JE is a viral disease associated with the high mortality (20 - 40 %). It is predominantly a disease of rural and peri-urban areas effecting mainly people (mainly children in   age group 2-15 yrs)  from low socio economic status.

In endemic areas, children between ages 2 & 15 primarily affected. In non endemic areas all the age groups are affected, children & older adults being the predominant victims.