First Detection of Avian Influenza in a Polar Bear on Svalbard

The Norwegian Veterinary Institute has confirmed the detection of the highly pathogenic H5N5 subtype of avian influenza virus in both the polar bear and walrus. This subtype has previously been detected in wildlife in Svalbard: for the first time in 2022 in wild seabirds, then in a walrus in 2023, and more recently in Arctic foxes in 2025. This latest detection, in a polar bear, is a first for Norway and Europe.

Highly pathogenic avian influenza viruses are also sporadically detected in mammalian predators such as red foxes, otters, and lynx on mainland Norway after spillover from wild birds.

Field investigation

The Norwegian Polar Institute alerted the Norwegian Veterinary Institute after a dead polar bear and a dead walrus were discovered in Raudfjorden, at the northern end of Spitsbergen, Svalbard in mid-May. The animals were first spotted by local tourist guides. In the same area, two additional polar bears were observed showing signs of hindlimb lameness, raising concern amongst experts. While such symptoms can have several causes, they may also indicate neurological disease. Similar signs have previously been reported in a polar bear diagnosed with rabies and are also associated with highly pathogenic avian influenza in predators.

The findings prompted concern that a serious infectious disease could be involved. Two veterinarians from the Norwegian Veterinary Institute travelled to Svalbard to assist local authorities with field investigations and sample collection.

“The carcasses were quickly located following a helicopter flight from Longyearbyen, and samples were successfully collected. We did not observe any additional sick polar bears from the air,” said veterinarian and wildlife health expert Dr. Knut Madslien.

The samples were transported from Svalbard back to the Norwegian Veterinary Institute for analysis for both avian influenza virus and rabies virus. Highly pathogenic avian influenza virus was detected in samples from both the polar bear and the walrus. Rabies virus was not detected.

Avian influenza virus circulating in Arctic regions

“These findings are part of the ongoing spread of highly pathogenic avian influenza in Europe, where the virus is increasingly being detected in mammals. In recent years, it has also expanded into new areas, including the Arctic, where it may impact vulnerable wildlife populations and fragile ecosystems,” says Dr. Ragnhild Tønnessen, avian influenza coordinator at the Norwegian Veterinary Institute.

“It is important that we monitor the situation closely to better understand these developments and manage potential risks,” adds wildlife health expert Dr. Knut Madslien.

Increased infection pressure in mammals

Most avian influenza viruses are primarily adapted to spread between birds. However, mammals can occasionally become infected through direct contact with infected birds or with other infected animals, whether alive or dead.

To better understand the risk, the Norwegian Veterinary Institute will carry out further analyses of the detected virus subtype. These investigations will assess whether the virus shows any signs of adaptation to mammals.

First detection in a polar bear in Europe

In other predators, such as red foxes and lynx, avian influenza can cause clinical signs of brain disease resembling those seen in rabies. Neurological signs such as circling behaviour, abnormal head posture, paralysis, and reduced fear of humans are common.

Avian influenza in polar bears has been scientifically reported only once before, in a young male polar bear found dead in Alaska in August 2023. It is not known how the virus affects individual animals or how it might impact the polar bear population.

Report if you observe dead or sick animals and birds

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

If you suspect avian influenza in birds or other animals on mainland Norway, the Norwegian Food Safety Authority must be notified through this link. If you observe sick or dead animals on Svalbard, report the findings to the Governor of Svalbard through this link.

The Norwegian Veterinary Institute is the National reference laboratory for avian influenza and has molecular methods for detecting and characterizing avian influenza viruses.