Japanese encephalitis is the leading cause of viral encephalitis in Asia, where 30,000 to 50,000 cases are reported each year. The disease is rare, however, in American travelers to Asia.
The chance that a traveler to Asia will get Japanese encephalitis is small:
- Only certain mosquito species can spread Japanese encephalitis
- In areas infested with mosquitoes, only a small portion are usually infected with the virus
- Among people who are infected by a mosquito bite, only 1 in 50 to 1 in 1,000 will develop an illness.
On average, less than one case per year of Japanese encephalitis is reported in American civilians and military personnel traveling to and living in Asia. Since 1981, only five cases among Americans traveling or working in Asia have been reported.
Anyone can get Japanese encephalitis, but some people are at an increased risk, including:
- People living in rural areas where the disease is common
- Active-duty military personnel deployed to areas where the disease is common
- Travelers to rural areas where the disease is common (very small increased risk).
There is no specific treatment for Japanese encephalitis. Antibiotics are not effective against viruses, and no effective antiviral drugs have been discovered. Care is focused on treatment of symptoms and complications.
A vaccine is licensed for use in American travelers to rural areas where Japanese encephalitis is common. The vaccine is recommended only for people who plan to travel in these areas for four weeks or more, except in special circumstances, such as an ongoing outbreak of disease.
Because of the potential for other mosquito-borne diseases in Asia, all travelers should take steps
to avoid mosquito bites. The mosquitoes that transmit Japanese encephalitis feed mainly outside during the cooler hours at dusk and dawn. Travelers should minimize outdoor activities at these times, use mosquito repellent on exposed skin, and stay in air-conditioned or well-screened rooms. Travelers to rural areas should use a bednet and aerosol room insecticides.