Japanese encephalitis is a viral infection spread by mosquitos that can cause swelling of the brain, resulting in permanent brain damage or death. According to the World Health Organization at least 50,000 people in Asia develop visible symptoms of Japanese encephalitis each year.

Countries at risk

Asia, the Indian subcontinent, and remote parts of northeast Australia.

Risk for travellers

Risk is highest for travellers who are visiting agricultural areas, or those who are travelling to at risk countries for more than three to four weeks.
For temperate countries of Asia including Cambodia, India and Thailand risk is usually highest around the time of the rainy season. In tropical countries like Indonesia, Malaysia and the Philippines, the risk of the disease is year-round.

Signs and symptoms

Symptoms usually occur five to 15 days after being bitten by an infected mosquito. Initially a flu-like illness may occur, which may progress to brain swelling, resulting in symptoms such as high fever, confusion, convulsions, headache, neck stiffness and paralysis. Japanese encephalitis can result in death or permanent brain damage and disability.


There is no specific therapy available for the treatment of Japanese Encephalitis. Intensive care supportive therapy may be required.


A vaccination course of two IXIARO injections may be recommended for travellers considering outdoor activities in high-risk areas, especially during the transmission season. The Japanese encephalitis vaccination is a course of two

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