Lassa fever encephalopathy: Lassa virus in cerebrospinal fluid but not in serum

The pathogenesis of neurologic complications of Lassa fever is poorly under stood. A Nigerian patient had fever, disorientation, seizures, and blood-br ain barrier dysfunction, and Lassa virus was found in cerebrospinal fluid ( CSF) but not in serum. The concentration of Lassa virus RNA in CSF correspo nded to 1 x 10(3) pfu/mL, as determined by a quantitative real-time polymer ase chain reaction assay. To characterize the Lassa virus in CSF, the 3.5-k b S RNA was sequenced. In the S RNA coding sequences, the CSF strain differ ed between 20% and 24.6% from all known prototype strains. These data sugge st that Lassa virus or specific Lassa virus strains can persist in the cent ral nervous system and thus contribute to neuropathogenesis. Lassa virus in fection should be considered in West African patients or in travelers retur ning from this area who present only with fever and neurologic signs.