Human Vilyuisk encephalitis.

For more than a century, a type of human encephalomyelitis has been known to affect indigenous people in the Sakha Republic in the Vilyui River Valley in Russia. The clinical features, laboratory findings, neuropathology, epidemiology and search for a causative pathogen are reviewed. One of the agents (Vilyuisk human encephalitis virus; VHEV) implicated in Vilyuisk encephalitis, belongs to a separate clade of Theiler's murine encephalomyelitis virus (TMEV). The recent discovery of theiloviruses from humans and the complete sequence of the VHEV raise the possibility that Vilyuisk arose from human cases of Vilyuisk encephalitis as a human-TMEV recombinant virus. Copyright (c) 2008 John Wiley & Sons, Ltd.