Japanese encephalitis

Japanese encephalitis (JEV) is an infectious brain disease that occurs in some parts of Asia and Australia. JE virus is the most common cause of encephalitis in Asia.

Etiology and epidemiology
JEV belongs to the group of arboviruses, it is caused by RNA virus from Flavivirus group. The reservoir represents wild birds, as well as pigs. Rarely, a person may be infected via asymptomatic virus carrier. Mosquitos are the carriers, due to their typical occurrence in water areas and rice fields, the disease is also common in agricultural areas.

Clinical picture
The disease varies in severity from inapparent to severe encephalitis. In 90% of cases, the infection takes place without any clinical signs, but more difficult course is expected for tourists in the given areas. The disease can progress to severe encephalitis. After a 5-15 days incubation period, the manifestations such as fever, chills, headache and joint pain will occur. Patients are tired, we observe changes in consciousness, delirium to unconsciousness. The disease can have a prolonged course. Residual neurological, intellectual or physical disabilities are observed in 30% of patients who experience severe encephalitis.

Diagnostics
To detect a virus, we use the determination of JEV-specific IgM antibodies in cerebrospinal fluid or serum, preferably by PCR diagnostics. In the cerebrospinal fluid we also find a picture typical of aseptic meningitis, a blood count informs us about leukocytosis.

Treatment and prevention
Treatment is symptomatic, patients with an onset encephalitis must be hospitalized in intensive care units (ICU).

An inactivated and live attenuated vaccine is available. In certain Asian countries, preventive vaccination is provided already in childhood. In the Czech Republic, vaccines are available in vaccination centers. Vaccination is usually recommended for those, who travel to endemic areas and will be staying in a rural areas as well.