Virtually no one thinks of squirrels as anything more than cute spastic creatures that are fun to watch. All animals harbor dangerous infectious disease that--in specific contexts--can pose a risk to humans. Accordingly, it has been well-established that squirrels are connected, via their lice, mites, and fleas, with plague, certain forms of typhus, and rickettsialpox (for example).
A newly discovered virus (likely directly transmitted from squirrels) can now be added to these indirectly transmitted infections: variegated squirrel 1 bornavirus (VSBV-1).
What is interesting about this newly discovered fatal encephalitis-causing virus is that it appeared in 3 German squirrel breeders and how it was identified.
Anyone who operates at the interface of humans and animals should be considered a sentinel or a canary in the coal mine for novel infections. Most human infections originated from animals and jumped into the human species at some point, so it is likely that animals will remain a major source of new infections. Such a fact underscores how important it is to be extremely vigilant when dealing with an unexplained illness in individuals who have unusual animal exposures and never being satisfied until an actual etiology has been established--something that happens all to rarely.
Additionally, the identification of this virus employed a metagenomic approach in which sequencing of nucleic acid was performed directly on squirrel samples with the aim of finding genetic material that could be linked a known microbe family.
The paper is, to me, significant not just for the description of VSBV-1 but for highlighting the importance of viral discovery and the principles that should be applied.