Japanese brain inflammation is a viral disease found in Southeast Asia and much of eastern Asia. The disease is also called Japanese encephalitis and is spread by mosquitoes. The disease is uncommon but can be serious and even life-threatening. You can vaccinate yourself against Japanese brain inflammation.

Symptoms of Japanese brain inflammation

Most often, those who have become infected get mild symptoms, such as mild fever and muscle aches.

Sometimes, but it is unusual, the virus causes severe inflammation of the brain. The symptoms are then:

  • severe headaches
  • high fever
  • overindulge
  • convulsions
  • confusion and worry.

It usually takes between five and ten days from being infected until you get sick.

When and where should I seek care?

Seek immediate medical attention if you have a high fever during a trip abroad in countries where Japanese brain inflammation is present. 

If you have a fever after a foreign trip and suspect that it may be Japanese cerebral inflammation, contact a health center or emergency room immediately. If closed, seek care at an emergency room.

This is how Japanese brain inflammation infects

Japanese brain inflammation is found in Southeast Asia and much of eastern Asia.

Spread through mosquitoes

Japanese brain inflammation infects via infected mosquitoes. Mosquitoes suck blood from pigs and birds that are infected and then transmit the virus when they sting people. The mosquitoes sting mainly in the evenings and nights. The number of mosquitoes increases during rainy periods and in areas where rice cultivation is ongoing.

In the countries of Southeast Asia that have a tropical climate, you can become infected throughout the year. In other countries, the disease is most common between April and October.

The virus does not transmit directly to humans.

How can I prevent Japanese brain inflammation?

There are vaccines against Japanese brain inflammation, which you can take before a trip abroad.

Vaccination is especially recommended if you regularly spend the night in rural areas, visit risk areas for longer than three to four weeks or travel to an area with an ongoing epidemic. The vaccine can be given to children from two months of age and to adults.

The risk of being infected in risk areas

It is very rare to be infected by Japanese brain inflammation even if you travel in countries where the disease is present. The risk of getting infected depends on various things, for example:

  • which country you are traveling to
  • how long you will be there
  • what kind of activities you plan to do
  • what time of year you travel.

Protect yourself from mosquito bites

If you have not been vaccinated, you can try to avoid getting stung by mosquitoes by sleeping under a mosquito net, using mosquito repellent or having air conditioning in the room.


Japanese brain inflammation is caused by a virus and cannot be treated. However, those who have become ill may need to be taken care of in hospitals to relieve the symptoms.


About one-third of those who develop a severe variant of Japanese brain inflammation suffer permanent damage to the central nervous system. For example, it can be cramps, paralysis, memory problems and difficulties in understanding information.

Ehtisham Nadeem

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