Regensburg (dpa) - A new study on the so-called classic Borna virus suggests that primarily people from very rural regions get sick with the rare infection.

That comes from a study presented on Tuesday by the Robert Koch Institute (RKI).

The doctor and epidemiologist Kirsten Pörtner asked the relatives of eight patients who died of the virus.

The result: everyone lived in the country, seven out of eight had a cat.

The only known reservoir host of the pathogen is the field shrew (Crocidura leucodon), in which the infection does not cause any symptoms.

The shrews excrete the virus in urine, feces and saliva - this can then infect other mammals and, in rare cases, humans.

"Cats may bring their owners into contact with shrews and the virus through their hunting behavior - the cats themselves were inconspicuous," says Pörtner.

Borna viruses cause encephalitis, which in almost all cases is fatal.

An average of two infections are known in Germany each year, but scientists assume that the number of unreported cases is higher, with up to six cases per year.

A focus of the infections is in Bavaria.

"We don't know why that is so," said Portner.

“It is possible that people in Bavaria are now looking more closely and are more likely to test for the virus in the case of encephalitis for an unknown cause.

But it is also possible that there are more shrews in Bavaria that are colonized with the virus. "


Both Bavaria and Saxony-Anhalt, along with other federal states, are among the areas in Germany where the classic Borna virus can occur.

Information from the Robert Koch Institute on the Borna virus

Medical journal on the Borna virus