Japanese encephalitis is a virus that is spread by mosquitoes. It can cause swelling of the brain. It also affects the central nervous system. Japanese encephalitis can cause severe complications, like long-term neurological disability and death.
People get Japanese encephalitis when they are bitten by a mosquito infected with the virus. Japanese encephalitis is a common cause of viral encephalitis in Asia. It can be prevented with a vaccine.
Many people with the infection may have no symptoms. If symptoms develop, they can include:
Symptoms of Japanese encephalitis usually appear 5-15 days after the bite from an infected mosquito.
There is no specific treatment for this condition. Care for people with the disease is aimed at easing symptoms.
The vaccine is made from an inactive form of the virus. It is called Ixiaro and is for people aged 17 years and older.
IMOJEV is a vaccine made from live virus that is weakened. It is not available in the United States.
The vaccine is recommended for people who are traveling to Asia and are:
Lab workers who may be exposed to Japanese encephalitis should also get the vaccine.
The vaccine is made from an inactive form of the virus. The IXIARO vaccine is approved for use starting at age 2 months and is the only one available in the US.
IMOJEV is another vaccine made from live virus that is weakened. It is not available in the US.
The Japanese encephalitis vaccine is given in a series of 2 shots within 28 days. The last dose needs to be given within 1 week of traveling to Asia.
Like any vaccine, the Japanese encephalitis vaccine can cause problems, such as severe allergic reactions. The risk of serious harm or death is extremely small.
The most commonly reported problems from the Japanese encephalitis vaccine are mild and include:
Talk to your doctor before getting the vaccine if you:
The vaccine is not 100% effective at preventing the disease. It is important to protect yourself from mosquito bites. The CDC recommends:
In the event of a Japanese encephalitis outbreak, people who are eligible for vaccination should receive it.
WHERE CAN I GET MORE INFORMATION?
Centers for Disease Control and Prevention
Immunization Action Coalition
Immunization schedules. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/schedules/index.html. Updated February 6, 2017. Accessed December 7, 2017.
Japanese encephalitis. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/japaneseencephalitis. Accessed August 5, 2015. Accessed December 7, 2017.
Japanese encephalitis VIS. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/je-ixiaro.html. Updated January 24, 2014. Accessed December 7, 2017.
Mosquito avoidance. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115142/Mosquito-avoidance . Updated November 21, 2016. Accessed December 7, 2017.
Vaccine is key to preventing outbreaks of Japanese encephalitis. UNICEF website. Available at: https://www.unicef.org/immunization/india_28555.html. Accessed December 7, 2017.
Last reviewed November 2018 by
EBSCO Medical Review Board
David L. Horn, MD, FACP
Last Updated: 12/7/2017