Site last updated 03/07/2018
Copyright® Sanofi Pasteur 2014
Macquarie Park NSW 2113
This website is for Australian residents only.

Disease Information / Japanese Encephalitis

Japanese Encephalitis

What is it

Japanese encephalitis is a viral disease transmitted by mosquitoes that may cause inflammation of the membranes around the brain.1

Who is at risk and what are the symptoms

Travellers visiting rural Asia are at the highest risk, with children and those aged 65 and over most vulnerable. Following infection, most people don’t develop any symptoms, but in those who do, the disease can be serious. Symptoms include the onset of high fever and headaches, which appear after five to 15 days of incubation. Japanese encephalitis also affects the central nervous system, resulting in behavioural changes and speech and movement disorders.Fatality can result in five to 30% of symptomatic cases and between 30 and 50% of surviving patients have permanent impairment as a result of contracting the disease.2

How is it spread

The viral infection is spread by mosquito bites. It is most common in rural areas of Asia including the Indian subcontinent, South East Asia, China and some parts of the Western Pacific. It is more common in rice fields, which provide favourable conditions for mosquitoes. Infection peaks during the monsoon season between April and December.

How is it prevented

Vaccination for people 9 months of age and over is available for those travelling to high risk areas. Australian travellers are advised to visit their General Practitioner or travel medicine specialist six to eight weeks before travelling overseas to discuss suitable vaccination options. Travellers to areas where the Japanese encephalitis virus may be present are advised to take extra precaution to avoid being bitten by mosquitoes. They should use insect repellent when outdoors and wear light, long sleeved protective clothes. It is often advised that clothes are treated with repellent too. Extra precaution is required between dusk and dawn. Travellers are advised to book accommodation in rooms with air conditioning or adequate screening, like a bed net or aerosol room insecticides.3

How is it diagnosed and treated

There is no specific treatment for Japanese encephalitis. Diagnosis is bases on symptoms, as case-by- case diagnosis requires laboratory diagnosis. 4

Where to get help

Urgent medical advice is recommended for the onset of Japanese encephalitis symptoms. For further information regarding vaccination for Japanese encephalitis contact your healthcare professional.


  1. WHO:
  2. WHO:
  3. Centres for Disease Control and Prevention:
  4. WHO: