2023-11-12 09:16:00
Scientists around the world are working hard to prevent another pandemic from breaking out. One candidate is bird flu, which also kills mammals.
Von Nikta Vahid-Moghtada, MDR
While flu and corona numbers are rising in Germany, researchers around the world are trying to answer a completely different question in high-security laboratories: Which virus has the potential to trigger the next pandemic?
A hot candidate has been rampant almost all over the world for years: the bird flu virus H5N1. It circulates among bird populations worldwide. The numbers explode. Bird flu has become a pandemic in the animal kingdom, a so-called panzootic. But it doesn’t stop with millions of dead birds.
More and more mammals are affected
Mammals are now increasingly being affected. In New England in the northeast of the USA, for example, there has been a mass death of seals as a result of the bird flu that is currently circulating. Hundreds of harbor seals and gray seals have died from H5N1, a research team from Tufts University in Medford (USA) reported in the journal “Emerging Infectious Diseases” at the beginning of the year.
In South America, a continent that was spared from bird flu for a long time, a H5N1 subtype for mass extinction of seals and other marine life to be responsible. So far, only Australia and Antarctica have been spared.
It is not far from mammals to humans. The virus has also occasionally spread to people. In this case it is called a zoonosis. Between January 2003 and August 2023, 878 H5N1 infections in humans were reported to WHO worldwide. 458 of them were fatal. So it seems only a matter of time before the virus can be transmitted not only from animal to person, but also from person to person.
Zoonosis
Diseases that initially only affect animals and then spread to humans are so-called zoonoses. Most previous pandemics, such as the plague, smallpox or, most recently, SARS-CoV-II, were triggered by pathogens that spread from animals to humans – so-called zoonotic pathogens. The infectious diseases they cause are called zoonoses. The Spanish flu of 1918 was also such a zoonosis. According to current knowledge, bird flu viruses mixed with swine flu viruses and spread to humans.
Will bird flu pose a threat to humans?
Timm Harder, infectious disease doctor and laboratory manager at the Friedrich Löffler Institute in Greifswald, researches the bird flu virus and its subtypes. “We currently have a virus in circulation that is apparently very, very well adapted to the bird host. It spreads very quickly and is transmitted very well,” says Harder. And the further the virus spreads, the greater the chance that a virus particle will make the leap from the animal world to humans, according to the expert.
Flu viruses can adapt particularly well to their potential hosts. Even worse: Different flu viruses can also reassemble in a host and form a completely new virus. This ability is called “reassortment.” And that’s exactly why flu viruses pose an immense danger, say scientists like Sebastian Ulbert. “I consider the influenza viruses to be the most dangerous viruses that exist.”
Ulbert conducts research at the Fraunhofer Institute for Cell Therapy and Immunology in Leipzig. The zoonotic origin makes the viruses’ quick adaptability more difficult: “We have no control over how and where these viruses change,” says Ulbert.
Influenza
The influenza virus belongs to the RNA viruses, a group of viruses that can mutate particularly easily and quickly. Whenever the virus replicates itself in the cell, small copying errors occur. This creates new variants that differ from each other in small details. This is why influenza is particularly good at adapting to new conditions.
What is being done preventatively?
One person who starts at exactly this point is Fabian Leendertz. He is trying to find out which events and chains can actually lead to pandemics. Leendertz is founding director of the Helmholtz Institute for One Health (HIOH) and researches the ecology and emergence of zoonoses there. “Sars-CoV-II has shown us very clearly how such a zoonotic event can become a pandemic. We must now try to ensure that as few more of these pathogens as possible come our way,” says the scientist. His One Health approach takes a holistic approach and records data not only regarding the pathogen itself, but also regarding its host and its environment.
Leendertz makes it clear: As a rule, humans are responsible for the ecological and climatic changes that make zoonoses possible. “We come into contact with the animals, not the animals with us.”
Climate change as a catalyst for infectious diseases
Just one example of this: Flavi viruses, which cause diseases such as dengue fever, Zika fever, yellow fever or West Nile fever and are transmitted by mosquitoes or ticks. Transmitters are often insects, which are increasingly advancing into Western European habitats as a result of man-made climate change. Humans created the climatic conditions for the spread of disease vectors in the first place.
“Pandemic Preparedness” is the virus researchers’ credo – be prepared for the next pandemic. And that means: sharing knowledge in global collaboration, developing vaccines and active ingredients, and above all: observing dangerous viruses in order to be able to estimate whether and where they are breaking out.
The two-part documentary “What will be the next pandemic?” creates an overview of the research carried out by scientists around the world – from Bangladesh to Central Africa to Leipzig in Saxony. “What will be the next pandemic” is available from November 13th. available in the ARD media library.
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