Japanese Encephalitis is a viral infection caused by RNA viruses belonging to the Flavivirus genus. It is a zoonosis (an animal disease that can spread to humans) primarily transmitted by Culex mosquitoes that bite infected birds, pigs and other mammals passing the infection to humans living and working in rural areas around rice paddies and irrigation systems. Risk: Travellers to endemic areas are at risk, especially those visiting rural areas, farms, rice fields and irrigation areas, including persons involved in outdoor recreational activities or on working assignments. Children under 15 years of age seem to particularly susceptible to the infection. Outbreaks typically occur during or shortly after the rainy season in temperate regions and year-round, with peak transmission during summer months, in tropical regions. Japanese Encephalitis is endemic in Southeast Asia. Symptoms: The majority of cases are asymptomatic (persons do not exhibit symptoms). If a person exhibits symptoms, they usually appear between 5 to 15 days after being infected. They include fever, severe headache, vomiting, diarrhea, and general weakness. Some patients will develop neurological symptoms such as tremors, seizures (especially children), expressionless face, and sudden paralysis which can affect the respiratory system and cause bladder retention problems. Patients may also experience behavioural changes which can be misdiagnosed as psychiatric illness. Japanese Encephalitis can be fatal in 20% to 30% percent of cases and many survivors continue to have long term neurologic, psychiatric, or cognitive problems. Treatment includes supportive care of symptoms. Prevention: Travellers should take measures to prevent mosquito bites both indoors and outdoors, especially during the evening and night time. Insect-bite prevention measures include applying a DEET-containing repellent to exposed skin, applying permethrin spray (or solution) to clothing and gear, wearing long sleeves and pants, getting rid of water containers around dwellings and ensuring that door and window screens work properly. Vaccination: Recommended for persons travelling extensively in rural areas, long term travellers, and persons on working assignments in endemic areas. The inactivated Vero cell vaccine is available in Canada, the USA and select countries. Booster vaccination is recommended 1-2 years if you are at continued risk of exposure. Live attenuated vaccines are available in Japanese Encephalitis endemic countries where they are given as part of the childhood routine immunization schedule. Discuss your options with a healthcare provider if you can’t finish the vaccination series before departure. The infection is endemic in the southern plains bordering India (Terai Districts). Cases have also been reported from the highlands, including the Kathmandu valley. Transmission occurs from June to October.