Norwegian researchers report that the first case of a walrus infected with an avian flu virus has been discovered. The walrus was found last year next to six others on the island of Hopen in the Svalbard archipelago, Christian Lydersen from the Norwegian Polar Institute told the press.
According to the researcher, tests carried out by a German laboratory had confirmed the presence of a pathogen. The sample was too small to determine whether it was the H5N1 or H5N8 strain, an important aspect. This is because H5N1 exists in a highly contagious variant (HPAI), which has been detected in numerous marine mammals in the southern hemisphere, in a polar bear in Alaska and thousands of cows in the USA and is also held responsible for most human deaths, while H5N8 has been detected primarily in birds and in a few humans. Nevertheless, Christian Lydersen says: “This is the first time that bird flu has been detected in a walrus.
Around six dead walruses were officially found on the archipelago last year. Lydersen told the press that it was “not unlikely” that some of them had contracted bird flu.
Based on this evidence, the authorities should now pay more attention to walruses. This is because the largest seals in this part of the Arctic tend to congregate in groups during the summer months. Walruses could infect each other. There is also a risk that a polar bear could eat an infected walrus carcass and thus affect another species.
Despite the result, experts are still less concerned. Frank Wong, a molecular microbiologist at the CSIRO (Australian Animal Health Laboratory), told the press that bird flu is still an avian-adapted virus transmitted by birds such as ducks and geese. The sporadic infection and spread of avian influenza in mammals was probably due to mammals eating infected dead birds and living in colonies in close contact with other animals.
Walruses, which can weigh up to two tons, feed mainly on fish and shellfish, but sometimes also on seabirds.
According to the US authorities, a polar bear has already died of bird flu in Alaska. It is suspected that the polar bear ate the carcasses of infected birds. Overall, the HPAI H5N1 virus has been threatening global bird populations for several years and has now also crossed the border into mammals. But not all species are affected to the same extent. Some species only act as carriers of the virus, while other species contract the disease very quickly, leading to increased mortality, especially among young birds and animals.
Heiner Kubny, PolarJournal
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