Virus
A walrus has been found dead of bird flu on the Norwegian Arctic islands. It is by no means the first mammal species to prove susceptible to the virus.
The dead animal was found last year on Hopen, an island that belongs to the Spitsbergen archipelago. Research in Germany has now shown that the walrus died of bird flu. “This is the first time that bird flu has been detected in a walrus,” Christian Lydersen of the Norwegian Polar Institute told the AFP news agency.
The sample was too small to determine whether it was the H5N1 or H5N8 variant. The virus may have caused several victims among walruses, because six dead animals were found on Spitsbergen last year. According to Lydersen, it is “not unlikely” that they were also ill.
The walrus is yet another marine mammal species that appears susceptible to bird flu. Seals, sea lions and elephant seals have previously been victims, and in December 2023 a polar bear was even found to have succumbed to the virus in Alaska. According to scientists, the virus is still largely spread by birds such as ducks and geese.
In the vast majority of cases, mammals that become infected have come into contact with infected birds – or with their feces. Walruses mainly eat fish and shellfish, but sometimes consume seabirds.
According to Lydersen, it is crucial to monitor the walruses closely because they congregate in the summer months when the ice melts. If walruses still die from bird flu, this would also pose an additional risk to polar bears, which eat the carcasses.
There is worldwide fear that the bird flu virus will become more easily transmitted from mammal to mammal. That would not only make control more difficult, but also increase the risk to humans. So far, only a few dozen people have been infected, but their clinical picture is not too bad.
But a virus can evolve and become more harmful. In addition to marine mammals, farm animals have also been infected in recent years, both poultry and mammals. Earlier this year, several dairy farms in the US were affected. It was an unpleasant surprise that cows could also contract the disease. The virus may have been transmitted from cow to cow.
