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2499 pages added, reviewed or updated during the last month (last updated: 18/4/2021)


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Japanese B encephalitis

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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:

Last reviewed 01/2018

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