Around a third of people who have severe Japanese encephalitis suffer from long-term complications.1
Risk areas for Japanese Encephalitis
When you’re bitten by mosquitoes carrying the virus.1
Asian countries from India to Japan (see map). The risk is greater in rural areas.2
Most people experience no symptoms as a result of their infection. Those that do experience sudden onset of high fever, chills, headache, muscle pain, mental confusion, spasms in the neck and spine, and muscle weakness.1
Symptoms usually occur between 4 and 14 days after being bitten, therefore you may start to feel ill when you are back home after your trip.1
For almost all people who have the virus, the flu-like symptoms pass quickly. In rare cases, encephalitis develops when the virus spreads to the brain. This may cause fatal damage in 20-30% of severe cases.1
People who survive severe encephalitis can end up with a long-term disability.
You can take the following precautions to help reduce your risk of infection:
- Visit your nearest convenient pharmacy or specialist travel health clinic for a risk assessment before your trip
- Use a recommended insect repellent containing either Picaridin, DEET, PMD or OLE, IR3535 or 2-undecanone3
- Wear appropriate clothing (e.g loose fitting long-sleeved clothes, long trousers, socks and shoes) to minimise exposed skin4
- Use mosquito nets if you are sleeping or resting in unscreened accommodation or sleeping outdoors during the day or night4
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- World Health Organization. Weekly Epidemiological Record. Japanese Encephalitis Vaccines: WHO Position Paper – February 2015. Available online: https://www.who.int/wer/2015/wer9009.pdf?ua=1 (Last accessed May 2021)
- Centers for Disease Control and Prevention. Yellow Book 2020. Chapter 4 Travel-Related Infectious Diseases. Japanese Encephalitis. June 2019. Available online: https://wwwnc.cdc.gov/travel/yellowbook/2020/travel-related-infectious-diseases/japanese-encephalitis (Last accessed May 2021)
- Centers for Disease Control and Prevention. Yellow Book 2020. Chapter 3 Environmental Hazards & Other Noninfectious Health Risks. Mosquitoes, Ticks, & Other Arthropods. July 2019. Available online: https://wwwnc.cdc.gov/travel/yellowbook/2020/noninfectious-health-risks/mosquitoes-ticks-and-other-arthropods (Last accessed April 2019)
- Public Health England. Mosquito bite avoidance for travellers. August 2017. Available online: https://www.gov.uk/government/publications/mosquito-bite-avoidance-for-travellers (Last accessed May 2021)
UK-BOTB-2100024 May 2021