Japanese Encephalitis

Transmitted by Culex mosquitoes, which breed in rice paddies and stagnant water. Mainly bite from dusk to dawn.

Symptoms

Most infections are asymptomatic. Symptomatic cases: fever, headache, vomiting, confusion, seizures, encephalitis. 20–30% fatality rate in encephalitis cases.

Treatment

No specific antiviral. Supportive intensive care for encephalitis (seizure management, airway protection, ICP management).

Endemic regions

East/Southeast Asia and the Western Pacific, especially rural agricultural areas. Seasonal (monsoon/post-monsoon).

Prevention & prophylaxis

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Ixiaro (inactivated vaccine)

2-dose series on days 0 and 28, completed ≥1 week before travel. Booster at 1 year if continued exposure. Approved for adults and children ≥2 months. Recommended for stays ≥1 month in rural endemic areas, especially during monsoon/post-monsoon season.

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Evening and nighttime mosquito avoidance

Culex mosquitoes bite primarily from dusk to dawn. Use DEET repellent in the evening. Sleep under bed nets, particularly in rural and agricultural areas near rice paddies or pig farms (amplifying hosts).