Viliuisk encephalomyelitis in Eastern Siberia - analysis of 390 cases.

Viliuisk encephalomyelitis (VE) is a unique disease occurring in the Yakut (Sakha) population of Eastern Siberia. VE is always fatal, with some patients dying during the acute encephalitic phase of illness; those surviving the acute phase develop progressive dementia, rigidity and spastic quadriparesis as part of a more prolonged pan-encephalitic syndrome. The disease is characterized neuropathologically by multiple widespread micronecrotic foci with marked inflammatory reactions and subsequent gliosis throughout the cerebral cortex, basal ganglia, cerebellum and brain stem. The acute febrile onset with cerebrospinal fluid pleocytosis and increased protein and neuropathology showing inflammatory reactions suggest that VE is an infectious disease, but the causative agent has not been identified. Initially detected in a small mixed Yakut-Evenk population of the mid-Viliui region, the disease subsequently spread south to densely popu