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

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

Avian influenza virus has also previously been detected in predatory mammals such as red foxes, otters, and lynxes on mainland Norway following infection from wild birds.

Sampled in the field
In mid-May, the Veterinary Institute was notified by the Norwegian Polar Institute about the finding 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.
? 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 located and we were able to take samples. We observed no more sick polar bears from the air, says veterinarian and head of wildlife health Knut Madslien.
The samples were then sent to the Veterinary Institute and examined 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.

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

? It is important to monitor the situation to understand the development and manage the risk, says Madslien.


Increased infection pressure in mammals
Most avian influenza viruses are best adapted to transmission between birds. However, mammals can sometimes be infected with avian influenza through direct contact with birds or other mammals that are infected with the virus, whether sick or dead.

The Norwegian Veterinary Institute will conduct further studies of the detected virus to check whether it shows signs of being particularly adapted to mammals.

First detection in polar bear in Europe
In other predators, such as red foxes and lynxes, avian influenza can give clinical signs of brain disease similar to those seen in rabies. Neurological signs such as circling, tilted head posture, paralysis, and reduced fear of humans are common.

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 bears or the polar bear population.