Japanese Encephalitis Vaccine Overview

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:

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

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.

The vaccine is made from an inactive form of the virus. There are two types:

• JE-VAX—for children and teens younger than 17 years old

• Ixiaro—for people aged 17 years and older

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

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

Lab workers should also get the vaccine.

JE-VAX, for children and teens, is given in a series of three shots within one month. The last dose needs to be administered at least 10 days prior to traveling to Asia.

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.

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:

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

Rare problems include:

• Seizure
• Nervous system problems
• Severe allergic reactions including:

• Rash
• Swelling of the hands and feet, face, or lips
• Breathing difficulty

Talk to your doctor before getting the vaccine if you:

• Have ever had a life-threatening reaction to this vaccine

• Have severe allergic reactions

• Are pregnant or nursing

• Will be traveling to an urban area for less than 30 days

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

• Wearing clothes that cover most of the body

• 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

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

WHERE CAN I GET MORE INFORMATION?

Immunization Action Coalition
http://www.immunize.org/

Vaccine and Immunizations
Centers for Disease Control and Prevention
http://www.cdc.gov/vaccines/

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.

UNICEF website. Available at: http://www.unicef.org/infobycountry/india_28555.html . Accessed February 2, 2007.

Halstead SB, Thomas SJ. Japanese encephalitis: new options for active immunization. Clin Infect Dis.2010;50(8):1155-1164.

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 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.