Assessment of risk associated with influenza A(H5N8) virus

17 November 2016

Background

Avian influenza A(H5N8) viruses have been rapidly spreading, most likely via wild migratory birds in Asia and Europe in recent months, and causing deaths in wild birds and outbreaks in domestic poultry.

Conclusion of current human risk of the avian influenza A(H5N8) virus

Human infection with the A(H5N8) virus cannot be excluded, although the likelihood is low, based on the limited information obtained to date. It should be noted that human infection with A(H5N6) of related clade 2.3.4.4 has already occurred. WHO will re-assess the risk associated with the virus when more information is available.

Understanding of the virus

Geographic distribution in animals:

During 2014, highly pathogenic avian influenza A(H5N8) viruses belonging to clade 2.3.4.4 of the A/goose/Guangdong/1/1996 lineage were detected in wild birds and poultry in China, Germany, Italy, Japan, Netherlands, Republic of Korea, Russian Federation, and the United Kingdom of Great Britain and Northern Ireland. The virus was then detected in North America in late 2014 and was detected sporadically in Canada and the United States of America (USA) in wild birds and poultry until mid-2015. A(H5N8) viruses were also detected in Taiwan, China and in Hungary and Sweden in 2015.



Since June 2016, countries in both Europe and Asia have detected infections in wild birds and/or domestic poultry with A(H5N8) including Austria, Croatia, Denmark, Germany, Hungary, India, Israel, Netherlands, Poland, Russian Federation and Switzerland. Many of these recent detections were associated with mortality in wild birds.



Further spread along the migratory route of wild birds is likely, and introduction into other countries could occur.1

Virology:

Hemagglutinin (HA) and neuraminidase (NA) gene sequences obtained from viruses infecting wild birds in Germany indicate that the recent A(H5N8) viruses are distinguishable from those identified in Europe in 2014 and 2015 but can be grouped with other A(H5) viruses in clade 2.3.4.4, such as the A(H5N8) viruses detected in wild birds in the Tyva region of the Russian Federation during May-June of 2016. While some genetic changes were identified between the German viruses and previously recommended candidate vaccine viruses, more information including phenotypic data is needed to evaluate public health risk of these emerging clade 2.3.4.4 viruses.

Antiviral susceptibility:

NA inhibitor (NAI) susceptibility data from phenotypic assays are available for the A(H5N8) viruses recently detected in the Tyva region of the Russian Federation from May-June 2016. These viruses, which have closely related NA protein sequences to the recently reported A(H5N8) viruses, were shown to be sensitive to zanamivir and oseltamivir by the fluorometric neuraminidase inhibition assay. Available NA sequences from more recent A(H5N8) viruses do not contain any of the amino acid substitutions that are known to confer reduced inhibition in other NA subtypes. However, because the effect of NA amino acid substitutions on NAI susceptibility can differ between NA subtypes, specific studies of the N8 from the these viruses are necessary to determine whether novel substitutions may confer reduced NAI susceptibility. As no matrix gene segment sequence information is available so far from the recently reported A(H5N8) viruses, their susceptibility to adamantine drugs is yet to be assessed.

Human infections:

To date, no human cases of infection with influenza A(H5N8) have been detected. However, human cases of infection with related clade 2.3.4.4 A(H5N6) viruses have been detected and reported in China. Though human infections with A(H5) viruses are rare and generally occur in individuals exposed to sick or dead infected birds (or their environments), they can lead to severe illness or death in humans. Following outbreaks of influenza A(H5N8)/A(H5N2) in the USA, information on individuals with exposure to infected birds was collected, but no evidence of human infection with influenza A(H5) was detected among the persons involved in the study.2

Population immunity:

Based on the available information of other A(H5) subtype viruses, human population immunity against the recently detected A(H5N8) viruses is expected to be minimal.

Transmission in animal models:

Studies of previously isolated influenza A(H5N8) viruses have indicated that the virus does not transmit efficiently in ferrets, which is a model for influenza infections in humans.3,4,5

Disease severity:

Human infections have occurred with another A(H5) clade 2.3.4.4 virus, A(H5N6) since 2014; 6 out of 14 reported cases were fatal.

In summary, given the information at this time, the risk of human infection is low, but cannot be excluded. Of note, other neuraminidase subtypes with 2.3.4.4 clade HA genes are also detected in wild birds and poultry. Continued surveillance for all highly pathogenic avian influenza A(H5) viruses will be important to monitor their occurrence and evolution. Timely sharing of representative viruses and sequence information is critical for a complete assessment of the risk posed by these viruses.

Public health advice</s>PARIS (Reuters) - India has reported an outbreak of a highly contagious bird flu virus in the southwestern state of Karnataka, the World Organisation for Animal Health (OIE) said on Friday, citing a report from the Indian agriculture ministry.

The H5N8 virus was confirmed among birds in the village of Itagi, and all 1,593 of the birds at risk from the disease died or were culled, according to the report posted by the Paris-based OIE.

No details were given on the type of birds or location involved.

The H5N8 bird flu strain has been found in several countries in Europe and the Middle East in recent weeks, leading some states to order poultry flocks to be kept indoors.</s>Bird flu outbreaks have been reported across seven different European countries in the past weeks, with a mixture of 215,928 wild and domestic birds affected.

Since November 12, close to 100 outbreaks of the bird flu disease has been reported to the World Organisation for Animal Health (OIE).

Outbreaks of the highly pathogenic avian influenza have been reported across parts of Hungary, Germany, the Netherlands, Poland, Switzerland, Denmark and Croatia.

The frequency of bird flu outbreaks in Europe have been on the increase since the end of October, with cases seen in wild birds, small farmyard poultry flocks and large scale operations.

Hungary has been the worst affected country by the H5N8 strain of the virus, with commercial flocks of geese, ducks, turkeys and chickens having to be destroyed.

Poultry flocks varying in size from 5,000-40,000 have contracted the disease, while all of the flock must be destroyed in an effort to contain the disease.

Meanwhile, a 36,000 flock of breeding chickens had to be destroyed in Germany following the detection of the disease, OIE reports show.

Different measures have been put in place across Europe to deal with the outbreak of the disease, including movement control inside the country, disinfection and surveillance outside restriction zones.

In an effort to contain the disease authorities are also disposing properly of carcasses, by-products and waste material.

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A common source for the disease outbreak in commercial flocks is contact with wild birds, according to the OIE.

European Commission’s stance on the outbreaks

The European Commission has advised veterinary authorities in affected Member States to take immediate EU control measures when a new outbreak is detected.

It is advised that protection and surveillance zones are established around infected holdings. Urgent protective measures have been adopted in relation to these outbreaks, according to the Commission.

The disease situation and the measures adopted by the Commission are regularly reviewed during the meetings of EU Member State experts.

Laboratory examinations of viruses isolated from wild birds and poultry are continuing the Commission outlined.

As of yet, the investigations into the relevance of the virus for human health has shown that it is still predominantly a bird virus without any specific increased danger for humans, the Commission confirmed.

Danger to Irish Poultry Flocks

Recently, the Chairman of the IFA’s Poultry Committee Nigel Renaghan said that Irish poultry producers shouldn’t be worried about recent outbreaks of bird flu across Europe.

Renaghan believes that the disease is still far enough away not to cause a credible threat in Ireland.

“If we start seeing outbreaks in Scandinavian countries then we should start getting worried, it will come to the north of England and Scotland before it reaches us,” he said.

However, the Irish poultry sector has one of the strongest bio-security levels in Europe, Reneghan said, meaning the opportunities for the disease to be contracted in commercial flocks will hopefully be minimal.</s>HELSINKI (Reuters) - The first confirmed case of H5N8 bird flu has been detected in Finland amid a recent outbreak of the disease in Europe, the Finnish Food Safety authority said on Friday.

The highly pathogenic H5N8 virus was found in wild birds in the Aland islands in the Baltic Sea between Finland and Sweden, the office said in a statement.

The government on Friday ordered poultry farmers to keep flocks indoors to avoid the disease spreading.

Cases of bird flu have been found in a number of countries across Europe in recent weeks, including in Sweden.

(Reporting by Tuomas Forsell; Editing by Hugh Lawson)</s>Chickens are pictured locked in a poultry farm in the Netherlands on November 10, 2016 following the discovery of bird flu among wild birds in Europe

Sweden on Friday said 200,000 chickens were being slaughtered at a farm where bird flu has been detected, following a resurgence in the virus across Europe.

Traces of the H5N8 virus were found at the Aniagra farm in Morarp, southwest Sweden, on Thursday. The discovery came after bird flu was detected among ducks at a tiny farm in neighbouring Denmark, in the Copenhagen region.

"All of the farm's 200,000 hens will be put down to prevent the expansion of the virus," Sweden's agriculture department said in a statement, adding that 37,000 of the birds had already been slaughtered on Thursday.

Government scientist Karin Ahl said the operation would "take time as this is a large farm, above all if one thinks of the crucial disinfection that needs to be done at all of the sites".

Aniagra chief Anders Lindberg told the local newspaper Helsingborgs Dagblad on Thursday: "It's a heavy blow of course, but for the moment what's important is that we do not allow the virus to spread further."

The agriculture department stressed that there is no danger of eating eggs from the farm—or Swedish poultry products in general—as the H5N8 virus has never been transmitted from birds to humans.

The H5N8 virus has been detected in poultry and wild birds in 10 European countries, according to the World Health Organization: Sweden, Denmark, Germany, Austria, Croatia, Hungary, the Netherlands, Poland, Switzerland and Russia.

Last week the Netherlands shuttered petting zoos and banned duck hunting as it stepped up measures to stem its bird flu outbreak, blamed for killing scores of poultry and more than a thousand wild birds.

Explore further 16,000 turkeys killed in Germany to stop spread of bird flu

© 2016 AFP</s>Some 190,000 ducks were destroyed on Saturday at six farms in the Netherlands following an avian flu outbreak, the country's first cull of an epidemic sweeping northern Europe.

Outbreaks of avian flu, primarily the highly pathogenic H5N8 strain, have been reported in Denmark, Finland, Germany and Sweden over the past week.

Dutch authorities did not say what strain of the virus had been discovered at a poultry farm in the village Biddinghuizen, some 43 miles east of Amsterdam.

The cull was implemented at four other sites owned by the same company and at a sixth farm less than a kilometer from the site of the confirmed outbreak.

Officials said they were checking for bird flu at farms within three kilometers of the original site and imposed a ban on transporting poultry products within a six-mile radius.

The world's second-largest agricultural exporter, the Netherlands has more than 100 million hens, pigs, cows and sheep on high-intensity farms. The density makes the animals more vulnerable to disease outbreaks.

Since 1997, 40 million hens, cows, goats, pigs and sheep have been slaughtered to contain outbreaks including swine flu, foot-and-mouth and "mad cow" disease.

The first confirmed case of H5N8 bird flu has been detected in Finland amid a recent outbreak of the disease in Europe, the Finnish Food Safety authority said on Friday.

The highly pathogenic H5N8 virus was found in wild birds in the Aland islands in the Baltic Sea between Finland and Sweden, the office said in a statement.

The government on Friday ordered poultry farmers to keep flocks indoors to avoid the disease spreading.

India has reported an outbreak of the bird flu virus in the southwestern state of Karnataka, the World Organisation for Animal Health said on Friday, citing a report from the Indian agriculture ministry.

The H5N8 virus was confirmed among birds in the village of Itagi, and all 1,593 of the birds at risk from the disease died or were culled, according to the report posted by the Paris-based OIE.

No details were given on the type of birds or location involved.

The H5N8 bird flu strain has been found in several countries in Europe, the Middle East and Asia in recent weeks, leading some states to order poultry flocks to be kept indoors.</s>Some 190,000 ducks have been culled in the Netherlands as part of efforts to stop the spread of bird flu in northern Europe. The highly contagious H5N8 strain has caused outbreaks in Denmark, Germany, Sweden and Finland.

The mass slaughter took place across six farms, after the virus was discovered in the village of Biddinghuizen, around 70 kilometers east of Amsterdam, the BBC reports. The Dutch government has not said which strain showed up.

Authorities said they were going over farms within three kilometers of the original site to check for bird flu, and have now placed a transport ban on poultry products within a ten kilometer radius.

Bird flu, or avian influenza, is an infectious disease of wild birds and poultry that first appeared in South Korea in 2014. The virus later spread to Japan, Europe and North America, with outbreaks reported at poultry farms from 2014 to 2015.

According to scientists, bird flu is carried by migrating birds from Asia going to Europe and North America. The most likely way other birds are contracting the disease is from contact with infected birds or with contaminated droppings.

Most bird flu virus strains don’t infect humans. But hundreds of people have been killed by the H5N1 strain, mostly as a result of contact with infected poultry, either live or dead. There has been no evidence that the virus can infect people through well-cooked birds.

So far, no human cases of H5N8 have been reported. But the World Health Organization (WHO) reminds the public that human infection should not be discounted, although the possibilities are low.

WHO advises people to avoid direct or indirect contact with birds that are sick or found dead, and report such incidents immediately to authorities. In case there has been contact, wash hands thoroughly with soap and disinfectant. Lastly, follow good food safety and food preparation practices to prevent the virus from spreading.</s>RAMPING UP: Picture shows a health worker carrying out spraying at the pelican pond at Delhi zoo, in October. | Photo Credit: V. Sudershan

Health Ministry issues advisory despite the low risk this bird flu strain poses

India has reported an outbreak of a highly contagious bird flu virus in Karnataka, the Paris-based World Organisation for Animal Health (OIE) said on Friday, citing a report from the Indian Agriculture Ministry.

The virus, H5N8, spreads through direct contact with secretions from infected birds, their feed, etc. So far there are no reported cases of H5N8 affecting people. The virus is caused by Type “A” influenza and is a subtype of the H5N1 virus. With nearly 50 ducks dying of the virus last month at Delhi zoo, the State government had issued a health advisory asking people to not consume uncooked chicken or eggs.

In the latest case, in Karnataka, the H5N8 virus was confirmed among birds in the village of Itagi, in Hosapete taluk; all 1,593 of the birds at risk from the disease died or were culled, according to the report posted by the OIE.

No details were given on the type of birds or location involved.

The H5N8 bird flu strain has been found in several countries in Europe and West Asia in recent weeks, leading some states to order poultry flocks to be kept indoors.

The same virus had previously affected livestock in Haryana, Delhi, Madhya Pradesh and Kerala.

Earlier this week, Minister of State for Health Faggan Singh Kulaste had informed the Rajya Sabha that poultry birds in Bellary, Karnataka, had tested positive for H5N8.

“Based on current knowledge, the public health risk to human population is considered low for avian influenza subtype H5N8,” he said.

Mr. Kulaste added that as a matter of caution, the Union Health Ministry has issued an advisory to the States and Union Territories to minimise bird-human interface, ensure that those handling sick or dead birds use personal protective equipment, and also keep them under surveillance.</s>Around 190,000 ducks have been destroyed across six Dutch bird farms in response to an avian flu epidemic.

The action is the first cull by the Netherlands authorities as bird flu sweeps through Northern Europe.

Outbreaks of avian flu, including the extremely contagious H1N1 strain, have been reported in Sweden, Finland, Denmark and Germany.

Dutch authorities have not confirmed which strain of the virus had been discovered at a poultry farm near Biddinghuizen, a village 70km (43 miles) east of Amsterdam.

The cull took place at four other sites run by the same company and a sixth farm less than one kilometre from the site of the original outbreak.

All farms in a three kilometre radius of the original outbreak are being checked for bird flu while a ban has been imposed on transporting poultry products within a radius of 10km.

The Netherlands is the world's second largest agricultural exporter and has more than 100 million hens, pigs, cows and sheep housed in high-intensity farms.

Such densely packed operations makes the animals more vulnerable to disease.

Since 1997, 40 million cows, hens, goats, pigs and sheep have been slaughtered to contain outbreaks of foot-and-mouth disease, swine flu and BSE</s>Outbreaks of avian flu, primarily the highly pathogenic H5N8 strain, have been reported in Denmark, Finland, Germany and Sweden over the past week.

Dutch authorities did not say what strain of the virus had been discovered at a poultry farm in the village Biddinghuizen, some 70 km (43 miles) east of Amsterdam.

The cull was implemented at four other sites owned by the same company and at a sixth farm less than a kilometer from the site of the confirmed outbreak.

Officials said they were checking for bird flu at farms within three kilometers of the original site and imposed a ban on transporting poultry products within a 10-km (six-mile) radius.

The world's second-largest agricultural exporter, the Netherlands has more than 100 million hens, pigs, cows and sheep on high-intensity farms. The density makes the animals more vulnerable to disease outbreaks.

Since 1997, 40 million hens, cows, goats, pigs and sheep have been slaughtered to contain outbreaks including swine flu, foot-and-mouth and "mad cow" disease.
Avian flu virus H5N8 outbreaks are reported in birds in India, Germany, Finland, Ireland, the Netherlands, and several other European nations. The World Health Organization advised on 17 November that human infection is possible, but unlikely, based on information available.