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All animals are culled: avian influenza on a farm in the Czech Republic
Photo: Lubos Pavlicek / CTK Photo / imago images
SPIEGEL:
Mr. Mettenleiter, the first cases of the H5N8 bird flu virus in humans became known in Russia over the weekend.
The current corona outbreak could also have its origin in an animal.
Are we close to the next pandemic?
Thomas Mettenleiter:
At the moment I don't see that based on this initial verification.
We should take the situation seriously, but neither should we overestimate it.
It has been known since 1997 that bird flu viruses, also known as avian influenza viruses or avian influenza A viruses, basically have the ability to infect humans.
At that time, the H5N1 pathogen from this group spread to poultry in Asia, and there were isolated infections in humans.
So far, however, none of these bird flu viruses has managed to jump efficiently from person to person in the long term.
I therefore do not rate these first human cases of H5N8 infections in Russia as particularly worrying.
SPIEGEL:
Seven workers in a poultry fattening operation were affected.
Don't you really worry?
Mettenleiter:
We have been pointing out for years that all avian influenza viruses are potentially zoonotic pathogens, so they are basically able to infect humans.
Anyone who works with poultry must therefore take protective measures - dead poultry should not be touched with bare hands, and animals that have been proven to be infected should only be recovered in protective clothing and with respiratory protection.
The events in Russia will not change that.
The European Center for Disease Prevention and Control (ECDC) also stated on Wednesday that it regards the risk situation as very low for the general public and as low for people who work with poultry.
"These are highly changeable pathogens that can change much faster than coronaviruses."
SPIEGEL:
There is currently a lot of discussion about mutants in connection with the Sars-CoV-2 coronavirus.
How realistic is it that bird plague pathogens change in such a way that they can still be easily transmitted from person to person?
Mettenleiter:
We have also had this discussion since 1997. At that time, there was great fear that H5N1 could not only be highly contagious for poultry, but also cause humans and the next pandemic.
More than 50 percent of the people proven to be infected with H5N1 died from the pathogen.
But the fears have not been confirmed.
The pathogen could not establish itself in humans.
Instead, we had a swine flu pandemic with H1N1 in 2009.
For me, this shows that you have to be prepared for anything with influenza viruses.
These are highly changeable pathogens that can change much faster than coronaviruses and are therefore able to adapt quickly.
Nevertheless, they have not yet succeeded in specializing in the spread in humans.
more on the subject
Russia: People infected with the H5N8 bird flu virus for the first time
Dangerous animal disease: bird flu is spreading in Germany
SPIEGEL:
How dangerous is the H5N8 pathogen for humans?
Mettenleiter:
According to reports from Russia, the infections there were either asymptomatic, i.e. without any clinical symptoms, or those affected only had very mild courses.
We know that from transmissions with other bird flu viruses.
Typical signs in humans are temporary conjunctivitis or the appearance of flu-like symptoms.
We therefore always point out that people who develop corresponding complaints after contact with infected poultry should report to the health department.
But there are always isolated cases with a difficult course.
SPIEGEL:
Do you have an example?
Mettenleiter:
In a major H7N7 outbreak in the Netherlands in 2003, more than 80 people were known to have been infected with the bird flu virus.
The infection was mild in almost all of them, but a veterinarian died from it.
So you should take it seriously.
With the exception of H5N1 from 1997, we usually observe mild clinical courses, which is also in line with the current reports from Russia.
"That means we have a serious incident here in Germany that has to be taken very seriously."
SPIEGEL:
The terms avian flu and avian influenza already indicate that the pathogens primarily cause problems for poultry.
How dangerous are they for the animals?
Mettenleiter:
The H5N8 pathogen was first carried to Germany by migratory birds from Central Asia in 2014.
In 2016/2017, the most extensive series of outbreaks to date took place in Germany.
At that time, more than a hundred herds in poultry farming or in zoos were affected by infections.
Many animals had to be culled in order to contain the further spread.
In 2021 we have so far almost seven hundred wild birds tested positive and over 60 poultry holdings affected.
In addition, at the end of 2020 there was a mass death of wild birds on the North Sea coast in Schleswig-Holstein, which fortunately has now subsided again.
However, this shows very clearly how dangerous these pathogens are to wild birds and farm poultry.
SPIEGEL:
What exactly happened at the end of 2020?
Mettenleiter:
In November and December, more than 16,000 dead wild birds were found on the Schleswig-Holstein North Sea coast.
Although not all of these were tested for H5N8 due to the large number, we assume on the basis of extensive random samples that the vast majority of these animals died of bird flu.
In other words, we have a serious incident here in Germany that has to be taken very seriously.
Based on the samples that we received for closer examination, we can say that there are cases throughout Germany.
This is not good news for poultry farmers.
SPIEGEL:
Why is H5N8 so dangerous for birds while it apparently hardly weakens humans?
Mettenleiter:
You have to differentiate a little.
There are also wild birds, for example mallards, which become infected but do not become ill.
We know this from the examination of birds that were hunted healthy, which then test positive for the pathogen.
Insensitive, migrating species probably only bring the virus to us from reservoirs in Central Asia.
In your body, the virus only spreads through parts of the respiratory tract and digestive tract.
In the very susceptible species such as turkeys or chickens, on the other hand, it causes multiple organ failure and they die quickly.
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