Japanese viral encephalitis mimicking stroke with an initial manifestation of hemiplegia

Japanese encephalitis (JE) is an endemic disease in Taiwan. After the program to vaccinate children against JE was implemented in 1968, the incidence of JE gradually started to decrease, but it is still an important infectious disease here. Neurological manifestations in JE vary highly during the initial stage of the disease. Focal neurological symptoms, such as hemiplegia, are rarely reported. A 46-year-old male with the initial presentation of abrupt hemiplegia and fever developed mental confusion after 1 day. No bacterial pathogen was isolated from the blood or cerebrospinal fluid (CSF). A diagnosis of JE was confirmed based on the presence of JE virus-specific immunoglobulin M in the CSF and serum samples. It is necessary to consider JE when a patient presents with abrupt hemiplegia with fever followed with mental confusion and seizure, especially if the patient comes from a JE-endemic area.