The rare Borna virus has been detected in a person in Bavaria. Animals transmit it and the disease is usually fatal. FOCUS Online explains what you should know about the pathogen and how to protect yourself.
A very rare infection with the Borna virus has been detected in Bavaria. As the district office announced on Tuesday, a person from the Mühldorf am Inn district was affected. There is no further information so far. The disease, which is usually fatal, only occurs in a few isolated cases in humans in Germany.
Two more Borna virus infections had become known in the district in the past three years. The so-called classic Borna virus triggers a brain inflammation that ends fatally in almost all cases. Those who survive usually retain the most severe consequential damage. On average, two infections are reported in Germany every year. However, scientists assume that the number of unreported cases is higher – up to six cases per year, which is still very rare.
But what is behind the deadly pathogen? And how is it transmitted? An overview.
The Borna virus is also known under the names Borna Disease Virus 1 (BoDV-1), “classical Borna” and “Pferdeborna” and has been considered an animal disease for more than 250 years. In 2018, BoDV-1 was first identified as the cause of severe encephalitis in humans.
So far, the pathogen has not been sufficiently investigated. In order to find out more about Borna’s disease in humans, two research groups on the pathogen, Bornavirus Focal Point Bayern and ZooBoCo, have been founded over the past five years. Among other things, they research transmission routes, risk factors, virus carriers and possible further forms of an infection.
BoDV-1 is clearly distinguishable from the so-called spotted squirrel Bornavirus. The virus can also be transmitted to humans and can cause severe inflammation of the meninges.
The field shrew is the only known reservoir of the virus so far. The pathogen of infected animals is usually excreted via the saliva, urine or faeces. Scientists are currently assuming that horses and sheep come into contact with the shrew and their excrement when eating, for example.
The mouse does not necessarily have to be touched. Borna viruses can, for example, be ingested through food or water contaminated with excrement and transmitted to humans. In addition, bite injuries and inhaling contaminated dust can transmit the pathogen to humans. It is conceivable that other animals such as domestic cats that hunt mice represent a link in the transmission chain, reports the Robert Koch Institute (RKI). It is currently being investigated whether other closely related shrew species such as the garden shrew can transmit the virus.
So far, the scientists consider transmission from person to person to be unlikely.
The field shrew, as the host of the pathogen, is mainly found in central and south-eastern Europe. In Germany, too, it occurs increasingly in the eastern half of Germany, especially in Bavaria, Thuringia and Saxony-Anhalt. In addition, the virus was detected in animals in Switzerland, Liechtenstein and Austria.
According to the RKI, the following symptoms are known so far:
So far, all known cases have been fatal with just one exception. There is currently no specific therapy against infection with the pathogen.
Only a few cases of the disease in humans are currently known. According to the Bavarian State Office for Health and Food Safety, the number of infections has been in the mid double-digit range since 1996. In 2021, seven infections had become known across Germany, five of them in Bavaria. Individual cases were also recorded in Brandenburg, Saxony-Anhalt, Thuringia and North Rhine-Westphalia.
Since March 1, 2020 there has been an obligation to report Borna virus infections. Accordingly, the direct virus detection of Borna viruses in humans must be reported to the health department for laboratories.
Currently, infections with the Borna virus are very rare. The risk of infection is correspondingly low. So far, there is no vaccine against the pathogen available.
In order to protect yourself nevertheless, the RKI has summarized the following precautionary measures:
