A method for diagnosis of viral encephalitis comprises contacting first nucleic acid sample with the first PCR reagent including at least one primer pair selected from primer sequence set forth in SEQ ID No 1 and SEQ ID No 2, SEQ ID No 3 and SEQ ID No 4, or SEQ ID No 5 and SEQ ID No 6: and subjecting said first sample with the first PCR reagent to thermal cycling.