Return of a bogeyman

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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Polio has lost its horror almost everywhere in the world. In Germany, too, it is considered to be eradicated. But now a new, highly aggressive virus variant is worrying the experts.

In 2010 a polio epidemic flared up in the Congo. At least 445 people became ill, most of them young adults. The virus turned out to be unusually aggressive: Almost half of the patients died - usually a maximum of five to ten percent. Even more puzzling, however, was that many infected people had been vaccinated against polio - and still became seriously ill.

Transformed pathogen

Almost four years later it is now clear why: The pathogen that carried away the Congolese is a mutation. Changes in the genome not only make it more dangerous, they also ensure that the common vaccination fails. "We have shown for the first time that the poliovirus is more versatile than previously thought," says Prof. Christian Drosten from the University of Bonn in an interview with . While other viruses, such as influenza pathogens, are constantly changing, the polio virus has so far been considered to be extremely stable.

Together with colleagues from Gabon, the researcher and his team isolated the Congolese virus from the deceased and let it loose on blood samples from 34 medical students at the University of Bonn. All of them had been vaccinated against polio in their childhood and had refreshed the vaccination as part of their studies.

Sick despite vaccination

With common polio viruses, the antibodies in the blood of the test persons were then able to cope with problem-free. The situation was different with the mutated virus: Here the immune reaction was significantly weaker. "We estimate that one in five of our test subjects could have been infected by the new polio virus, perhaps even one in three," says Drosten.

In our globalized world, pathogens can spread quickly across national borders - this also applies to polio. "For example, a few years ago infected pilgrims from Mecca infected others - and suddenly the disease broke out again in Indonesia," reports the scientist. Because polio is highly contagious: "In an unvaccinated population in which the disease is rampant, almost every child becomes infected before the age of two," says the virologist.

Extinction on the brink

The doctor is particularly concerned that the newly discovered variant is not the only one: "In that case, it will be very difficult, if not impossible, to eradicate polio as planned." The model is the eradication of smallpox - thanks to a consistent vaccination strategy, the world has been smallpox-free since 1980.

Theoretically, this would also be possible with polio: like the smallpox pathogen, the polio virus can only be passed on from person to person. In contrast to Ebola, for example, there are no pathogen reservoirs in animals from which the disease could repeatedly spread to humans.

And similar to smallpox, the polio vaccines offer excellent protection. However, this does not apply if the virus changes. Although it is not completely ineffective even with changed pathogens - as the example in the Congo shows, it can lose a large part of its effectiveness.

Questionable vaccine picking

The situation becomes particularly delicate if the population is not sufficiently vaccinated. This is also the case in Germany. According to the Robert Koch Institute, only 85 percent of the people here are vaccinated. The disease can be brought in again at any time, by travelers or - right now - by refugees from countries like Syria, where the virus is still raging.

"Especially when a modified pathogen hits a population that has not been vaccinated consistently enough, it becomes dangerous," warns Dorsten. He hopes that the discovery of the highly aggressive variant of the virus will be a wake-up call for widespread vaccination. The virus expert says: "Polio doesn't exist anymore" - that's just not true. "

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