Japanese encephalitis

Japanese encephalitis
Other names	Japanese B encephalitis
The geographic distribution of Japanese encephalitis (dark green)
Specialty	Infectious disease
Symptoms	Headache, fever, vomiting, confusion, seizures[1]
Usual onset	5 to 15 days after infection[1]
Causes	Japanese encephalitis virus (spread by mosquitoes)
Diagnostic method	Blood or cerebrospinal fluid testing[2]
Prevention	Japanese encephalitis vaccine, avoiding mosquito bites[2]
Treatment	Supportive care[1]
Prognosis	Permanent neurological problems occur in up to half of survivors[2]
Frequency	68,000[2]
Deaths	17,000[2]

Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV).^[3] While most infections result in little or no symptoms, occasional inflammation of the brain occurs.^[3] In these cases, symptoms may include headache, vomiting, fever, confusion and seizures.^[1] This occurs about 5 to 15 days after infection.^[1]

JEV is generally spread by mosquitoes, specifically those of the Culex type.^[2] Pigs and wild birds serve as a reservoir for the virus.^[2] The disease occurs mostly outside of cities.^[2] Diagnosis is based on blood or cerebrospinal fluid testing.^[2]

Prevention is generally achieved with the Japanese encephalitis vaccine, which is both safe and effective.^[2] Other measures include avoiding mosquito bites.^[2] Once infected, there is no specific treatment, with care being supportive.^[1] This is generally carried out in a hospital.^[1] Permanent problems occur in up to half of people who recover from JE.^[2]

The disease primarily occurs in East and Southeast Asia as well as the Western Pacific.^[2] About 3 billion people live in areas where the disease occurs.^[2] About 68,000 symptomatic cases occur a year, with about 17,000 deaths.^[2] Often, cases occur in outbreaks.^[2] The disease was first described in Japan in 1871.^[2][4]