Japanese encephalitis - Symptoms of Japanese encephalitis
- Introduction
- Symptoms of Japanese encephalitis
- Causes of Japanese encephalitis
- Preventing Japanese encephalitis
- Treatment
- Diagnosis
- Vaccination
- Complications
In most people, the Japanese encephalitis virus causes either no symptoms or mild, short-lived symptoms, which are often mistaken for flu.
Only around 1 in every 250 people who become infected develops more obvious symptoms of Japanese encephalitis. This usually happens between 5 and 15 days after infection.
Initial symptoms of infection can include:
In some cases, these initial symptoms may be followed a few days later by more serious problems, as the infection spreads to the brain. This is known as encephalitis and it can cause more wide-ranging symptoms, such as:
- seizures (fits)
- stiff neck
- muscle weakness
- changes in mental state – which can range from mild confusion to being very agitated or slipping into a coma
- uncontrollable shaking of body parts (tremor)
- inability to speak
- paralysis (inability to move certain body parts)
Up to one in every three people who develop these more serious symptoms will die as a result of the infection.
In those who survive, these symptoms tend to slowly improve. However, it can take several months to make a full recovery and up to half of those who do survive are left with permanent brain damage. This can lead to long-term problems such as tremors and muscle twitches, personality changes, muscle weakness, learning difficulties and paralysis in one or more limbs.
When to seek medical advice
If you have any of the symptoms of Japanese encephalitis and have recently visited, or are still in, an area where the infection is found, you should seek immediate medical advice.
Visit the GOV.UK website for information about who to contact when you need immediate medical help abroad. If you are already back in the UK, see your GP.
Encephalitis
Encephalitis is inflammation of the brain. This can develop as a result of infection (usually viral) or when the immune system attacks the tissue of the brain by mistake (post-infectious encephalitis).
Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Seizures
The electrical impulses in the brain are disrupted, causing both the brain and the body to behave strangely.
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