Japanese encephalitis is a viral disease found in South-East Asia and the Indian subcontinent. The infection is spread by the bite of an infected mosquito. This particular type of mosquito favours breeding sites in and around rice paddies. The mosquito bites mostly around dusk.
Transmission patterns are highly specific to locations and vary year to year; in some countries transmission is seasonal and in others, disease occurs all year round.
Japanese encephalitis causes headache, convulsions, encephalitis and meningitis. Most people will have a mild illness with no or few symptoms but for those with severe disease around 30% can develop permanent neurological problems and around 30% will die from the disease.
There is no specific treatment available for Japanese encephalitis.
Prevention is focused on avoiding mosquito bites, especially around dusk when this mosquito is most active. Use of insect repellents, appropriate clothing and mosquito nets is recommended for those at risk.
- Tips on how to avoid mosquito bites
The vaccine most commonly used in the UK is IXIARO; 2 doses of vaccine should be given before travel. The risk for most travellers will be very small. Individuals should consider being vaccinated:
- If travelling to a country where Japanese encephalitis is present and where the stay may be prolonged (e.g. more than four weeks).
- If at increased risk of exposure to the disease e.g. staying in or around rice growing areas.
- If having prolonged periods outdoors in rural areas.
- For shorter, but frequent trips to endemic areas.
- If going to live in an endemic area.