JAPANESE ENCEPHALITIS

Japanese encephalitis (JE) is a potentially serious mosquito-borne disease found mainly in Asia

OVERVIEWSIGNS & SYMPTOMSDISEASE PROTECTION

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JAPANESE ENCEPHALITIS SYMPTOMS CAN BE SEVERE

Most people infected with JE will not show any symptoms and will not develop the disease.2 However, in a small number of cases (approximately one in 250) severe illness may occur.2

Acute encephalitis is the most recognised clinical manifestation of the severe illness, typically observed between five and 15 days after infection.3

Severe disease shows itself as sudden onset of fever, headache and vomiting, which progresses to inflammation of the brain. The infected person’s mental state may change, and there may be neurological changes, physical weakness and movement disorders such as tremors and rigidity, as well as seizures, coma, or paralysis.2,3

UP TO 30%

of people who develop JE die3

ONLY ~19%

of patients fully recover.*4

UP TO 50%

of survivors suffer lasting disabilities.3

*Based on 144 patients (134 children and 10 adults) with confirmed JEV infection.

UP TO HALF OF ACUTE JAPANES ENCEPHALITIS SURVIVORS SUFFER ENDURING COGNITIVE NEUROLOGICAL OR PHYSICAL DISABILITIES1,2
COGNITIVE5
  • Language impairment
  • Cognitive deficits
  • Learning difficulties
NEUROLOGICAL5
  • Seizures
  • Psychiatric complications
  • Behavioural changes
PHYSICAL6
  • Paralysis
  • Motor neuron weakness
  • Cerebellar & extrapyramidal signs
  • Flexion deformities of arms
  • Hyperextension of legs

JAPANESE ENCEPHALITS IS AN INCURABLE DISEASE

There is currently no treatment for JE.2,6

Vaccination is currently the optimal means of protection, as personal protective measures such as repellents are not 100% effective.6–8

LEARN MORE ABOUT JAPANESE ENCEPHALITIS

Get in-depth information on symptoms, diagnosis, disease protection and more.

JAPANESE ENCEPHALITIS

OVERVIEW

Gain a useful overview of this potentially fatal, mosquito-borne disease.

JAPANESE ENCEPHALITIS

DISEASE PROTECTION

Help protect your patients against the risk of developing JE.

Useful Links
References
  1. NaTHNaC Travel Health Pro. Japanese encephalitis. June 2026. Available at: https://travelhealthpro.org.uk/factsheet/55/japanese-encephalitis. Accessed: July 2026.
  2. World Health Organization. Japanese encephalitis. August 2024. Available at: https://www.who.int/news-room/fact-sheets/detail/japanese-encephalitis. Accessed: June 2026.
  3. Centers for Disease Control and Prevention. Japanese Encephalitis. CDC Yellow Book 2026. February 2026. Available at: https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/japanese-encephalitis.html. Accessed: July 2026.
  4. Solomon T, Dung NM, Kneen R, et al. Seizures and raised intracranial pressure in Vietnamese patients with Japanese encephalitis. Brain. 2002;125(Pt 5):1084-1093.
  5. Prabhu. What happens when you don’t recover from Japanese Encephalitis? January 2023. Available at: https://www.gavi.org/vaccineswork/what-happens-when-you-dont-recover-japanese-encephalitis. Accessed: July 2026.
  6. Yun SI, Lee YM. Japanese encephalitis: the virus and vaccines. Hum Vaccin Immunother. 2014;10(2):263-279.
  7. Centers for Disease Control and Prevention. Preventing Japanese Encephalitis. Japanese Encephalitis Virus. May 2024. Available at: https://www.cdc.gov/japanese-encephalitis/prevention/index.html. Accessed: July 2026.
  8. Centers for Disease Control and Prevention. Mosquitoes, Ticks, and Other Arthropods. Yellow Book. November 17, 2025. Available at: https://www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/mosquitoes-ticks-and-other-arthropods.html. Accessed: July 2026.

UK-JE-2600006 July 2026