- Japanese encephalitis (JE) is a rare disease in travellers, but can have serious consequences (1)
- The disease is endemic in 24 countries in Asia and the Western Pacific, not just in Japan (1)
- JE is caused by bites from Culex mosquitoes which carry the JE virus (1-3)
- JE causes inflammation of the brain, which can cause coma, paralysis and death (2,3)
- Surviving JE sufferers may be left permanently disabled both physically and mentally (1,3)
- There is currently no treatment for JE (2)
- Vaccination and preventing mosquito bites are the only methods of protection (2)
What is JE?
Japanese encephalitis (JE) is a potentially serious disease (2)
which is caused by the virus Flavivirus, and is closely related to Zika virus, dengue fever, Japanese encephalitis, yellow fever and West Nile virus. (1,4)
JE is the main cause of viral encephalitis in Asia. (2)
JE is caused by infection from mosquitoes, mainly the Culex species, which have bitten an animal infected with the JE virus. (1-3) Video XYZ
Where does JE occur?
Adapted from: Centers for Disease Control and Prevention. Yellow Book 2016. Chapter 3 Infectious Diseases Related to Travel. Japanese Encephalitis. July 2015
JE is endemic in 24 countries across Asia and the Western Pacific. (1,2)
Transmission of the virus through mosquitoes occurs mainly in rural agricultural areas, and there is an association with rice cultivation and flood irrigation. In temperate areas of Asia, transmission is seasonal and it is believed that JE disease is highest in the summer and autumn time. In the subtropics and the tropics, JE transmission varies and the disease may occur all year round. (1)
Who is at risk of contracting JE?
Anyone who travels to areas where JE is endemic is at risk of contracting JE. (1) Travellers who are likely to spend time outdoors in rural or agricultural areas or participate in outdoor activities, such as camping, hiking, trekking, biking, fishing, hunting or farming are at risk. Staying in accommodation without air conditioning, screens or mosquito nets can also put travellers at risk. (2)
What are the symptoms and lasting effects of JE?
Most people infected with JE will not show any symptoms and will not develop the disease. (1) However, in a small number of cases, acute encephalitis is the most common clinical sign of the disease, observed between 5 and 15 days after infection. (1) This shows itself as sudden onset of fever, headache and vomiting, which progresses to inflammation of the brain. The infected person’s mental state may deteriorate, there may be neurological changes, physical weakness and movement disorders, such as tremors and rigidity, and seizures can cause coma or paralysis. (1-3) JE causes death in up to a third of cases. (1,2) Among survivors of JE, one third to a half of all sufferers will have irreversible neurologic, cognitive, or psychiatric disabilities. (1)
How can JE be treated
There is currently no specific treatment for JE – prevention is the only way of protecting against the disease. (1,2)
- Centers for Disease Control and Prevention. Yellow Book 2016. Chapter 3 Infectious Diseases Related to Travel. Japanese Encephalitis. July 2015. wwwnc.cdc.gov
- Centers for Disease Control and Prevention. Japanese Encephalitis. Frequently Asked Questions. August 2015. cdc.gov
- PATH. Landmark protection for Asia’s children. path.org
- Fit for Travel. Zika Virus Infection. fitfortravel.nhs.uk