Researchers alarmed: avian flu hits more and more mammals Jennifer Coolidge (Stifler’s mother) was named “Woman of the Year”.

The largest bird flu ever documented is currently raging in almost all parts of the world. According to figures from the BBC, the current flu wave, which started in October 2021, has killed more than 208 million birds. The H5N1 virus is highly contagious and can cause serious damage to the internal organs of birds when infected. And that in a very short time: An outbreak of the virus can wipe out 90 percent or more of a bird population in 48 hours.

What worries researchers: more and more cases are also being discovered in mammals.

Bird flu kills animals on mink farms

When countless animals suddenly died on a fur farm in Galicia in October, an infection with the corona virus was initially thought. The thought was obvious: At the start of the corona pandemic in 2020, the virus spread like wildfire through mink farms worldwide. A major problem, because intensive livestock farming gives the virus the chance to mutate more quickly. To prevent this, millions of minks have been killed over the course of the pandemic.

However, the minks on the farm in Galicia were not sick of Corona, but of the bird flu virus H5N1, tests showed. In the end, the result was the same: 50,000 animals had to be killed. Alarm bells are ringing among experts.

“This is incredibly worrying”, virologist Tom Peacock of Imperial College London told Science magazine. He sees a clear mechanism for an avian flu pandemic to emerge. Multiple mutations have already been found in four animals. For example, one helps the H5N1 virus spread better in mammalian tissue.

What exactly that means is still unclear. The outbreak could also remain an isolated case, says Thomas Mettenleiter of the Federal Research Institute for Animal Health against the “Spiegel”. It is not known whether the virus has spread further from the mink herd and whether animal-to-animal transmission of this virus to other mammals is possible.

The fact that mammals can be infected with the bird flu virus is not new in itself: Canadian and US authorities have discovered the virus in a range of animal species from foxes to bears over the past year. These reports have multiplied in the past 18 months, Gregorio Torres, scientific director of the World Organization for Animal Health (WOAH), told the BBC.

This is either due to good surveillance – which in itself would be a good sign – or an indicator of a change in the virus.

Mysterious mass deaths of seals

Seals are also among the mammals affected by the bird flu virus. But seals, foxes, martens and other wild mammals do not infect each other the way minks do, but infect themselves through bird carcasses or the faeces of sick birds.

Seals in the Caspian Sea appear to have been particularly hard hit. The Russian State University in Dagestan reported that 700 dead seals had been discovered in early December. Tests had shown that the seals were infected with the bird flu virus. Whether the animals actually died from it has yet to be investigated. It’s possible: Last summer, wild birds on a nearby island were hit by the highly contagious type H5N1.

That is the situation in Switzerland

The virus is also on the rise in Switzerland. In Switzerland, five new cases have been added in the past two weeks.

This week, two new cases were discovered in wild birds in the canton of Zurich. Two cases have been reported in wild bird carcasses in Basel-Stadt in the last 14 days. And on Monday, the veterinary service of the canton of Lucerne announced that the highly contagious H5N1 virus had been discovered last week in a Mediterranean gull in Sursee.

Bird flu had already been detected in individual wild birds in December and January. Two swans tested positive in Ticino, a seagull each in the cantons of Thurgau, Lucerne, Zurich and Schaffhausen, a bird of prey in the canton of Zurich, and a gray heron and a wild bird in Basel. There were also cases in neighboring countries.

danger to humans

The risk of possible infection in humans is low, says Barbara Wieland, director of the Institute of Immunology and Virology, Friday morning in the program “Heute Morgen” on Swiss radio SRF. The known cases of the last two years are people who have had close contact with birds.

In total, only 868 cases of bird flu in humans were documented between 2003 and November 2022. However, according to the WHO, these were often fatal: 457 of the 868 infected people died, which corresponds to a mortality rate of 53 percent.

Nevertheless, the WHO issued the all-clear in its January risk assessment report. The virus does not have the ability to be permanently transmitted to humans. The chance of spreading from person to person is therefore small.

But no reason to sit back, the WHO emphasizes:

Daniel Olson, an epidemiologist at the University of Colorado, also warns the Vox news site:

The biggest threat at the moment is the rapid spread and the associated higher risk of mutation.

Switzerland does the opposite

On Thursday, the federal government extended the measures to protect against avian flu until at least March 15. According to the Federal Food Safety and Veterinary Office (BLV), their main purpose is to avoid contact between wild birds and domestic poultry. The measures have been in effect since November after the avian flu virus was detected at a company near Winterthur ZH.

According to the FSVO, the risk of introducing bird flu into Switzerland remains high until the wild waterfowl have left their winter home in Switzerland around the beginning of March. The federal government also recommends hygiene measures and limited access to the stable. Poultry markets and exhibitions are still prohibited. The measures apply to both poultry farms and hobby livestock farming.