A new study recently published by researchers at the Zoonotic Bornavirus Consortium (ZooBoCo) theorized that, in the wake of eight new Borna disease virus linked deaths, the disease may have been operating unnoticed for decades behind the scenes.
Borna is a virus that leaps from shrews to humans, causing encephalitis along the way. Symptoms tend to start with fever, headaches, and confusion, but progress into brain disease. In the latest cases, by the time they were admitted to the hospital, their symptoms deteriorated rapidly. There is no proven treatment for the disease, but there are tests for it.
Now, after tracking 56 patients who had developed encephalitis over the past 20 years, the researchers involved in this study believe that Borna could be responsible for several cases of encephalitis over the years, both severe and mild. However, they were not able to establish an exact route of transmission to humans. Their study was published in the journal Lancet Infectious Diseases.
“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,” Martin Beer, a professor at the Friedrich-Loeffler-Institut in Germany, said. “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.”
Researchers have proposed that clinicians test more often for Borna, going so far as to suggest testing for it in all patients affected by rapidly evolving central or peripheral nervous system disorders of unknown origins. Those patients could, they say, have come into contact with an infected, bicolored white-toothed shrew. The shrew typically appears in regions of central Europe.
The newly identified patients were all from southern Germany, and all died between 1999 and 2019. Every patient died within 16 to 57 days of admission to a hospital. Their recent diagnosis came from an analysis of their brain tissue. No surviving patients were diagnosed with Borna.
“Our findings indicate that Borna disease virus infection has to be considered a severe and potentially lethal human disease transmitted from a wildlife reservoir,” Barbara Schmidt, a professor from Regensburg University Hospital in Germany, said. “However, 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.”