Japanese encephalitis (JE) is a mosquito-borne (Culex tritaeniorhynchus) infection caused by a single-serotype RNA flavivirus (1).
The infection risk to travellers is 1:5000/month if living more than a month in rural areas during the season
It rarely (1 in 300 cases) proceeds to encephalitis but tends to be more serious in non-immune older patients. It is a greatly-feared disease, fatal in 25% of cases and causing parkinsonism, paralysis and retardation in 30-70% of survivors. It also causes abortion and fetal death.
Japanese and other children are routinely immunised.
Last reviewed 01/2018