ABSTRACT
Although most NiV-infected human patients presented with acute encephalitis, approximately 25% of cases also exhibited respiratory signs, and infection could also present as nonencephalitic or asymptomatic with seroconversion (10). Infection with NiV can also take a more chronic course with neurological disease occurring later (>10 weeks) following a nonencephalitic or asymptomatic infection. The recurrence of neurological disease (relapsed encephalitis) was also observed in patients who previously recovered from acute encephalitis. Relapsed encephalitis presented from several months to as late as two years after the initial infection, and two cases of relapsed encephalitis were observed in 2003, four years after infection (22-24). The underlying mechanisms that allow these viruses to escape immunological clearance for such an extended period are completely unknown and uniquely fascinating (1).
