Norway Veterinary Institute Reports HPAI H5N5 In Polar Bears on Svalbard Island - 2nd Polar Bear Reported Aug 25th

[Michael Coston]

Norway Veterinary Institute Reports HPAI H5N5 In Polar Bears on Svalbard Island


Credit: Multiple transatlantic incursions of HPAI
clade 2.3.4.4b A(H5N5) virus into North America
and spillover to mammals

#19,167

Although H5N1 remains the overwhelmingly dominant HPAI H5 subtype reported around the globe, we continue to follow other H5 subtypes bubbling up around the globe.

• Last February, in South Korea: H5N9 Rising, we looked at concerns over the arrival this past winter of a triad of HPAI H5 viruses in Korea; H5N1, H5N6, and H5N9.
• In Mexico, HPAI H5N2 has recently emerged, infecting both humans and poultry (Preprint: Emergence of a Novel Reassorted HPAI A(H5N2) Virus Associated with Severe Pneumonia in a Young Adult).
• Earlier this month China reported their 93rd human infection with HPAI H5N6, which has resulted in 58 deaths (62.4% CFR)
• In both Europe and in Eastern Canada, we've seen sporadic reports of HPAI H5N5 (see Cell Reports: Multiple Transatlantic Incursions of HPAI clade 2.3.4.4b A(H5N5) Virus into North America and Spillover to Mammals) since 2023.
• Additionally, HPAI H5N5 infected and killed a resident of Washington State last November, via contact with backyard birds.

While running a distant 2nd place to H5N1, H5N5 has shown surprising tenacity as it expands its geographic range, and reassorts with other LPAI viruses (see March 2026's Viral Creep: H5N5 Update)

In the summer of 2022, the Norwegian Veterinary Institute reported both H5N1 and H5N5 for the first time in wild birds on Svalbard, which lies above the Arctic circle (see More HPAI (H5N5 & H5N1) Detected In Arctic (Svalbard).

Since then we've been tracking a small - but growing - number of spillovers of H5N5 to mammals in both Europe and Canada, including seals in the UK, domestic cats in Iceland, and raccoons (and other small mammals) in Canada.

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Two summers ago (2024) in Cell Reports: Multiple Transatlantic Incursions of HPAI clade 2.3.4.4b A(H5N5) Virus into North America and Spillover to Mammals, researchers reported finding the mammalian adaptive E627K mutation in a number of samples.​

While we typically see a drop in HPAI reports over the summer, it is because many of their avian hosts have migrated to their high latitude roosting spots - where they may find new opportunities to reassort and evolve -before returning next fall.

All of which brings us to a new report from the Norway Veterinary Institute, which describes the recent detection of HPAI H5N5 virus in both a dead walrus and a polar bear on Svalbard Island.

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Although no other animals were confirmed infected during this investigation, there are eye witness accounts of two other polar bears exhibiting potential neurological symptoms.​

I've reproduced the NVI statement below. Follow the link for additional photos and references.

(Translation)

First detection of avian influenza in polar bears in Svalbard​

Published 19.05.2026​

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The Norwegian Veterinary Institute has detected avian influenza in a one-year-old male polar bear and an adult walrus in Raudfjorden north of Spitsbergen. This is the first time the virus has been detected in polar bears in Norway and Europe.​

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Avian influenza virus was detected in a brain sample from the polar bear.​

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The detected avian influenza virus (HPAI) is of the subtype H5N5, a type of the virus that has also been previously detected in Svalbard: In wild birds in 2022, in a walrus in 2023 and in mountain foxes in 2025. This latest detection is the first in polar bears in Norway and Europe. *​

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Avian influenza viruses have also previously been detected in carnivorous mammals such as red foxes, otters and lynxes on mainland Norway after infection from wild birds.​

Sampled in the field​

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In mid-May, the Norwegian Veterinary Institute was notified by the Norwegian Polar Institute of the discovery of a dead polar bear and a dead walrus in Raudfjorden on Svalbard. The animals were first observed by tourist guides. Two polar bears were also observed in the area showing lameness in their hind legs. This may be a neurological sign, which has previously been observed in polar bears infected with rabies and predators infected with highly pathogenic avian influenza.​

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"This gave us suspicion of a serious infectious disease, and two of us from the Veterinary Institute traveled to Svalbard to assist the Governor with sampling the dead animals in the field. With the help of a helicopter, the carcasses were quickly found and we were able to take samples. We observed no more sick polar bears from the air," says veterinarian and wildlife health specialist Knut Madslien.Walrus carcass on the shore in Svalbard. Despite the walrus being very rotten, it was still possible to detect the bird flu virus in the brain.​

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The samples were then sent to the Veterinary Institute and tested for avian influenza virus and rabies virus. Highly pathogenic avian influenza (HPAI) virus was detected in the samples from both the polar bear and the walrus. Rabies virus was not detected.​

Bird flu virus is circulating in the highlands​

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"The findings are part of a trend where highly pathogenic avian influenza virus is increasingly being detected in mammals in Europe. At the same time, the virus has spread to new areas in recent years, including the Arctic, where it may have consequences for vulnerable populations and ecosystems," explains Ragnhild Tønnessen, avian influenza coordinator at the Norwegian Veterinary Institute.​

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“It is important to monitor the situation to understand developments and manage risk,” says Madslien.​

Increased infection pressure in mammals​

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Most avian influenza viruses are best adapted to be transmitted between birds. However, mammals can sometimes be infected with avian influenza through direct contact with birds or other mammals infected with the virus, either sick or dead.​

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The Veterinary Institute will conduct further investigations of the detected virus to check whether it shows signs of being specifically adapted to mammals.​

First detection in polar bears in Europe​

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In other predators, such as red foxes and lynxes, avian influenza can cause clinical signs of brain disease similar to those seen in rabies. Neurological signs such as circling gait, tilted head position, paralysis, and decreased shyness towards humans are common.​

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Avian influenza virus in polar bears has been scientifically published once before, in a young male polar bear found dead in Alaska in August 2023. It is not known how the virus affects individual individuals and the polar bear population.​

Report if you observe dead or sick animals and birds​

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Both highly pathogenic avian influenza and rabies are serious diseases that can be transmitted to humans. Therefore, it is important to avoid contact with sick animals.​

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If avian influenza is suspected in birds and other animals on the mainland, the Norwegian Food Safety Authority must be notified . If sick or dead animals are observed in Svalbard, it is important that the findings are reported to the Governor .​

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The Norwegian Veterinary Institute is the national reference laboratory for avian influenza and has molecular methods for the detection and characterization of avian influenza viruses.​

https://afludiary.blogspot.com/2026/05/norway-veterinary-institute-reports.html

 

[Michael Coston]

Norwegian Veterinary Institute Reports Another HPAI H5N5 Infected Polar Bear on Svalbard Island​

Credit: Multiple transatlantic incursions of HPAI
clade 2.3.4.4b A(H5N5) virus into North America
and spillover to mammals
#19,310

Although most of the world is primarily concerned with HPAI H5N1, in northern Europe, Iceland, and parts of Canada, a different avian flu subtype - HPAI H5N5 - has been making inroads as well.

Additionally, here in the United States HPAI H5N5 infected and killed a resident of Washington State last November, following contact with backyard birds.

In the summer of 2022, the Norwegian Veterinary Institute reported both H5N1 and H5N5 for the first time in wild birds on Svalbard, which lies above the Arctic circle (see More HPAI (H5N5 & H5N1) Detected In Arctic (Svalbard).


Last May, in Norway Veterinary Institute Reports HPAI H5N5 In Polar Bears on Svalbard Island, we looked at a report of the recent detection of HPAI H5N5 virus in both a dead walrus and a polar bear on Svalbard Island.

Although no other animals were confirmed infected during this investigation, there were eye witness accounts of two other polar bears exhibiting potential neurological symptoms.

Five weeks ago, in Preprint: HPAI H5N5 in a Polar Bear and Atlantic Walrus, Svalbard, 2026, with Widespread Seroconversion in Polar Bears, we saw a report indicating that H5N5 exposure is far more common among polar bears on Svalbard island than previously thought.

Somewhat surprisingly, most polar bears appear to survive H5N5 infection, although severe (and likely neurotropic) illness can occur.

Yesterday the Norwegian Veterinary Institute reported on a second polar bear - recovered in June some 23 km distant from the one found in May - has tested positive for H5N5.

(translation)
Bird flu detected in another polar bear in Svalbard
Published 25.08.2026

The Norwegian Veterinary Institute has detected avian influenza in a young polar bear found dead on the northern tip of Spitsbergen. This is the second time the virus has been detected in polar bears in Norway and Europe.

The detected highly pathogenic avian influenza (HPAI) virus is of the subtype H5N5, a type of the virus that has been previously detected in Svalbard: In wild birds for the first time in 2022 , in a walrus in 2023 , in arctic foxes in 2025 , and in a polar bear and walrus in the spring of 2026. This latest detection is the second in polar bears in Norway and Europe.

Highly pathogenic avian influenza viruses have also previously been detected in carnivorous mammals such as red foxes, otters and lynxes on mainland Norway after infection from wild birds.

Sampled in the field by the District Governor

The polar bear, a young individual, was found dead on Æøya, near Virgohamna. The animal was sampled by the Governor in June 2026, after avian influenza virus was detected in a dead polar bear and a dead walrus in Raudfjorden in May 2026. The distance between the two findings of dead animals is approximately 23 kilometers.

- After the findings on the polar bear and walrus in Raudfjorden, we also recommended sampling the polar bear that was on Æøya, says veterinarian and wildlife health specialist at the Veterinary Institute Knut Madslien.

The samples from the polar bear were then sent to the Norwegian Veterinary Institute and tested for avian influenza virus and rabies. Highly pathogenic avian influenza virus was detected in samples from both the brain and nose. Rabies virus was not detected.

Bird flu virus is circulating in the highlands

"The findings are part of a trend where highly pathogenic avian influenza virus is increasingly being detected in mammals in Europe. At the same time, the virus has spread to new areas in recent years, including the Arctic, where it may have consequences for vulnerable populations and ecosystems," explains Ragnhild Tønnessen, avian influenza coordinator at the Norwegian Veterinary Institute.

- Our researchers, in close collaboration with the Norwegian Polar Institute and other partners, have found that a large proportion of the polar bears examined in Svalbard after 2022 have been exposed to previous avian influenza infection. Although we currently have limited knowledge of the consequences this has for the polar bears, the results indicate that the virus is circulating in the population and that exposure is more widespread than detections in dead animals alone would indicate, says Tønnessen.

Increased infection pressure in mammals

Most avian influenza viruses are best adapted to be transmitted between birds. However, mammals can sometimes be infected through direct contact with sick or dead birds or other mammals infected with the virus.

The Veterinary Institute will conduct further investigations of the detected virus to characterize it more closely and clarify whether it shows signs of being specifically adapted to mammals.

Second detection in polar bears in Europe

In other predators, such as red foxes and lynxes, avian influenza can cause clinical signs of brain disease. Neurological signs such as circling gait, tilted head position, paralysis and reduced shyness towards humans are common.

Avian influenza virus in polar bears has been scientifically published twice previously: In a young male polar bear found dead in Alaska in August 2023 and in a young male polar bear found dead in Raudfjorden on Svalbard in May 2026. However, it is not known how the virus affects individual individuals or the population of polar bears.

– This finding strengthens the indications that highly pathogenic avian influenza virus can also affect polar bears, and that young individuals are particularly vulnerable. This is also consistent with findings in other carnivorous mammals, where the virus mainly affects younger individuals. However, the knowledge base is still very limited and it is important to gain more knowledge about how the virus can affect polar bears, says Madslien.

Report if you observe dead or sick animals and birds

Both highly pathogenic avian influenza and rabies are serious diseases found in Svalbard and can be transmitted to humans. Contact with sick and dead animals should therefore be avoided.

If sick or dead animals are observed on Svalbard, it is important that the findings are reported to the Governor . This is important to obtain an overview of disease incidence and mortality, although it does not always trigger sampling. If avian influenza is suspected in birds and other animals on the mainland, the Norwegian Food Safety Authority must be notified .

The Norwegian Veterinary Institute is the national reference laboratory for avian influenza and has molecular methods for the detection and characterization of avian influenza viruses.

Admittedly, HPAI H5N5 remains a minor player in the world of avian flu, but it has shown remarkable tenacity, persisting and even thriving in some high latitude regions of the Northern Hemisphere.

A recent study (see J. Virology: Risk assessment of avian influenza A(H5N5) virus from the first human case using the ferret model) found that while the Washington State isolate replicated robustly in mammalian cells and caused severe disease, it still lacked adaptations supporting efficient airborne spread.

Six years ago HPAI H5N8 subtype dominated the world's avian flyways, only to be abruptly supplanted by a new and improved H5N1 in 2021.

A reminder of just how quickly the avian flu-scape can change, and why we continue to watch this subtype with interest.


https://afludiary.blogspot.com/2026/08/norwegian-veterinary-institute-reports.html