JEV-Specific IgM can be detected in CSF and or serum in approximately 75% of patients within 4-7 days after the onset of illness and nearly all patients are positive 7 days after onset. Commercial kits are now available(MAC ELISA) for detection of JE IgM using dot-blot or immunoprecipitation IgM assays. JEV can also be detected by analyzing the CSF through the RT-PCR technique.