Borna disease virus 1 (BoDV-1)
For a long time, BoDV-1 has been noted to cause animal BD, a non-purulent meningomyelo-encephalitis of mainly horses and sheep in endemic regions of Germany, Liechtenstein, Switzerland and Austria. BoDV-1 is harbored by at least the insectivorous bicolored white-toothed shrew (Crocidura leucodon) as a natural reservoir. The shrews are asymptomatic and shed the virus by feces and urine. In 2018, the severe pathogenic potential of BoDV-1 for humans became apparent in a cluster of transplant-related BoDV-1 encephalitis cases in Germany with two fatalities; simultaneously, one sporadic unrelated fatal case was detected. Since then, more than 50 sporadic cases, some acute and some retrospectively diagnosed, have been published and/or were notified to public health authorities. It is suspected that most patients become infected close to their rural places of residence.
Variegated squirrel bornavirus 1 (VSBV-1)
VSBV-1 was detected in 2015 as the cause of fatal encephalitis in three private breeders of exotic variegated squirrels (Sciurus variegatoides) in the East of Germany. In 2018 and 2021, VSBV-1 was found to be responsible for the fatal encephalitis of two zoo animal caretakers in the North of Germany who had cared for another exotic squirrel species, Prevost’s squirrels (Callosciurus prevostii). Investigations in private holdings and zoological gardens in Germany and elsewhere in Europe revealed VSBV-1 detection rates of 1.5% - 8.5% in captive exotic squirrels. The animals are asymptomatic and show high viral loads in the brain, kidneys, urinary bladder, skin, and oral cavity, thus qualifying them as potential natural reservoirs. The origin of the virus and its route of introduction into the captive squirrel populations in Europe remained to be elucidated.