Japanese encephalitis virus

Background

• Single-stranded positive-sense enveloped virus in the family Flaviviridae and genus Flavivirus
• Found in Asian and the western Pacific
• Reservoir is pig and wading birds
• Vector-borne, transmitted by Culex species mosquitoes
• More common in children and non-immune adults
• Overall, extremely low risk for travellers with 66 cases in Western travellers since 1973 and estimated less than 1 case per 10 million trips

Clinical Manifestations

• Incubation period of 5 to 15 days
• 99% of infections are asymptomatic
• Syndrome is characterized by parkinsonism

Prognosis and Complications

• 20-30% mortality among people who develop encephalitis
• 30-50% of survivors have neuropsychiatric symptoms

Management

• Supportive

Prevention

• Vaccine is not routinely recommended due to the rarity of disease
• Vaccine may be considered if there will be rural exposure, repeated travel to risk areas, longer cumulative duration of travel (e.g., > 30 days), or travel in areas suffering an outbreak
  • However, disease is still rare