In short: Japanese encephalitis (JE) is a mosquito-borne viral infection found mainly in rural parts of Asia and the western Pacific. Most infections cause no symptoms, but around 1 in 250 leads to severe brain inflammation, which can be fatal or cause lasting disability. Prevention relies on avoiding mosquito bites and, for travellers at higher risk, vaccination, which is recommended after an individual assessment of your itinerary.

This guide, written by a Ready Health prescribing pharmacist, summarises UKHSA Green Book and TravelHealthPro guidance on Japanese encephalitis for UK travellers.

What is Japanese encephalitis?

JE is caused by a flavivirus spread mainly by Culex mosquitoes, which pick up the virus from pigs and wading birds. These mosquitoes breed in rice paddies and irrigated farmland and mostly bite from dusk to dawn. People cannot pass the infection to each other.

Where is Japanese encephalitis a risk?

JE occurs in much of South and Southeast Asia and East Asia, including parts of India, Nepal, Bangladesh, Sri Lanka, China, Vietnam, Thailand, Cambodia, Laos, Myanmar, Indonesia and the Philippines, as well as Papua New Guinea and parts of the western Pacific. Mainland Australia has reported cases since 2022. Risk is highest in rural agricultural areas, and in temperate regions it is seasonal (typically during and after the rainy season), while in tropical areas transmission can occur year round. Check the country pages on TravelHealthPro for current information.

What are the symptoms of Japanese encephalitis?

Symptoms, if they occur, usually start 4 to 14 days after the bite. Early symptoms include fever, headache, vomiting and tiredness. In severe cases the infection progresses to encephalitis, which may cause:

neck stiffness, confusion and disorientation
seizures, especially in children
weakness or paralysis
coma

Among people who develop symptoms, up to 30% may die, and 20 to 30% of survivors have permanent problems such as paralysis, seizures, or speech and behavioural difficulties. There is no specific antiviral treatment; care is supportive. Seek urgent medical help for fever with headache, confusion or seizures during or after travel.

Do I need the Japanese encephalitis vaccine?

The vaccine is not needed for everyone travelling to Asia. UK guidance suggests it is generally recommended for:

people staying for a month or longer in a risk area during the transmission season
frequent travellers to risk areas
people living in risk areas
laboratory staff who may be exposed to the virus

Shorter trips may also warrant vaccination if your activities increase the risk, for example spending time in rice fields or near pig farms, camping, cycling or trekking in rural areas. Short stays limited to towns and cities usually do not need it. A travel clinician will weigh up your destination, season, length of stay, accommodation and activities.

How is the Japanese encephalitis vaccine given?

The JE vaccine used in the UK is an inactivated (non-live) vaccine given by injection and licensed from 2 months of age.

Schedule	Doses	Who
Standard	Two doses, 28 days apart	Children from 2 months and adults
Rapid	Two doses, 7 days apart	Licensed for adults aged 18 to 64; may be considered for others when time is short
Booster	One dose, usually 12 to 24 months after the primary course	People who remain at risk or will travel again

The course should ideally be completed at least one week before possible exposure. The JE vaccine is not available free on the NHS for travel. Whether it is appropriate for you is decided by a clinician after assessment.

How can I avoid mosquito bites?

Use a repellent containing DEET (50% is commonly recommended), or an alternative such as icaridin if DEET is not suitable
Wear long sleeves and trousers, particularly from dusk to dawn
Sleep in screened or air-conditioned rooms, or under an insecticide-treated net

Frequently asked questions

Is Japanese encephalitis common in travellers?

No, it is rare in travellers. However, because the illness can be so serious, vaccination is recommended for those at higher risk.

Is the Japanese encephalitis vaccine free on the NHS?

No. It is a private travel vaccine in the UK.

Can children have the vaccine?

Yes, from 2 months of age, with a smaller dose for children under 3 years.

What if I am travelling soon?

A rapid schedule with doses 7 days apart may be an option for some adults. Bite avoidance remains essential either way.

Key takeaways

JE is a rare but serious mosquito-borne infection in rural Asia and the western Pacific.
Most infections are silent, but severe cases can be fatal or cause lasting harm.
Vaccination is recommended for longer stays, frequent travel or higher-risk activities.
Bite avoidance is important for every traveller to risk areas.

Sources and further reading

Last reviewed: October 2026 by Shamir Patel, Independent Prescribing Pharmacist, Ready Health. This article is general information and does not replace advice from your own clinician.

Travelling to Asia? Read more about our Japanese encephalitis vaccination service or book a travel health consultation at Ready Health in Standish, Wigan, convenient for Chorley and Bolton. A clinician will assess whether the vaccine is recommended for your trip.