Japanese encephalitis (JE) is a serious infection caused by a virus. It occurs mainly in rural parts of Asia. Japanese encephalitis virus spreads through the bite of infected mosquitoes. It does not spread from person to person.
The risk of Japanese encephalitis is very low for most travelers, but it is higher for people living or traveling for long periods in areas where the disease is common. Most people infected with Japanese encephalitis virus do not have any symptoms at all. Others might have symptoms as mild as a fever and headache, or as serious as encephalitis (brain infection).
Symptoms of encephalitis are fever, neck stiffness, seizures, changes in consciousness, or coma. About 1 person in 4 with encephalitis dies. Of those who do not die, up to half may suffer permanent brain damage. There is some evidence that an infection in a pregnant woman can harm her unborn baby.
How can I prevent Japanese encephalitis (JE)?
- The best way to prevent Japanese encephalitis is to avoid mosquito bites.
- Japanese encephalitis vaccine can help protect travelers from Japanese encephalitis disease.
Japanese encephalitis vaccine: Two types of Japanese encephalitis vaccine are the most common used.
- CD.JEvax®: For persons at least 9 months of age and older; administer primary immunization of single dose 0.5 milliliter subcutaneously. Then booster dose can be given from 3 months to 1 year after the first vaccination.
- Imojev®: For persons from 9 months to 17 years of age, administer a single dose (0.5 milliliter) subcutaneously. In children and adolescents up to 18 years of age, if long-term protection is required, a booster dose should be given preferably 1 year after the first vaccination and can be given up to 2 years after first vaccination
Who should get Japanese encephalitis vaccine?
Japanese encephalitis vaccine is recommended for travelers to Asia who:
- Plan to live in a country where Japanese encephalitis occurs,
- Plan to visit a country where Japanese encephalitis occurs for long periods (e.g., one month or more)
- Frequently travel to countries where Japanese encephalitis occurs.
It should also be considered for travelers spending less than one month in a country where Japanese encephalitis occurs, if they:
- Will visit rural areas and have an increased risk for mosquito bites,
- Are not sure of their travel plans.
Many laboratory workers at risk for exposure to Japanese encephalitis virus will also require vaccination.
Who should not get Japanese encephalitis vaccine?
- Persons with a proven or suspected history of hypersensitivity/anaphylactic reaction to any component of the vaccine.
- Persons with fever, acute infectious disease, tympanitis or active untreated tuberculosis.
- Persons with malnutrition, general allergy and convulsion.
- Persons with cardiac, liver or kidney troubles.
- Persons undergoing any type of immunosuppressive therapy.
- Persons with a weak or not proper functioning immune system.
What are undesirable effects of Japanese encephalitis vaccine?
- Fever sometimes happens (more often in children)
- Headache or muscle aches can occur (mainly in adults).
- Pain, tenderness, redness, or swelling where the shot was given are common after Japanese encephalitis vaccine.
- Crying, loss of appetite, sleepiness or sleep problems (in children).
Studies have shown that severe reactions to Japanese encephalitis vaccine are very rare.
What to do if you missed a dose?
Contact your doctor if you miss a booster dose or if you get behind schedule. The next dose should be given as soon as possible. There is no need to start over.
Interaction with other medical products
Currently no clinical data is available of administration of Japanese encephalitis vaccine at the same time with any other vaccine. However, it is advisable to observe a period of at least 2 to 4 weeks when given prior or after to Japanese encephalitis vaccine.
Japanese encephalitis vaccination must not be performed within 6 weeks of injection of immunoglobulins or blood products containing immunoglobulins.
Storage
Store refrigerated at 2-8 degrees Celsius. Protect from light.
References
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Last modify: March 26, 2025