Berlin.
The bird flu virus has apparently spread from mink to mink. Has this increased the risk to humans? experts warn.
It is the most severe outbreak of the bird fluthat Europe has ever seen. For months, the virus has been spreading among farm, zoo and wild birds, millions of animals have already died or have been slaughtered, tens of thousands in Germany. The extent of the outbreak and an observation on a mink farm in Spain worry experts: is the virus changing in such a way that it will also be transmitted from person to person in the future?
Avian flu: what kind of virus is it?
Influenza viruses circulate worldwide not only in humans, but also in animals – according to the Robert Koch Institute (RKI) especially in birds (avian influenza), pigs (porcine influenza) and horses. There are many different subtypes, denoted by H and N and the numbers one to sixteen. The letters stand for the most important ones proteins on the envelope of the flu virus: hemagglutinin and neuraminidase.
According to the RKI, avian influenza viruses are divided into low pathogenic viruses, i.e. those that cause little disease, and high pathogenic viruses that cause severe diseases. Highly pathogenic influenza A viruses can cause serious illnesses in livestock and wild animals damage in flocks because a large proportion of infected birds die from the disease. Bird flu is also sometimes referred to as avian influenza.
Avian influenza: What is special about the current outbreak?
In the past, there have always been outbreaks of bird flu worldwide in winter. These ebbed in spring or Summer mostly at least in the area. “This time, however, there was a virus type or several virus subtypes that even increased in the summer,” says biologist Wolfgang Fiedler, research associate at the Max Planck Institute for Ornithology.
In addition, according to Fiedler, seabirds were also affected, in which such an outbreak in Central Europe has not yet been proven. “Projections indicate that a five-digit number of wild birds have died in Germany. Just the number of dead animals that were collected was frighteningly high,” he says.
Have humans contracted bird flu?
Avian influenza A viruses can also make people sick. The transmission According to the RKI, from animals to humans has not been very effective so far. This means that the viruses are usually not very infectious for humans. However, if an infection occurs, the disease can also be severe and fatal.
According to the World Health Organization (WHO), there have been around 900 cases of highly pathogenic avian influenza A viruses since the late 1990s Type H5N1 in people. More than half of those infected died. Other subtypes are occasionally detected in humans. According to the RKI, there has not yet been a case in Germany.
According to the information, experiences with bird flu viruses have shown that so far mainly people with close contact to infected farm poultry are at risk. The risk of infection is currently generally described as low.
Why are some experts concerned?
The danger has been described for years: whether a certain avian influenza virus really genetically can change and adapt to humans in such a way that it can be transmitted from person to person cannot be predicted, according to the RKI. However, some experts are currently particularly concerned.
This is not only due to the current extreme spread of the virus, but also because it is in Spain in a mink farm possibly spread from mammal to mammal. “This urgently needs to be investigated further,” said Thomas Mettenleiter, virologist and President of the Friedrich Loeffler Institute, the Federal Research Institute for Animal Health, the “Spiegel”.
Much is still uncertain, but the outbreak in the mink farm could be the first expression of one Adjustment of the virus to mammals. “That would be a new quality in terms of possible spread.” Further mutations at suitable sites could also open the way for the virus to humans.
“These viruses are like ticking time bombs,” explains Ian Barr, deputy director of the WHO influenza center at the Doherty Institute in Melbourne (Australia) in an interview with the international vaccine alliance Gavi. “Occasional infections are not a problem – the real crux of the matter is the gradual increase in new ones Characteristics. With so many viruses out there mutating in so many different ways, you can’t be 100 percent sure something bad won’t happen,” Barr said.
According to the immunologist, a number of changes would have to happen and the virus would also probably have to be passed between people for a while in order for a real one to develop transferability build up. “So it’s not just a snap of the fingers. It may take years or decades, or it will never happen. But I don’t think we can be so blase as to just ignore these things,” Barr said.
How well are the authorities prepared?
Influenza viruses have also passed from pigs to humans. A swine flu virus has even triggered a pandemic – 2009/2010. The authorities are correspondingly attentive. “Every case of human influenza infection with a previously unknown virus is followed up to identify the virus and its origin,” says Mettenleiter. In his opinion, however, it would be desirable to better monitor the development of influenza viruses in mammals and to continuously characterize the pathogens involved.
Avian influenza: are there vaccines for birds?
“The vaccination of birds has been discussed for years,” says Wolfgang Fiedler. A corresponding vaccine is available. However, many countries reject large-scale vaccination campaigns, including Germany. “One plausible argument put forward by opponents is that vaccination can risk It is growing enormously that you have farm animals in your stock that are shedding the virus but are not recognized”. That would fuel the plague. The poultry industry has legitimate concerns. In the wild, a corresponding vaccination campaign for animals would not even be possible.
Is there a vaccine for humans?
In Germany, several vaccines are approved for humans. An inactivated vaccine has recently been on the market. Two doses of vaccine three weeks apart are required for protection. One is recommended immunization only in special cases. Especially when people have professional contact with live poultry.
How high the protection is is controversial. “Traditionally, vaccines against avian influenza don’t solve really good and strong ones in humans immune reactions out,” says influenza expert Barr. The new mRNA technology, which led to the rapid development of a vaccine against corona, has not yet been tried here. “We know they work to an extent, but how well they work and what protection they would provide is an open question,” Barr said.
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