Japanese encephalitis is a virus that is spread by mosquitoes. It can cause swelling of the brain. It also affects the central nervous system. Japanese encephalitis can 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 a common cause of viral encephalitis in Asia. It can be prevented by vaccines.

Many people with the infection may have no symptoms. If symptoms develop, they can include:

  • Fever
  • Chills
  • Tiredness
  • Headache
  • Neck stiffness
  • Nausea
  • Vomiting
  • Confusion
  • Restlessness
  • Brain damage
  • Coma
  • Tremors
  • Convulsions, especially in infants

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 is aimed at easing symptoms.

The vaccine is made from an inactive form of the virus. It is called Ixiaro and is for people aged 17 years and older.

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