Japanese encephalitis is a viral disease. It is the leading cause of viral encephalitis in Asia, with up to 50,000 cases reported each year. The death rate among persons with symptoms of Japanese encephalitis is 30%, with another 30% having serious neurological complications. However, the risk for most travelers is very low, with fewer than 1 case per million travelers. However, rates increase for those staying for prolonged periods in areas where Japanese encephalitis is common.
Japanese encephalitis is transmitted by infected mosquitoes. When an infected mosquito bites a human, the virus is transferred. In addition, wading birds and pigs can be infected and also transfer the virus back to mosquitoes when bitten by a mosquito. Japanese encephalitis transmission occurs mainly in agricultural and rural areas, especially during summer and fall when conditions result in large amounts of standing water.
Most human infections with Japanese encephalitis do not have symptoms. However, a small percentage of those infected develop a sudden fever, headache, and vomiting about 5 to 15 days after infection. These symptoms are followed by mental status changes, neurological changes, weakness, and movement disorders. Seizures are also common, especially among children. There is no specific treatment for Japanese encephalitis. Therapy mainly consists of supportive care and management of complications. The primary public health approaches to JE prevention is through vaccination and the use of other protective measures in at-risk populations.
Currently, there is only one Japanese encephalitis vaccine. It
is approved by the FDA for use among persons 2 months of age and older.
Product: Ixiaro® (Inactivated Japanese Encephalitis Vaccine)
Manufacturer: Intercell Biomedical
Year licensed: 2009
* To administer a 0.25 mL dose, expel and discard half of the volume from the 0.5 mL pre-filled syringe by pushing the plunger stopper up to the edge of the red line on the syringe barrel prior to injection.
To administer a 0.25 mL dose, expel and discard half of the
volume from the 0.5 mL pre-filled syringe by pushing the plunger stopper
up to the edge of the red line on the syringe barrel prior to
IXIARO® is an inactivated virus vaccine injected intramuscularly in a two-dose series. Doses are administered on day zero (the day of initial immunization) and on day twenty-eight. The IXIARO® series should be completed at least one week prior to potential exposure to JEV. IXIARO® only comes in 0.5 mL pre-filled syringes.
A one-time booster dose is recommended for persons 17 years and older if more than one year has passed since completing the primary series and the risk of exposure to the JE virus continues. Timing of additional booster doses has not yet been determined. IXIARO® cannot be used as a booster dose for previously administered JE-Vax®. Previous doses of JE-Vax® are considered void, and the two dose series of IXIARO® should be administered for continued protection against JE.