild bird deaths can be reported to the ODFW toll-free line at 1-866-968-260

CFIA Statement: H5N2 Expands To 2 More Farms In BC

Credit CFIA

 

# 9430

 

It’s been less than two weeks since we learned of the outbreak of HPAI H5N2 on two farm in the Fraser Valley region of British Columbia (see Fraser Valley B.C. Culling Poultry After Detecting H5 Avian Flu).  While this H5N2 bird flu strain is highly pathogenic to birds, it is considered to have very low potential for infecting humans.

 

While there were initial hopes that the biosecurity measures in place would limit the impact to these two sites, over past week we’ve seen a slow trickle of reports of other farms in the area affected.   

 

So far this outbreak is nowhere near the scale of what we saw in 2004 with H7N3, but not as well contained as either of the two LPAI H5N2 outbreaks of the last decade (2005 & 2009).  According to a Globe & Mail report last night, more than 150,000 birds have either died or will be culled.

 

The following CFIA (Canadian Food Inspection Agency) report brings the total to 7 farms (with two separate operations on one of the farms), and mentions testing at a 9th facility is underway.  It would not be unexpected if additional sites are identified in the coming days.

 

 

Update on avian influenza situation in British Columbia

December 10, 2014

The Canadian Food Inspection Agency (CFIA) is continuing its investigation into an outbreak of avian influenza in British Columbia's Fraser Valley. As part of this investigation, two additional farms have been identified as having avian influenza.

The province of British Columbia has confirmed the presence of avian influenza on these farms. This identification of additional farms is not unexpected as avian influenza is highly contagious between birds and can spread rapidly. 

Both of these farms are close to one of the initial farms identified as part this outbreak.

The fact that these farms were identified quickly underscores industry's commitment to supporting the response effort by immediately reporting any signs of illness. 

In addition, another barn located on one of the previously-identified infected sites has been confirmed to have avian influenza. As this barn is legally considered a separate business entity, we are treating it as a new infected premises, bringing the total to eight.

The province of British Columbia has also notified the CFIA of another farm where avian influenza is suspected. If confirmed, this would be the ninth infected premises. Testing is underway, and results are expected within the next day.

As part of regular investigation activities, the Agency is fully tracing movements in and out of these sites. This may lead to further premises being identified and depopulated, which would not be unexpected.

Birds have been humanely euthanized on four farms, and depopulation activities have begun on the fifth farm. The remaining farms will be depopulated in the coming days.

The CFIA continues to urge poultry farmers to take an active role in protecting their flocks by employing strict biosecurity measures on their property, and to immediately report any suspicious symptoms to the CFIA.

Avian influenza viruses do not pose risks to food safety when poultry and poultry products are properly handled and cooked. 

The CFIA has mobilized all available resources to manage this situation. The Agency continues to work closely with the Province of British Columbia, the owners of the infected birds, and the poultry industry to manage this outbreak.

For more information on avian influenza and measures poultry farmers can take to protect their flocks, please visit the CFIA web site at inspection.gc.ca.

Date modified:

2014-12-10

CFIA Sets Bird Flu Control Zones In BC

Credit Wikipedia – British Columbia

 

# 9423

 

Last night CFIA  (the Canadian Food Inspection Agency) outlined new steps to control the spread of the HPAI (Highly Pathogenic) H5N2 virus detected last week at 5 poultry operations in southern British Columbia.   

 

Fully half of the province – everything south of Highway 16 – becomes part of the primary control zone.

 

Although no new farms have been announced as infected, surveillance and biosecurity measures will remain elevated for weeks to come.

 

CFIA establishes primary control zone to prevent spread of avian influenza in British Columbia

December 8, 2014

In order to prevent the spread of highly pathogenic avian influenza in British Columbia, the Canadian Food Inspection Agency (CFIA) has established a primary control zone in the area where the disease has been identified.

The Province of British Columbia and the poultry industry support this decision and are working together with the CFIA to implement it.

Avian influenza is highly contagious between birds and can spread rapidly. Because southern British Columbia has a high concentration of poultry operations, the primary control zone covers an area beyond the premises that are currently affected.

The primary control zone is bordered on the west by the Pacific Ocean, on the south by the United States border, on the north by Highway 16, and on the east by the border between British Columbia and Alberta.

The primary control zone is divided into three disease control zones: infected, restricted and security. The three zones represent relative levels of risk and movement restrictions vary accordingly. Most of the restrictions apply to the infected and restricted zones because of the greater potential that the virus can spread.

Within the primary control zone, there are three disease control sub-zones: infected, restricted and security.

• The outer boundary of an infected zone is up to 3 km from any known infected premises.
• The restricted zone is established surrounding the infected zone and measured based on the epidemiology of the disease in order to prevent the spread of avian influenza (3 km to 10 km).
• The security zone is the remainder of the primary control zone (beyond 10 km).

The movement restrictions apply to:

• captive birds (including but not limited to poultry, fowl and pet birds);
• poultry products or by-products;
• anything that has been exposed to captive birds (which could include but is not limited to feed, vehicles, equipment or clothing).

All movement of captive birds in and out of, and through this zone is strictly controlled and requires a permit from the CFIA. The movement restrictions also apply to poultry products and by-products and material that has come into contact with captive birds.

Avian influenza viruses do not pose risks to food safety when poultry and poultry products are properly handled and cooked. Avian influenza rarely affects humans that do not have consistent contact with infected birds. Public health authorities stand ready to take precautionary measures as warranted.

Poultry farmers are urged to take an active role in protecting their flocks by employing strict biosecurity measures on their property, and immediately reporting any suspicious symptoms to the CFIA.

For more information on avian influenza and measures poultry farmers can take to protect their flocks, please visit the CFIA web site at inspection.gc.ca.

Date modified:

2014-12-08

India Orders Massive Cull Over HPAI H5 Outbreak In Ducks

Credit Wikipedia

 

 

# 9369

 

Although the BBC is reporting this outbreak as H5N1 (see India: Kerala orders culling over bird flu fears) the FAO-EMPRES report simply lists the cause as HPAI H5, a designation that is still being used in the majority of media reports coming out of India this morning.

 

Hopefully we’ll see an official statement on the subtype soon.

 

In the meantime, the agricultural minister has order a cull of as many as 200,000 birds and has ordered a halt of transport of ducks or other poultry products from the region. This from Mathrubhumi.com.

Avian flu in Kerala: More than 200,000 birds to be culled

Alappuzha: With the avian flu virus in Alappuzha and Kottayam districts and also in a few panchayats being confirmed, the government will take preventive steps to contain the disease, said ministers V S Sivakumar and K P Mohanan at a joint press meet here on Tuesday.

'We got reports from a Bhopal laboratory that H5 avian influenza virus has been identified in poultry birds in Alappuzha, Kottayam and Pathanamthitta districts. So as a precautionary measure about two lakh birds mostly ducks would be culled starting Tuesday in the affected areas,' Agriculture Minister K.P. Mohanan told reporters after a high-level meeting chaired by Chief Minister Oommen Chandy.

(Continue . . . )

 

The exact subtype, and clade, of this virus is yet to be determined, as it the extent of this outbreak.

 

Although it has been awhile, India is no stranger to seeing bird flu outbreaks, both in domesticated birds and in wild or migratory birds.  The H5N1 virus was first detected on the Indian sub-continent in early 2006, but sparked numerous outbreaks in the 2008-2011 timeframe.

 

Last February, in OIE: H5N1 Detected In Crows Again – India, we saw the latest in a series of terrestrial bird detections that go back to at least 2008.  

Unlike many other countries that have seen outbreaks in poultry, India has yet to report a human infection with the H5N1 virus.

India: HPAI Behind Massive Duck Die Off In Kerala

Credit Wikipedia

 

# 9366

 

With highly pathogenic avian flu turning up in Europe, and continual reports of outbreaks in across much of Asia (see China: H5 AI Rising), we are understandably interested whenever there is a large, unexplained bird die off anywhere in the world.

Last week the Indian press carried reports of a large, and ongoing die off of ducks in Kerala, near Kuttanad – a low lying rice growing region of Southern India - which switches over to duck farming each fall after the rice harvest is in.

 

Based on that report,  there was a die off last spring as well, and a variety of explanations have been offered – including weed killers and chemicals used in the rice paddy.  This fall, however, the die off has accelerated.

 

5,000 Ducks Die of Epidemic in Kuttanad

By Express News Service

Published: 19th November 2014 06:00 AM

(EXCERPT)

Experts from the Department of Veterinary Pathology, College of Veterinary and Animal Sciences, KVASU, Mannuthy, had reported in one of their studies in October that ‘pasteurellosis’ and ‘aflatoxicosis’ had affected the duck population in Kuttanad, and almost 250 ducks died in the outbreak.

But the farmers presented a different picture. They said the disease had killed more than 25,000 ducks in October first week. It had spread to Thakazhi, Edathua, Veeyapuram and other areas in Upper Kuttanad. This time the killer disease has appeared again in November and places like Kainakari, Nedumudi and Mankombu have been affected, they said. 

(Continue . . . )

 

Today the Indian press is carrying word that testing by the National Institute of High Security Animal Diseases has revealed an (undisclosed subtype) highly pathogenic avian influenza virus is behind this die off.  This from the Indian Express.

 

Tests confirm Kerala duck deaths caused by avian influenza

Written by Shaju Philip | Thiruvananthapuram | Posted: November 24, 2014 5:03 pm

Kerala Animal Husbandry Department on Monday said avian influenza virus was behind the massive death of ducks in Kuttanad region of Alappuzha district.

Reports from Alappuzha said 17,000 ducks had died in recent days. Kuttanad is Kerala’s prominent paddy-growing region, where scores of farmers are engaged in rearing duck.

Kerala Animal Husbandry Minister K P Mohanan said preventive steps would be soon initiated to contain the disease. The avian flu was confirmed after lab tests at National Institute of High Security Animal Diseases, Bhopal. He said veterinary kits would be disturbed in the region and if necessary, birds would be culled to prevent the disease’s spread to other regions.

(Continue . . . )

 

The identity of this avian flu has not been disclosed, and as of this writing I’ve found no OIE report published.  Perhaps we’ll learn more later today.

Kerala is an important over-wintering spot for scores of avian species, which flock to the warm tropical wetlands of southern India each fall. 

 

According to The Hindu  2011 report Migratory birds arrive in Kerala, most of these birds hail  from the . . . Eurasia region; Siberia, Mongolia, Kazakhstan and other area north of the Himalayan regions. Some of the birds are also from the Himalayan region.  . . .  The migratory species arriving include godwits, terns, ospreys, golden plovers, pratincoles, several species of ducks and waders like sandpipers and plovers.

There are, admittedly, a number of bird flu strains that could be behind this outbreak.  In recent months we’ve seen the emergence of HPAI H5N8, H5N3, H5N6, H10N8 and new clades of H5N1 and H7N9 (not normally pathogenic in birds) continue to emerge.

For more on this you may wish to revisit these recent related blogs:

FAO On The Potential Threat Of HPAI Spread Via Migratory Birds

Bird Flu Spread: The Flyway Or The Highway?

EID Journal: Subclinical HPAI In Vaccinated Poultry – China

Confirmation Of HPAI H5N8 In The Netherlands

# 9333

 
Although it is a little rough, we’ve a translation of a letter posted on the central government site for the Netherlands (Rijksoverheid.nl) that confirms the subtype of the Highly Pathogenic Avian Influenza discovered on a local Poultry farm as being H5N8.

This comes just 9 days after the announcement of HPAI H5N8 having arrived in Germany.  Prior to that, the highly pathogenic form of that bird flu virus had only been reported in Korea and northeastern China.

 

As I wrote earlier today, in FAO On The Potential Threat Of HPAI Spread Via Migratory Birds, Europe once again appears vulnerable to the introduction of newly emerging avian flu viruses from Asia.

 

 

(machine translation)

 

Letter to Secretary of State Dijksma on the outbreak of bird flu in Hekendorp

Download "Letter to Secretary of State Dijksma on the outbreak of bird flu in Hekendorp"

 

Mr President-In-Office,

On a poultry farm in hekendorp (municipality of Oudewater) is on 15 november JL. an outbreak of bird flu (Avian Influenza, AI) of the H5 variant  established. It concerns high pathogenic avian influenza (HPAI) is of type H5N8. HPAI is  bestrijdingsplichtig in the European legislation.

With this letter I message you about this infection and the measures I have affected.

Monitoring and early warning

In Netherlands are on commercial poultry farms regularly samples taken, which are tested for bird flu (regular monitoring). In Addition There is a system in which veterinarians in certain disease symptoms, that may indicate bird flu, submit samples for research (early warning). For bird flu is a hailing at a suspicion.

Last Friday, 14 november. a poultry farm in hekendorp (municipality of Oudewater) samples submitted because the chicken disease symptoms had that possibly being on bird flu. Yesterday it became clear that it is the H5 variant of avian flu concerned and this morning was after laboratory testing clear that the avian flu virus is the highly pathogenic variant on this company.

Now is also clear that the virus is the type H5N8. This is the same type as has been established in Germany at the beginning of november.

Measures

The RIVM indicates that in rare cases some virus types passing poultry on people. This only happens if there is direct and intensive contact with infected poultry. People who get sick from bird flu get the same symptoms as a normal winter flu, generally expires bird flu in humans mild. To prevent people involved in the culling are protective measures become infected.

It is a legpluimveebedrijf with six stables with a total of around 150,000 laying hens. This company has no outdoor access. Today, Sunday november 16th, is with the culling of the company started. The chickens will be on the company  killed and be drained to destruction. The cull is carried out by the Dutch food and consumer product safety authority (VWA).

The highly pathogenic variant of bird flu is highly contagious for poultry.

This variant is deadly for chickens. Bird flu is a zoonosis, which means that the infection can be transferred from animals to humans.

Because of the high risk of infection is from Sunday 16 november 2014, 11.30 hours a total transport ban (standstill) for poultry and other poultry, eggs, poultry manure and litter from poultry companies set.

This is true for mixed farms with a transport ban pluimveehouderijtak also for other animals and manure of other animals.

In addition to the transport ban is also a guard duty and for poultry and ophok other fowl throughout Netherlands set and applies a visitors scheme on all poultry farms and mixed farms with poultry. Also is there for very Netherlands set up a hunting ban on all animals. Finally, a collect ban poultry and other fowl and exhibition prohibition of force. The obligations also apply to hobby poultry and animal holders other poultry.

European legislation requires that there is a 3 and 10 km area is set (protection and surveillance zone). Currently in force in this area the same measures as in the rest of Netherlands.  In the 10 km area are 16 other poultry farms. These companies be sampled and tested for bird flu. Also be contacts of the company investigated.

The coming days are focused on the origin and spread of the virus to find out and prevent further spread.

I will of course keep you informed of developments.

(signed) Sharon A.M. Denis

State Secretary for Economic Affairs

FAO On The Potential Threat Of HPAI Spread Via Migratory Birds

 

# 9330

 

Although it may sound so very 2006, once again we appear to be faced with a westward expansion of one or more novel avian flu strains out of Asia.  Readers with good memories will recall the scramble in middle of the last decade to prevent the spread, and entrenchment, of H5N1 into Europe (see 2007’s Germany Reports More Infected Poultry & UK: Bird Flu Cull Complete).

 

Between a strict culling policy, and enhanced biosecurity measures, Europe managed to keep H5N1 from becoming endemic in poultry, despite repeated introductions of the virus.

 

China, which has relied predominantly on a vaccination policy, has managed to protect their poultry flocks from excess mortality and morbidity, but – as we discussed last week (see EID Journal: Subclinical HPAI In Vaccinated Poultry – China – now finds itself with multiple clades and subtypes of HPAI in circulation and a roster of poultry vaccines that are slowly losing their effectiveness.

 

While HPAI has proven to be primarily a threat to poultry operations, we have seen hundreds of human infections with both H5N1 and H7N9 (including many fatalities) over the past decade, and scientists worry that either could – over time – adapt better to human physiology and present a pandemic threat. 

 

While H5N1 has a ten-year head start, H7N9 has caused far larger outbreaks over the past couple of years, and is currently viewed as the bigger public health threat.  Upstart viruses such as H5N6, H5N8, and H10N8 are too new to effectively gauge their threat potential, but bear watching (see China: H5 AI Rising).

 

The arrival of H5N8 in Germany last week, and its detection in wild bird feces in Japan this week, along with today’s  report Netherlands: `Severe’ HPAI Outbreak In Poultry, is a reminder that nature’s laboratory is open, and operating 24/7, and that it continues to serve up new disease threats.

 

The role of migratory birds in spreading HPAI has been a controversial one (see Bird Flu Spread: The Flyway Or The Highway?), with wildlife enthusiasts quick to blame the poultry industry, citing poor biosecurity, overcrowded factory farms, and smuggling.  

 

When infected migratory birds land in Japan, or HPAI shows up thousands of miles away from home, it is difficult to ignore the potential role of birds in AI spread.

 

On Friday the FAO published the following report on the potential movement of avian flu viruses out of Asia, and into Europe, via migratory birds.

 

Avian influenza A(H5N8) detected in Europe… a journey to the West?

Germany has become the first European country to report an outbreak of highly pathogenic avian influenza caused by an A(H5N8) virus genetically similar to one spreading in the Republic of Korea since January. The virus causes high mortality in poultry. The route of introduction into Germany remains unclear, but the long-distance spread from Asia to Europe indicates that wild birds may play a role. FAO is emphasizing the need for continued vigilance worldwide and heightened efforts on farms to prevent contact between poultry and wild birds.

What we know

The Federal Republic of Germany officially reported the outbreak on 6 November 2014 to the World Organisation for Animal Health (OIE) and the European Union. German authorities have since contained the outbreak, which occurred on a turkey farm. The Government is working to clarify the source of infection through ongoing epidemiological investigations while also searching for any additional cases through targeted surveillance in the surrounding areas. Genetic information released immediately by the Friedrich Loeffler Institute, the National Reference Laboratory for avian influenza in Germany, shows that this H5N8 is very similar to viruses detected in China, the Republic of Korea and Japan this year.

Akin to the highly pathogenic avian influenza H5N6 virus that emerged in southern China around the same time (see FAO press release, 22 September 2014 and EMPRES Watch, November 2014) this H5N8 originated from various reassortment events involving, among others, HPAI H5N1 viruses circulating in Southeast Asia.
Outbreak data from the Republic of Korea and Germany shows that H5N8 causes high mortalities in chickens and turkeys. Experimental studies with the Korean virus, on the other hand, suggest no associated severe mortality in domestic or wild ducks. However, ducks can shed high amounts of virus (reference).

A role for wild birds?

Much still needs to be clarified about this virus, including how it found its way to Germany. The fact that the virus is genetically close to a virus from the Republic of Korea and that wild ducks may be affected without dying could suggest a role for wild birds in the spread of the virus over long distances and further onward transmission to poultry.

Wild birds were linked previously to the spread of H5N1 HPAI virus from Asia to Europe and Africa from 2005 onwards. With regard to H5N8, experts hypothesize that the virus may have travelled during the spring season from eastern Asia into the breeding grounds of migratory birds in Central Asia. These migratory birds may now be carrying the virus with them as they migrate into more moderate climates.

What this means

The detection of H5N8 in Europe is a reminder that avian influenza viruses still represent a global threat to animal health and the international poultry industry. FAO is calling for worldwide vigilance and targeted surveillance as well as optimized biosecurity measures on farms. Avian influenza spreads most easily from infected farms to uninfected farms through common processes involved in the poultry industry and where biosecurity is low. Reducing direct and indirect contact between poultry and wild birds is an important part of good biosecurity, especially in light of various virus strains that may be carried by wild birds.

Experimental infections with H5N8 demonstrate the Republic of Korea show that certain aquatic wild bird species, like mallards, may not exhibit overt signs of disease or mortality. Likewise, the virus may not cause high mortality in domestic ducks. Therefore, active surveillance is important for early detection both in aquatic wild birds and in poultry.

What FAO suggests

• Any significant increase in mortality, neurological signs or reductions in food intake or egg production in ducks and chickens should be immediately reported and investigated.
• Any unexplained excess mortality in wild birds, especially aquatic species, should be fully reported and investigated.
• Poultry should be kept indoors with good standard biosecurity measures implemented on farms aiming at minimizing contact with wild birds as well as between poultry farms.
• Hunters should properly dispose of any remains from hunted wild birds. Hunters should also avoid contact with domestic poultry during or directly after hunting.

Netherlands: `Severe’ HPAI Outbreak In Poultry

Hekendorp – Credit Wikipedia

 

***  UPDATED ***

Reuters is now reporting the subtype has been identified as HPAI H5N8, the same strain that was reported at a German Poultry Farm 10 days ago.

 

 

# 9329

 

From the central government site for the Netherlands (Rijksoverheid.nl) this morning we get the first official statement on a large outbreak of Highly Pathogenic Avian Flu (HPAI) at a poultry farm in Hekendorp, which has resulted in the immediate culling of 150,000 chickens.

 

Although the exact subtype is not identified, this statement calls this outbreak `severe’, `very contagious among poultry’ and a zoonotic risk to human health. 

 

This is the second high profile HPAI outbreak in Europe in just over a week (see Germany Reports H5N8 Outbreak in Turkeys), and while we don’t know if these two are related, the recent surge in the number of newly emerging avian flu strains in Asia (H7N9, H5N6, H5N3, H5N8, H10N8) has all of Europe’s poultry industry on alert.

This strongly worded announcement from the Dutch Economic Ministry.

 

Severe bird flu in Hekendorp

News | 16-11-2014

This morning has been determined that the bird flu highly pathogenic variant appears at a poultry farm in Hekendorp (municipality Oudewater) are. The highly pathogenic strain of avian influenza is very contagious among poultry. This version is for chickens fatal. Avian flu is a zoonosis, which means that contamination of the animal can be transmitted to humans. Protective measures for that reason made for people who can come into direct and close contact with infected poultry. A temporary standstill for poultry and mixed farms with poultry also proclaimed in the Netherlands.

As reported yesterday, the company is cleared. It is a six poultry houses with a total of around 150,000 laying hens. This company has no outdoor access. The depopulation is by the Dutch Food and Consumer Authority (NVWA).

Standstill poultry transport throughout the Netherlands

From Sunday, November 16th, 2014 at 11.30 am a total transport ban applies to poultry and other poultry, eggs, poultry manure and used bedding from poultry farms. For mixed farms with poultry applies these bans also for other animals and manure from other dierenvan those companies. This prohibition applies to up to 72 hours. Is also a ophok- and cover requirement for poultry and other poultry in the Netherlands set. For this period , this standstill period set Due to the high risk of infection. In this period also applies a rating scheme on all poultry farms and mixed farms with poultry. Also applies to the Netherlands a ban on hunting the animals. Too, and a collective exhibition ban ban for poultry and other birds. The obligations also apply to hobby farmers of poultry and other birds.

For poultry farms in a zone of 10 kilometers around the holding in Hekendorp physical movement of poultry, eggs, poultry manure and used bedding applies in principle to 30 days. Within this area are 16 other poultry farms. The restrictions also apply to mixed farms with poultry. The ban also applies here for other animals from other animals. And manure These companies are sampled and tested for bird flu. For these companies, applies to this period a visitor control and should also be extra hygiene observed here.

 

As we saw repeatedly in 2006 and 2007 with the introduction of H5N1 into Europe, the arrival of HPAI to countries where it is not endemic can cause considerable economic and public health concerns. We’ll be waiting eagerly to see what subtype of avian influenza is involved.

 

For more on the rise of new flu strains in Asia, and the ability of migratory birds to carry this virus to countries thousands of miles away, you may wish to visit these recent blogs:

 

China: H5 AI Rising

FAO-EMPRES Report On The Emergence And Threat Of H5N6

Bird Flu Spread: The Flyway Or The Highway?

Japan: H5N8 In Migratory Bird Droppings

EID Journal: Subclinical HPAI In Vaccinated Poultry – China

Photo Credit – FAO

 

# 9315

 

Yesterday’s EID Journal carries an important dispatch that looks at a topic we’ve discussed several times over the years; the downsides to relying solely on poultry vaccines for the control of Highly Pathogenic Avian Influenza (HPAI) (for earlier blogs see OIE: Countries That Vaccinate Poultry Need An `Exit Strategy' & Food Insecurity, Economics, And The Control Of H7N9).

 

For years countries have been deeply divided on this issue – with most of Europe, North America, and the rest of the developed world favoring the immediate culling of infected birds – while China, Vietnam, Indonesia, Egypt, and a handful of of other nations have come to rely almost completely on vaccines.

 

The problem has been that while vaccines can often protect poultry against illness - with increasingly diverse and rapidly evolving avian flu viruses - they cannot always prevent infection.  The end result being that subclinical infections can go undetected, viruses continue to circulate, and new variants or reassortants continue to emerge.  

 

The chart below illustrates just some of the diversity among H5N1 strains that has emerged over the years.

Credit WHO

While quarantine and aggressive culling is the recommended HPAI control strategy, for countries with high food insecurity and a heavy reliance upon poultry, vaccines have been an attractive option. Whether factory farmed or just backyard flocks, poultry represents a major source of income, protein, and accrued wealth for hundreds of millions of people.

 

Erode that in any significant way through culling, and you risk destabilizing an entire region. For China, which has been ground zero for avian flu viruses, vaccination was viewed as being their only recourse.

 

According to 2012’s Impact of vaccines and vaccination on global control of avian influenza by David Swain, more than 113 billion poultry vaccine doses were used from 2002 to 2010. Five countries accounted for 99% of vaccine used: 1) China (90.9%), 2) Egypt (4.6%), 3) Indonesia (2.3%), 4) Vietnam (1.4%), and 5) Hong Kong Special Administrative Region (< 0.01%).

 

The OIE (World Organization For Animal Health) has been long aware of the potential of vaccines to hide infection, warning that vaccination of poultry cannot be considered a long-term solution to combating the avian flu virus. In 2013, the OIE reiterated this advice in Questions and Answers on influenza A(H7N9), stating:

 

Does OIE recommend vaccination of animals to control the disease?

When appropriate vaccines are available, vaccination aims to protect the susceptible bird populations from potential infection. Vaccination reduces viral excretions by animals and the virus’ capacity to spread. Vaccination strategies can effectively be used as an emergency effort in the face of an outbreak or as a routine measure in an endemic area. Any decision to use vaccination must include an exit strategy, i.e. conditions to be met to stop vaccination.

 

In 2009 we saw Professor C.A. Nidom, of the Institute of Tropical Disease, Airlangga University, Indonesia warn on relying on poultry vaccines to control Indonesia’s bird flu problem (see Indonesia: Debate Over Poultry Vaccination), and  Zhong Nanshan, a hero of the SARS outbreak and respiratory disease specialist in China, warned that vaccinated poultry can still become infected (and possibly transmit) the H5N1 virus.

 

Chinese expert issues new bird flu warning

www.chinaview.cn 2009-02-06 17:59:50

GUANGZHOU, Feb. 6 (Xinhua) -- A leading Chinese expert on respiratory diseases has warned the public to be aware that poultry can be infected with the bird flu virus but show no symptoms.

"Special attention should be paid to such animals, including those that have been vaccinated," said Zhong Nanshan.

"The existing vaccines can only reduce the amount of virus, rather than totally inactivating it," he said.

(Continue . . . )

 

While China’s poultry vaccination policies can be credited with reducing poultry losses, promoting better food security, and probably reducing human infections,  the costs of administering vaccines to billions of birds - often several times a year - is enormous, and at the same time the effectiveness of the vaccines continues to decline.

 

China now faces a classic Catch-22 situation.

 

To shift abruptly away from vaccines and go to a strict `quarantine & cull’  strategy would almost certainly result in massive HPAI outbreaks, which could conceivably collapse their poultry industry. But if changes aren’t implemented – and probably soon -  at some point the vaccines available will no longer be able protect the industry.

 

All of which serves as prelude to a dispatch, published yesterday in the EID Journal, that looks for (and finds) subclinical HPAI infection in vaccinated Chinese poultry, and – as has been long feared - that mass vaccination is likely driving the creation of vaccine-escape variants.  

 

Volume 20, Number 12—December 2014

Dispatch

Subclinical Highly Pathogenic Avian Influenza Virus Infection among Vaccinated Chickens, China

Qing-Xia Ma, Wen-Ming Jiang, Shuo Liu, Su-Chun Wang, Qing-Ye Zhuang, Guang-Yu Hou, Xiang-Ming Liu, Zheng-Hong Sui, and Ji-Ming Chen

Abstract

Subclinical infection of vaccinated chickens with a highly pathogenic avian influenza A(H5N2) virus was identified through routine surveillance in China. Investigation suggested that the virus has evolved into multiple genotypes. To better control transmission of the virus, we recommend a strengthened program of education, biosecurity, rapid diagnostics, surveillance, and elimination of infected poultry.

Highly pathogenic avian influenza (HPAI) type A viruses of the subtype H5 have been circulating among poultry in several countries of Asia and Africa for many years. HPAI viruses of this subtype have also caused hundreds of infections among humans and presented a substantial threat to public health (1,2). China is one of the countries deeply affected by zoonotic viruses of this subtype (3). The government of China decided during 2005 to use a comprehensive strategy to control this zoonosis involving mass vaccination of poultry and strict culling of infected flocks (2).

Although this strategy has played a successful role in guaranteeing safety of food supplies, maintaining the poultry system, and minimizing human infections, governmental agencies in China are considering how to exit from mass vaccination programs, mainly because of the tremendous cost of this intervention. We report here an investigation of recent subclinical circulation of the HPAI virus among egg-laying chickens on a farm in China, to provide novel data and views on the evolution of the virus and improvement of HPAI control in China.

<SNIP>

Conclusions

HPAI mass vaccination played a crucial role in HPAI control in China. However, this study demonstrated multiple disadvantages of HPAI mass vaccination, which had been suspected (13,14). For example, this study showed that H5N1 subtype HPAI virus has evolved into multiple H5N2 genotypes, which are all likely vaccine-escape variants, suggesting that this virus can easily evolve into vaccine-escape variants. This observation suggests that HPAI mass vaccination, which is highly effective in the beginning of an outbreak, may lose its effectiveness with time unless the vaccine strains are updated. Moreover, this study showed that vaccinated chicken flocks can be infected with vaccine-escape variants without signs of illness. Thus HPAI mass vaccination may increase shedding of the virus by infected chickens that otherwise would likely exhibit signs of illness and die soon after infection; therefore, HPAI mass vaccination may increase spread of a virus that otherwise would be easily identified by observation of clinical signs.

Currently, HPAI mass vaccination in poultry should not be stopped; otherwise, many HPAI outbreaks could likely occur in poultry farms with limited biosecurity. Conversely, HPAI mass vaccination in China can not be expected to have a progressive effect because the practice leads to silent spread of vaccine-escape variants selected in the host immunologic pressure induced against vaccine strains. We propose that the only way out of this dilemma is to strengthen the strategy published previously, which covers the following components: education, biosecurity, rapid diagnostics and surveillance, and elimination of infected poultry (14). Mass vaccination should be used as an additional tool within this 4-component strategy, not in place of the 4 components.

 

 

Although China is both the biggest producer of poultry, and the biggest consumer of poultry vaccines, the problems cited above are not unique to China.  Egypt, Vietnam, and Indonesia have all reported vaccine failures in the past (see FAO Warns On Bird Flu & Egypt: A Paltry Poultry Vaccine) and may face similar hard choices in the future.

 

For more on the steep rise in new H5 variants and subtypes in China, you may wish to revisit:

 

China: H5 AI Rising

FAO-EMPRES Report On The Emergence And Threat Of H5N6

PLoS One: North Atlantic Flyways Provide Opportunities For Spread Of Avian Influenza Viruses

Global Flyways – Credit FAO 

 

# 8389

 

It is pretty clear from the way the HPAI H5N1 virus spread out of South East Asia to Europe and the Middle East in the middle of the last decade, that migratory birds can play a major role in its dissemination.  These birds can often carry avian influenza viruses without ill effect, and when they encounter other birds, can `share’ their viral cargo along their migratory flyway.

 

Where flyways overlap, there is a greater chance of spreading a virus from one region to another. And as you can see by the map above, they overlap a lot.

 

Japan and Korea – both overwintering sites for migratory birds that summer in Asia and Siberia – have seen the seasonal arrival of H5N1 in years past (see What Goes Around, Comes Around), and this winter Korea has found itself battling a viral  foe: H5N8.  Again, thought to have been introduced by migratory birds from China (see Korea: Migratory Birds Likely Source Of H5N8 Outbreak).

 

While the HPAI viruses originating in Asia have yet to make it to North America via these migratory birds, the concern remains that it could happen.   Accordingly, the Pacific Flyways have been viewed with the most interest, as this would be the most direct route for H5N1, H7N9, or H5N8 to jump to the Americas.   

 

But European birds can carry HPAI viruses as well, and new reassortant viruses can emerge anywhere, not just in Asia (see EID Journal: Predicting Hotspots for Influenza Virus Reassortment). 

Reassortment of two Avian Viruses Producing a Hybrid (Reassortant) Virus 

 

So while less obvious a threat, the North Atlantic Flyways are considered a potential air-bridge for the introduction of new (or components for a reassorted) virus to North America.  Yesterday, the open access journal PLoS One published a study funded by the USGS and NIAID that confirms this potential.  

First the press release from the USGS, then a link to the study and some excerpts. I’ll have a bit more after.

 

North Atlantic May Be a New Route for Spread of Avian Flu to North America

Released: 3/19/2014 5:10:00 PM

The North Atlantic region is a newly discovered important pathway for avian influenza to move between Europe and North America, according to a U.S. Geological Survey report published today.

USGS scientists and Icelandic partners found avian flu viruses from North America and Europe in migratory birds in Iceland, demonstrating that the North Atlantic is as significant as the North Pacific in being a melting pot for birds and avian flu. A great number of wild birds from Europe and North America congregate and mix in Iceland's wetlands during migration, where infected birds could transmit avian flu viruses to healthy birds from either location.

By crossing the Atlantic Ocean this way, avian flu viruses from Europe could eventually be transported to the United States. This commingling could also lead to the evolution of new influenza viruses. These findings are critical for proper surveillance and monitoring of flu viruses, including the H5N1 avian influenza that can infect humans.

"None of the avian flu viruses found in our study are considered harmful to humans," said Robert Dusek, USGS scientist and lead author of the study. "However, the results suggest that Iceland is an important location for the study of avian flu and is worthy of special attention and monitoring."

The study also highlighted the new finding that gulls play an important role in moving avian flu viruses across the North Atlantic.

During the spring and autumn of 2010 and autumn of 2011, the USGS researchers and Icelandic partners collected avian influenza viruses from gulls and waterfowl in southwest and west Iceland (see map). By studying the virus’ genomes — an organism’s hereditary information — the researchers found that some viruses came from Eurasia and some originated in North America. They also found viruses with mixed American-Eurasian lineages.

"For the first time, avian influenza viruses from both Eurasia and North America were documented at the same location and time," said Jeffrey Hall, USGS co-author and principal investigator on this study. "Viruses are continually evolving, and this mixing of viral strains sets the stage for new types of avian flu to develop."

(Continue . . . )

 

Excerpts from PLoS One:

 

North Atlantic Migratory Bird Flyways Provide Routes for Intercontinental Movement of Avian Influenza Viruses

Robert J. Dusek mail, Gunnar T. Hallgrimsson, Hon S. Ip, Jón E. Jónsson, Srinand Sreevatsan, Sean W. Nashold, Joshua L. TeSlaa, Shinichiro Enomoto, Rebecca A. Halpin, Xudong Lin, Nadia Fedorova, Timothy B. Stockwell, Vivien G. Dugan,  [ ... ], Jeffrey S. Hall

Abstract

Avian influenza virus (AIV) in wild birds has been of increasing interest over the last decade due to the emergence of AIVs that cause significant disease and mortality in both poultry and humans. While research clearly demonstrates that AIVs can move across the Pacific or Atlantic Ocean, there has been no data to support the mechanism of how this occurs. In spring and autumn of 2010 and autumn of 2011 we obtained cloacal swab samples from 1078 waterfowl, gulls, and shorebirds of various species in southwest and west Iceland and tested them for AIV. From these, we isolated and fully sequenced the genomes of 29 AIVs from wild caught gulls (Charadriiformes) and waterfowl (Anseriformes) in Iceland. We detected viruses that were entirely (8 of 8 genomic segments) of American lineage, viruses that were entirely of Eurasian lineage, and viruses with mixed American-Eurasian lineage. Prior to this work only 2 AIVs had been reported from wild birds in Iceland and only the sequence from one segment was available in GenBank. This is the first report of finding AIVs of entirely American lineage and Eurasian lineage, as well as reassortant viruses, together in the same geographic location. Our study demonstrates the importance of the North Atlantic as a corridor for the movement of AIVs between Europe and North America.

Discussion

In this study we isolated 11 unique AIVs in gulls and waterfowl from Iceland that contained unexpectedly high viral genetic diversity. Most significantly, we obtained viruses that were completely (all 8 segments) of Eurasian lineage or American lineage as well as reassortant American and Eurasian lineage viruses. Previous to this study there have been no reports of complete American or Eurasian lineage viruses in the same geographic location [12], [25].

When Eurasian AIV segments have been detected in the Americas, or American AIV segments in Eurasia, it has generally been only 1 or 2 segments per virus [12], [18], [19], [25]. However, 2 recent studies in North America have found viruses with near complete (7 of 8 segments) Eurasian lineage genomes [16], [19]. Both of these studies were conducted in regions where predominately Eurasian flyways overlap into North America (the East Asian Flyway and the East Atlantic Flyway). Iceland is within the East Atlantic Flyway (Figure 2); this flyway extends into North America (Greenland and eastern Canada) and tens of thousands of migratory birds move from North America into Europe along this route on their way to and from breeding and non-breeding grounds [31], [32].

Our data demonstrate that the North Atlantic serves as a route for intercontinental movement of AIV and it will be important to track the further dissemination of these viruses, in whole, or in part, into the Icelandic avian community and, more significantly, into the avian communities of Europe or North America.

(Continue . . . )

 

While we’ve seen a lot of evidence to support the idea that migratory birds play an important role in the spread of avian viruses, not everyone agrees. 

 

Last month in Korea: H5N8 Spreads, Debate Over Source Intensifies, the Scientific Task Force on Avian Influenza and Wild Birds argued against migratory birds being the source of that virus in Korea.  Similarly, in years past we’ve seen other experts decry the blaming of migratory birds in the spread of H5N1 (see India: The Role Of Migratory Birds In Spreading Bird Flu & Another Migratory Bird Study).

 

Despite these somewhat partisan assertions, there have been plenty of other studies that strongly associate migratory birds with the spread of avian flu viruses. 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

 

Whether this North Atlantic flyway will provide a route for new HPAIs to show up in the Americas is unknown, but it does illustrate the folly in becoming too focused on one area of the world, when others are perfectly capable of serving up a viral surprise.