Japanese encephalitis is a mosquito-transmitted arbovirus that is present in most countries in Asia. The disease is serious, with about one-third of those infected dying and about one-third of survivors having significant nervous-system problems remaining after recovery.
An inactivated vaccine is available for travelers who will be staying for extended periods (defined as greater than thirty days) in high-risk countries. Because there is a higher than normal risk of allergic reactions, although still low at only 0.6 percent of recipients, the vaccine is not recommended for travelers who are only spending a short amount of time in the high-risk areas. The vaccine is available for everyone over the age of one year and is given in a series of three injectable doses over thirty days.
This is a rarely used vaccine, and we have personally never needed to recommend this vaccine to anyone. However, given the serious nature of the illness, long term travelers to certain parts of Asia should consider receiving the vaccine. We suggest that interested travelers review the information in the Traveler’s Health section of www.cdc.gov.