You can reduce your risk of getting Japanese encephalitis by being vaccinated and taking precautions to avoid mosquito bites.
Japanese encephalitis vaccination
The vaccine gives protection for more than 9 out of every 10 people who have it.
You should get vaccinated if you're:
- planning a long stay in a high-risk country (usually at least a month)
- visiting a high-risk area during the rainy season or where there's a year-round risk because there's a tropical climate
- visiting rural areas in a high-risk country, such as rice fields, marshlands or somewhere close to pig farms
- taking part in activities while in a high-risk country that may increase your risk of becoming infected, such as cycling or camping
- working in a laboratory with potential exposure to the virus
The vaccine is not available on the NHS, so you'll need to pay for it.
You can either go to a private travel clinic or a pharmacy that offers travel healthcare services.
The cost can vary between clinics – each dose can cost more than £90 per person.
There's currently 1 vaccine for Japanese encephalitis permitted for use in the UK. This is for adults and children aged 2 months and older.
The vaccine is given as an injection. You need 2 doses for full protection. The second dose is given 28 days after the first.
People aged 18 to 64 may be given the second dose 7 days after the first. This is called an accelerated schedule.
Both doses of the vaccine should be completed at least 7 days before you visit an area where there's a risk of Japanese encephalitis.
If you continue to be at risk of infection, a booster dose of the vaccine should be given 12 to 24 months after you're first vaccinated.
Up to 40% of people who have the Japanese encephalitis vaccine experience mild and short-lived side effects.
- soreness, redness or swelling at the site of the injection
- a headache
- muscle pain
More serious side effects, such as a raised, itchy red rash (urticaria or hives), swelling of the face and difficulty breathing, are rare.
If you develop any worrying symptoms after being vaccinated, contact your GP as soon as possible or call NHS 111 for advice.
Most people can have the Japanese encephalitis vaccination safely, but you should tell the doctor or nurse before being vaccinated if you have a high temperature (fever), or if you're pregnant or breastfeeding.
The vaccination may need to be postponed if you have a fever.
It may also not be recommended if you're pregnant or breastfeeding as there's a theoretical risk of problems resulting from the vaccine being passed to your baby.
The Japanese encephalitis vaccine is not usually recommended for children less than 2 months old because it's unclear how safe and effective it is for this age group.
You should not have the vaccine if you have had a severe allergic reaction (anaphylaxis) to it or any of its ingredients in the past.
Avoiding mosquito bites
As the vaccination against Japanese encephalitis is not 100% effective, you should protect yourself against mosquito bites while travelling or staying in at-risk areas by:
- sleeping in rooms with close-fitting gauze over the windows and doors
- if this is not possible or you're sleeping outside, use a mosquito net that's been impregnated with an insecticide, such as permethrin
- spraying your room with insecticide in the early evening to kill any mosquitoes that have got in during the day
- covering up with long-sleeved tops, trousers and socks – mosquitoes that carry the Japanese encephalitis virus are usually most active at dusk and enjoy warm, humid conditions
- wearing loose-fitting clothes, as mosquitoes can bite through skin-tight clothing
- applying a good-quality insect repellent to any exposed areas of skin
Various types of insect repellent are available. Many contain diethyltoluamide (DEET), but some contain dimethyl phthalate or eucalyptus oil if you're allergic to DEET.
When using insect repellent, make sure you:
- do not use it on cuts, wounds or irritated skin
- do not get it in your eyes, mouth and ears
- do not spray it directly on your face – spray it on your hands and then apply it to your face
- do not allow young children to apply it themselves – put it on your hands and then apply it to your child
- apply it after applying sunscreen, not before
- wash your hands thoroughly after use, and wash the repellent off your skin with soap and water when it's no longer needed
- always follow the manufacturer's instructions
If you or your children have a reaction to an insect repellent, such as redness, stop using it.
Wash it off and contact a GP or a local healthcare professional if you're abroad.
Page last reviewed: 1 February 2019
Next review due: 1 February 2022