Japanese B encephalitis
Last reviewed 01/2018
Japanese encephalitis (JE) is a mosquito-borne (Culex tritaeniorhynchus) infection caused by a single-serotype RNA flavivirus (1).
- tend to occur in wet areas (rice paddies and other open water sources) where Culex tritaeniorhynchus (and similar species) lay eggs
- pigs and aquatic birds are important as principal vertebrate amplifying hosts
- is not transmitted from person to person (2)
- humans rarely develops enough viremia to infect feeding mosquitoes (dead-end JE virus hosts)
- <1% of human JEV infections result in JE (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.
Reference:
Japanese encephalitis B vaccination