Japanese encephalitis is a viral infection of the brain, which is caused by mosquito bites. The virus is found in birds and pigs and is carried by mosquitoes when they bite animals that have been infected. It cannot be spread from person to person.
The infection is most common in rural areas in the Pacific islands, the Far East and Southeast Asia. It is very rare for travellers to contract the infection.
Most people who contract Japanese encephalitis either have mild flu-like symptoms or no symptoms at all.
However, 1 in 250 infected do develop more serious symptoms, which usually takes place between 5 to 15 days.
These more serious symptoms include:
- a stiff neck
- the Inability to speak
- muscle weakness or paralysis
- a high temperature
Japanese encephalitis will prove fatal for up to 1 in 3 people who exhibit these more serious symptoms.
Those who survive will take several months to make a full recovery and even then, up to half of those people will be left with permanent brain damage. This could then lead to more long-term issues, including:
- muscle twitches or weakness
- learning difficulties
- paralysis in 1 or more limbs
- personality changes
There is currently no cure for Japanese encephalitis. People who contract the infection will usually need to be admitted to hospital to receive fluids, oxygen and medication to treat symptoms and support the body as it fights the infection.
Prevention and Vaccination
There is a vaccine for Japanese encephalitis, which has been shown to protect over 9 out of 10 people who get it.
You should seriously consider getting this vaccine if you are planning on:
- Visiting rural areas in a high-risk country
- Visiting a high-risk area in the rainy season
- Visiting a high-risk area where there is a tropical climate
- Staying at least a month in a high-risk country
- Taking part in activities that may increase the risk of infection in a high-risk country (e.g., cycling, hiking or camping).
In the UK, the Japanese encephalitis vaccine is available for adults and children over 2 months old. The course of vaccination consists of 2 injections with the second dose being administered 28 days after the first. If you are between the ages of 18 and 64 you can receive the second dose after 7 days on an accelerated schedule. A booster dose of the vaccine should be given 12 to 24 months after you were first vaccinated if you are still planning on travelling to places of high risk.
Mild and short-lived side effects of the vaccine may include:
- soreness, swelling or redness at the injection site
- muscle pain
- a headache
Up to 40% of people who receive the vaccine experience these side effects. More serious side effects are rare.
During your consultation with an Ahemys travel health practitioner, you will undertake a travel risk assessment based on your itinerary and travel plans. Our expert practitioners are also well placed to discuss and assess the risks versus the benefits of vaccination of those who are pregnant or who suffer from certain allergies. Our aim is for you to leave your consultation feeling confident and fully informed.
Even if you have been vaccinated, you should still take precautions to reduce your risk of being bitten by an infected mosquito, such as:
- Using a quality insect repellent on exposed areas of skin
- Wearing long-sleeved tops, trousers and socks
- Sleeping in rooms with close-fitting gauze over the doors and windows
- Using a mosquito net sprayed with insect repellent