What is Japanese Encephalitis?

Japanese Encephalitis (JE) is the result of a virus contracted after being bitten by an infected mosquito. It received its name because it’s commonly spread in Asia and the western Pacific through mosquitoes infected with the disease. Encephalitis is inflammation of the brain.

JE is found more often in rural or agricultural areas in Asia and the western Pacific. It is a flavivirus related to dengue, yellow fever and West Nile virus. It is the main cause of viral encephalitis throughout Asia and impacts an estimated 68,000 people each year. JE occurs seasonally (summer and fall) in some areas but is transmitted year-round in other areas.

There is no cure for JE, but it is a vaccine-preventable disease. It can potentially become very severe if a person is symptomatic and leads to long-term disabilities or death.

What are the symptoms and complications of Japanese Encephalitis?

People contract JE when they are bitten by an infected mosquito. Most people who get infected with JE do not have symptoms or may only experience mild symptoms. However, a small portion of people infected (less than one percent) will develop encephalitis. Of those, about one in four cases are fatal.

It can take anywhere from five to 15 days for symptoms to develop after being infected.

Symptoms of encephalitis include:

  • Fever
  • Headache
  • Vomiting
  • Weakness
  • Movement disorders
  • Change in mental status or other neurologic symptoms
  • Seizures (especially in children)

About 20 to 30 percent of the people who develop encephalitis die from the disease. For those who survive, 30 to 50 percent continue to have neurologic, cognitive or other symptoms affecting mental ability.

Who should get the Japanese Encephalitis vaccine?

The best way to protect yourself from JE is by protecting yourself from mosquito bites and getting vaccinated before traveling.

The vaccine is recommended for the following groups:

  • People moving to a JE-endemic country to live
  • Longer-term travelers (1 month or more)
  • Frequent travelers to JE-endemic areas
  • Short-term travelers (less than one month) with increased risk based on travel duration, season, location, activities or accommodations
  • Travelers who are unsure of specific duration, destinations or activities

The vaccine is inactivated Vero cell culture-derived JE and manufactured as IXIARO. It is given as a two-dose series and shots are spread 28 days apart.

Talk with your healthcare provider about whether or not vaccination is right for you.

Is the Japanese Encephalitis vaccine safe?

The JE vaccine is safe and effective for those who need protection when traveling to an area where JE is more common. The vaccine used in the United State was approved in March 2009 for people 17 years of age and older. In May 2013, the vaccine was approved for use in children 2 months of age through 16 years of age.