The virulence of genotype I (GI) Japanese encephalitis virus (JEV) is under debate. We investigated differences in the virulence of GI and GIII JEV by calculating asymptomatic ratios based on serologic studies during GI- and GIII-JEV endemic periods. The results suggested equal virulence of GI and GIII JEV among humans.
Keywords: Asia; GI JEV; GIII JEV; Japanese encephalitis virus; Taiwan; Western Pacific; asymptomatic ratio; flavivirus; genotype; meningitis/encephalitis; mosquitoborne; vector-borne infections; virulence; viruses.