A virus that can jump from shrews to humans could be to blame for previously unexplained deaths in Europe, scientists have found.
A study of brain tissue samples from more than 50 patients who died from encephalitis, or brain swelling, over 20 years has identified eight new cases of the Borna virus.
The research, published in the Lancet Infectious Diseases journal, suggests where the virus exists in the wild it could be the cause of unexplained encephalitis cases.
Shrews are a small mole-like mammal prevalent throughout Europe. The bicoloured white-toothed shrew is the main carrier of the virus and can be found in Germany, Austria, Switzerland, and Liechtenstein.
All the newly diagnosed patients died between 1999 and 2019 and lived in southern Germany but researchers say they cannot rule out if the virus is responsible for less severe infections.
They believe doctors should test for the Borna virus more often in patients who are struck down by a rapidly developing nervous system disorder that cannot be explained and where the patient may have come into contact with the mammals.
Symptoms in infected people start with a fever, headache and confusion, and continue with signs of brain disease such as an unsteady gait, memory loss, seizures, and a progressive loss of consciousness.
In the new cases, symptoms deteriorated rapidly following patients’ admission to hospital, leading to deep coma and death. All eight patients died within 16 to 57 days of admission.
Professor Martin Beer from Friedrich-Loeffler-Institut in Germany said: “Our tests bring the total number of reported cases of human Borna disease virus in southern Germany to at least 14, so it is still relatively rare in absolute numbers, but it might be behind a larger proportion of unexplained severe to fatal encephalitis cases.
“Only more tests on patients with severe or even deadly encephalitis will find this out, and earlier detection might be possible using serum and cerebrospinal fluid samples from living patients.”
Professor Barbara Schmidt from Regensburg University Hospital, Germany added: “It’s not a newly-emerging disease, but one that appears to have occurred unnoticed in humans for at least decades, and may have caused other unexplained cases of encephalitis in regions where the virus is endemic in the host shrew populations.”
