Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Japanese Encephalitis Vaccine

by Krisha McCoy, MS
What Is Japanese Encephalitis?

Japanese encephalitis is a mosquito-borne virus that leads to swelling of the brain. It can affect the central nervous system and 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 the leading cause of viral encephalitis in Asia.

Symptoms include:

  • Agitation
  • Brain damage
  • Chills
  • Coma
  • Confusion
  • Convulsions (especially in infants)
  • Fever
  • Headache
  • Nausea
  • Neck stiffness
  • Paralysis
  • Tiredness
  • Tremors
  • Vomiting

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 treats specific symptoms and problems.

What Is the Japanese Encephalitis Vaccine?

The vaccine is made from an inactive form of the virus. There is the only type available in the United States:

  • Ixiaro—for people aged 17 years and older

IMOJEV is a vaccine made from live attenuated virus. It is not available in the United States.

Who Should Get Vaccinated and When?

The vaccine is recommended for people who are traveling to Asia and are:

  • Going to an area of Japanese encephalitis outbreaks
  • Planning on staying less than a month, but will be in rural areas or outdoors a lot
  • Planning to stay at least a month where there have been Japanese encephalitis outbreaks
  • Unsure of where they will be staying

Lab workers should also get the vaccine.

There is no vaccine available in the United States for young children. Children under age 17 who will be traveling to a high-risk area can visit a travel clinic abroad or enroll in a clinical trial. Visit the Centers for Disease Control and Prevention website for more information: http://www.cdc.gov/.

Ixiaro is given in a series of two shots within 28 days. The last dose needs to be given within one week of traveling to Asia.

What Are the Risks Associated With the Japanese Encephalitis Vaccine?

Like any vaccine, the Japanese encephalitis vaccine is capable of causing problems, such as severe allergic reactions. The risk of serious harm or death is extremely small.

The most commonly reported problems associated with the Japanese encephalitis vaccine are mild and include:

  • Abdominal pain
  • Chills
  • Diarrhea
  • Dizziness
  • Fever
  • Headache
  • Muscle pain
  • Nausea or vomiting
  • Rash
  • Soreness, redness, or swelling near the injection site

Rare problems include:

  • Severe allergic reactions including:
    • Breathing difficulty
    • Rash
    • Swelling of the hands and feet, face, or lips
  • Nervous system problems
  • Seizure
Who Should Not Get Vaccinated?

Talk to your doctor before getting the vaccine if you:

  • Are pregnant or nursing
  • Have ever had a life-threatening reaction to this vaccine
  • Have severe allergic reactions
  • Will be traveling to an urban area for less than 30 days
What Other Ways Can Japanese Encephalitis Be Prevented Besides Vaccination?

Since the vaccine is not 100% effective at preventing the disease, it is important to protect yourself from mosquito bites. The Centers for Disease Control and Prevention (CDC) recommends:

  • Remaining in well-screened areas
  • Using an effective insect repellent (eg, those containing up to 30% N,N-diethyl metatoluamide, or "DEET") on skin and clothing to prevent mosquito bites
  • Wearing clothes that cover most of the body
What Happens in the Event of an Outbreak?

In the event of a Japanese encephalitis outbreak, people who are eligible for vaccination should receive it.

Last reviewed: November 2011 by Lawrence Frisch, MD, MPH.

References:
  • Directors of Health Promotion and Education website. Available at: http://www.dhpe.org/?Input=Japanese+encephalitis&image.x=20&image.y=14# . Accessed February 2, 2007.
  • Dubischar-Kastner K, Kaltenboeck A, Klingler A, Jilma B, Schuller E. Safety analysis of a Vero-cell culture derived Japanese encephalitis vaccine, IXIARO (IC51), in 6 months of follow-up. Vaccine. 2010;28(39):6463-6469.
  • Fischer M, Lindsey N, Staples JE, Hills S; Centers for Disease Control and Prevention (CDC). Japanese encephalitis vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2010;59(RR-1):1-27.
  • Halstead SB, Thomas SJ. New Japanese encephalitis vaccines: alternatives to production in mouse brain. Expert Rev Vaccines. 2011;10(3):355-364.
  • Halstead SB, Thomas SJ. Japanese encephalitis: new options for active immunization. Clin Infect Dis. 2010;50(8):1155-1164.
  • Japanese encephalitis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/. Updated June 2, 2011. Accessed November 3, 2011.
  • Lehtinen VA, Huhtamo E, Siikamäki H, Vapalahti O. Japanese encephalitis in a Finnish traveler on a two-week holiday in Thailand. J Clin Virol. 2008;43(1):93-95.
  • UNICEF website. Available at: http://www.unicef.org/infobycountry/india_28555.html . Accessed February 2, 2007.
  • Wilder-Smith A, Halstead SB. Japanese encephalitis: update on vaccines and vaccine recommendations. Curr Opin Infect Dis. 2010;23(5):426-31.
  • US Centers for Diseaes Control and Prevention. Clinical trials sites in the United States for Ixiaro in children under 17. Available at http://www.cdc.gov/ncidod/dvbid/jencephalitis/resources/UpdtJEVaccChildren_Web_Table1.pdf. Accessed October 30, 2011.
  • US Centers for Disease Control and Prevention. Japanese encephalitis vaccine: JE-VAX. US Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/vaccines/pubs/vis/downloads/vis-je-jevax.pdf . Updated March 1, 2010. Accessed October 7, 2010.
  • US Centers for Disease Control and Prevention. Japanese encephalitis vaccine: Ixiaro. US Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/vaccines/pubs/vis/downloads/vis-je-ixiaro.pdf . Updated March 1, 2010. Accessed October 7, 2010.