Japanese encephalitis is passed to humans by bites from 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: tropical north east Australia and East Asia – including China, Myanmar (Burma), Thailand, Vietnam, Cambodia, Laos, Nepal, India, Philippines, Sri Lanka, Korea, Malaysia, Indonesia, and Singapore.

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

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

The vaccine

There are two possible vaccines for Japanese encephalitis. Ideally, they need to be completed a month before you leave. One vaccine requires two doses, with the second dose given 28 days after the first. This vaccine is only suitable for people who are over 18 years of age.

The alternative vaccine consists of three doses, and is suitable for people who are over one year of age. The second dose is given after seven days, and the third dose is given 21 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 children who are under one year of age.

If there is not enough time to complete a normal course of the vaccine, you may be able to have an accelerated course. 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.