Japanese encephalitis

Japanese encephalitis is spread by infected mosquitoes. It is usually mild, but in some cases it can cause inflammation (swelling) of the brain (encephalitis), leading to permanent brain damage or death.

High-risk areas

High-risk areas for Japanese encephalitis include tropical northeast Australia and east Asia, including:

  • Cambodia
  • China
  • India
  • Indonesia
  • Korea
  • Laos
  • Malaysia
  • Myanmar (Burma)
  • Nepal
  • Philippines
  • Singapore
  • Sri Lanka
  • Thailand
  • Vietnam

The Japanese encephalitis vaccination is recommended for anyone travelling to a high-risk area who will be:

  • staying for a month or longer, especially in rural areas or just after or during the monsoon season
  • visiting rice fields or travelling close to pig farming areas, even if only for a short time
  • cycling, camping or working in fields, even if only for a short time

The vaccine

There are two vaccines available for Japanese encephalitis. Ideally, they need to be completed a month before you leave. The preferred vaccine requires two doses, with the second dose given 28 days after the first. This vaccine is only licensed for people aged over 18.

The other vaccine consists of three doses and is suitable for children older than one.  The second dose is given seven days after the first, and the third dose is given 28 days after this. This vaccine needs to be completed at least 10 days before you leave, in case you have an allergic reaction.

Both vaccines will require a booster after one year. The Japanese encephalitis vaccine is not suitable for babies younger than one.

The course can sometimes be accelerated. This involves two doses being given one week apart, or three doses with a week in between each dose. This still needs to be completed at least 10 days before you travel. You will need to have a booster three months later.