Borna virus outbreak in Bavaria: Two children die – expert explains what we know
Created: 08/17/2022, 04:56
By: Carina Zimniok
Voluntary blood collection: A study on the Borna virus is underway in Maitenbeth.
Citizens' blood is tested for antibodies.
© Richterstetter
Two top researchers report to the Munich Merkur what is known about the infection and symptoms of the Borna virus.
We answer the most important questions.
Maitenbeth – Two children from the small town of Maitenbeth (Mühldorf district) died of the Borna virus.
2019 a girl, beginning of August a seven-year-old boy.
Almost 40 Borna cases were detected across Germany.
But in Maitenbeth and the surrounding area, the cases are increasing.
The virus is not new; Borna's disease in animals has been known for over 100 years.
It is named after the town of Borna in Saxony.
There used to be a large cavalry there and many horses died of brain disease.
Science is still in its infancy when it comes to researching the virus.
A large research group has been working on this since 2015.
Among others, Professor Martin Beer, head of virus diagnostics at the Friedrich Loeffler Institute near Greifswald, and Professor Dennis Tappe from the Bernhard Nocht Institute for Tropical Medicine in Hamburg.
Tappe says: "I have rarely researched anything more interesting." The two experts explain what is known about Borna so far - and what insights they hope to gain from the study.
Who is infected with the Borna virus?
There are almost 40 Borna cases in Germany, and in some cases the virus was only detected after death.
In order to unmask previously undiscovered cases, there is cooperation with clinics and institutes nationwide: cases of severe encephalitis are in demand.
Blood samples were frozen for unexplained deaths.
"The virus cannot be detected in the blood, but the antibodies against it can," explains Beer.
The number of unreported cases is probably higher.
But it is getting smaller because more and more clinics are examining the Borna virus.
The Maitenbeth cases fuel the suspicion that children are more vulnerable than adults.
"But that could very well be a coincidence," says Dennis Tappe.
But it is also possible that children and seniors, who are more frequently affected, do more things that others do not do: play outside or work in the garden.
An ongoing study and previous data show: "Extremely rural areas are particularly affected," says Tappe.
Small villages.
And if it's a larger place, the cases almost always occurred on the outskirts of the village.
Two children from the small town of Maitenbeth (Mühldorf district) died of the Borna virus.
2019 a girl, beginning of August a seven-year-old boy.
© FKN
How is the Borna virus transmitted?
Researchers are still puzzled about this question.
In 2011 and 2013 there were three cases of dead squirrel breeders.
In 2015, a new Bornavirus was described.
"That was the first evidence of a deadly infection in humans." Many of the squirrels, which are no longer native here, have been examined so far, explains Beer.
"We haven't found any positive squirrels for more than two years." The shrew is suspected of the current cases, especially the American shrew.
The diseases occurred in their distribution areas.
The virus was only detected worldwide in Germany, Austria, Switzerland and Liechtenstein.
Human infections are only known in Germany.
Bavaria is a core area here, says Beer.
However, it is unclear how one actually becomes infected.
Through bites?
Contact?
feces?
In the known cases, according to Tappe, none of the relatives can remember that a patient had had contact with a shrew.
"We know that shrews excrete the virus via urine and saliva and do not get sick themselves," explains Beer.
"As far as we know, she is the only animal that passes on the virus." Other animals such as horses and sheep, but also humans are considered dead-end hosts.
"They don't pass on the virus, but they do get sick - and usually severely."
What is the course of an illness with the Borna virus?
The mysterious virus scares many people, especially in the affected region.
Professor Tappe says very clearly: "As far as we know, the disease is 100 percent fatal." But he also emphasizes: "Borna encephalitis is an extremely rare disease.
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It begins with non-specific symptoms, explains Beer.
fever, malaise, headache.
"The incubation period lasts weeks to months." When those affected go to the doctor, they usually already have severe symptoms.
The last phase is a comatose state.
"The virus does not destroy the brain - but it settles in the brain," explains Beer.
Ultimately, the patients die from their own immune defenses against the virus.
"The body fights its own brain."
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Are there any medicines against the Borna virus?
According to Tappe, there are drugs that have been shown to be effective against Borna viruses in cell cultures.
"But someone has to think about Borna early on," says the scientist.
Patients first end up with their family doctor, then with a neurologist, and eventually in the university hospital.
“Then the patients are sick for two or three weeks.
Every miracle pill comes too late.” The doctors used antiviral drugs in the patients who were diagnosed with the virus in the clinics, explains Beer.
Immunosuppression was also used.
For example with the seven-year-old from Maitenbeth.
But the medication didn't help.
What insights should the study provide about the Borna virus?
The result of the large-scale investigation of Maitenbether is to be published in autumn.
If no Borna hits appear there, that's good news for the residents, emphasizes Tappe: "It means that the virus is not spread everywhere.
We've drawn blood from people before.
You find very little, if anything.”
The Friedrich Loeffler Institute is studying the shrews in the region.
However, this is complicated, explains Beer.
Because the species is protected.
"You need a lot of permits." The researchers benefit above all from dead shrews that are found and sent in under appropriate security measures.
Cats could also become infected in rare cases, but not pass the virus on, says Beer.
Nevertheless, he recommends that cats should not be petted or picked up immediately after they have brought a dead shrew.
According to Beer, it is not yet possible to say whether Maitenbeth is really a hotspot for the Borna virus or whether the cases there have increased by chance.
“Overall, there are fortunately only extremely few cases in the affected areas in Germany.
The risk of infection is extremely low.”
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