Northern Germany: avian influenza invades white-tailed eagles

For the first time, researchers have proven that influenza infection is endangered by the endangered birds of prey

White-tailed eagles are among the endangered species in Germany. Now some of them have died of bird flu. © Ekaterina Vasyagina / CC-by-sa 4.0
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Bird flu now also affects white-tailed eagles - a type of raptor threatened in Germany. Researchers have found 17 white-tailed eagles in Northern Germany who were infected with an aggressive strain of the bird flu virus H5N8. These are the first known cases of avian flu infection in these birds of prey and their protection poses new challenges. 14 of the 17 predominantly young animals had died from the infection, as the researchers report.

For years there have been bird flu epidemics in wild birds and domestic poultry. In 2007, thousands of birds had to be killed because of H5N1 virus infestation. In 2014, the H7N9 virus spread in China and was also transmitted to humans. The beginning of 29014 influenza type H5N8, which has appeared in Korea, has also been rampant in Europe since 2016.

17 infected sea eagles identified

Now it turns out that H5N8 can not only infect waterfowl and chickens, but also raptors like the white-tailed eagle. These were discovered by Oliver Krone from the Leibniz Institute for Zoo and Wildlife Research and his colleagues when they examined more closely an accumulation of hitherto mysterious deaths among white-tailed eagles (Haliaeetus albicilla) in the winter of 2016/2017. Of the endangered bird of prey, there are still around 750 breeding pairs in Germany, most of them in northern Germany.

14 dead white-tailed eagles and three obvious diseased animals had been found in Mecklenburg-Vorpommern, Schleswig-Holstein, Lower Saxony and Hamburg. A virological analysis has now revealed that these birds of prey were infected with a particularly aggressive strain of avian influenza H5N8. The virus can cause lethal brain inflammation in the animals, the researchers report.

A sea eagle infected with the H5N8 virus. © Oliver Krone / Leibniz-IZW

Particularly aggressive virus strain

The now proven H5N8 infections are the first bird flu cases in sea eagles. Against other Influenzavarianten these Greifv gel had previously proven to be immune. "It could be that the differences between viral strains are crucial. The virus strain 2.3.4.4b seems to be much more aggressive for many species of birds than previous stems, which is why it may have hit the big white-tailed eagle now, "explains Franz Conraths from the Friedrich Loeffler Institute. display

The white-tailed eagles are most likely to become infected with their food: "Sea eagles feed on carrion and, if available, on waterfowl, especially in winter, " says Krone. "Of course, sick and weak animals are easy prey for the white-tailed eagle. As a result, these birds of prey repeatedly expose themselves to viruses and other pathogens. "

Before all young animals affected

It is still unclear whether H5N8 infections are invariably fatal to sea eagles or whether the animals can survive the disease possibly if the strains are not so aggressive. "The observation that the majority of the 17 animals are young may also indicate immunization, " says Krone. "If these animals survive the infection, they may be susceptible to further infections."

According to the researchers, young white-tailed eagle may be particularly susceptible to infection with bird flu and may be more severely ill. Older animals, on the other hand, may already have developed some immunity to influenza viruses. "That could make her more resistant to emerging crowds, " hopes Krone. Although the existence of white-tailed eagles in Germany has been slowly recovering since the 1980s, the birds of prey are still regarded as threatened.

No danger to humans

For us humans, there still seems to be no cause for concern. In contrast to the virus variant H5N1, H5N8 has so far only been found in birds. "So far, H5N8 has not been known to transmit from animals to humans, " according to scientists at the Friedrich-Loeffler-Institut.

(Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, 05.10.2018 - NPO)