Active Case Finding of Current Bornavirus Infections in Human Encephalitis Cases of Unknown Etiology, Germany, 2018–2020
Philip Eisermann, Dennis Rubbenstroth, Dániel Cadar, Corinna Thomé‐Bolduan, Petra Eggert, Alexander Schlaphof, Frank Leypoldt, Martin Stangel, Thorsten Fortwängler, Florian Hoffmann, Andreas Osterman, Sabine Zange, Hans-Helmut Niller, Klemens Angstwurm, Kirsten Pörtner, Christina Frank, Hendrik Wilking, Martin Beer, Jonas Schmidt‐Chanasit, Dennis Tappe
Abstract
Human bornavirus encephalitis is a severe and often fatal infection caused by variegated squirrel bornavirus 1 (VSBV-1) and Borna disease virus 1 (BoDV-1). We conducted a prospective study of bornavirus etiology of encephalitis cases in Germany during 2018-2020 by using a serologic testing scheme applied along proposed graded case definitions for VSBV-1, BoDV-1, and unspecified bornavirus encephalitis. Of 103 encephalitis cases of unknown etiology, 4 bornavirus infections were detected serologically. One chronic case was caused by VSBV-1 after occupational-related contact of a person with exotic squirrels, and 3 acute cases were caused by BoDV-1 in virus-endemic areas. All 4 case-patients died. Bornavirus etiology could be confirmed by molecular methods. Serologic testing for these cases was virus specific, discriminatory, and a practical diagnostic option for living patients if no brain tissue samples are available. This testing should be guided by clinical and epidemiologic suspicions, such as residence in virus-endemic areas and animal exposure.