Japanese encephalitis

Last Updated: July 3, 2026

Key Points

Serious infection from mosquito bites
Mainly found in rural areas of Asia
Vaccine available for travelers
Can lead to severe brain issues
Most people have no symptoms

Overview

Japanese encephalitis is a rare but serious viral infection spread by mosquito bites. It is not found in the UK but is present in rural areas of Asia, including parts of South Korea, Indonesia, and Southeast Asia. While most people infected show no symptoms, some develop flu-like illness. In a small number of cases, the virus can spread to the brain, causing severe and potentially life-threatening complications. These serious symptoms require urgent medical attention and hospital treatment. There is no specific cure, so treatment focuses on managing symptoms and providing supportive care. Vaccination is recommended for travelers at higher risk, alongside measures to prevent mosquito bites.

Signs and Symptoms

No symptoms for most people
Headache
High temperature
Feeling or being sick
Tummy pain
Severe headache (serious cases)
Confusion (serious cases)
Paralysis (serious cases)
Seizures (serious cases)
Loss of consciousness (urgent)
Severe difficulty breathing (urgent)

Things That Increase the Risk

Travel to rural areas of Asia
Staying for over a month in risk areas
Visiting rice fields or wetlands
Being near pig farms
Not using mosquito bite prevention

Diagnosis

Medical evaluation of symptoms
Review of recent travel history
Assessment for neurological signs
Urgent medical consultation for symptoms after travel

Treatment & Management

Hospital care for severe cases
Medicines to relieve symptoms
Painkillers
Steroids
Supportive medical care
Management of long-term effects

Prevention

Use insect repellent (50% DEET)
Sleep under insecticide-treated nets
Wear long-sleeved clothing
Get the Japanese encephalitis vaccine
Seek travel health advice before travel

Available Treatments

Explore our range of treatment options for Japanese encephalitis: