Symptoms Japanese encephalitis

Related articles: Japanese encephalitis


Japanese encephalitis is an infectious disease caused by a virus belonging to the genus Flavivirus (to which also the agents responsible for dengue and yellow fever belong).

The transmission of Japanese encephalitis to humans occurs through the bite of mosquitoes of the genus Culex, which become vectors of the virus after feeding on the blood of migratory birds (such as herons) and domestic animals (mainly swine), which represent the infection tank.

Japanese encephalitis is widespread especially in rural and periurban areas of south-east Asia and the western Pacific, but it can also affect urban centers, if favorable conditions exist for the development of mosquitoes.

The risk of getting sick is present all year round, with accentuations in correspondence of the monsoon rains until the beginning of the dry season. In the temperate regions of China, Japan and the Korean peninsula, however, transmission is greater from May to September (period of greater activity of the carriers).

Most common symptoms and signs *

  • Agnosia
  • Apraxia
  • dizziness
  • Coma
  • Convulsions
  • Dysphagia
  • Temporal and spatial disorientation
  • Hemiplegia
  • Temperature
  • Lethargy
  • Headache
  • Loss of coordination of movements
  • Stiffness in the muscles of the back and neck
  • Drowsiness
  • Confusional state
  • Fainting
  • Spastic tetraparesis
  • Tetraplegia
  • Tremors
  • He retched

Further indications

In humans, the period between the infecting puncture and the onset of symptoms can vary from 5 to 15 days.

Infections can be asymptomatic or give rise to different manifestations (such as aseptic meningitis or undifferentiated febrile illness). The actual encephalitis manifests from 1 to 20 cases in 1000 infections and is characterized by the appearance of headache, fever, stiffness of the neck, vomiting, convulsions, alteration of the state of consciousness, motor disorders, spastic paralysis and coma. Sometimes, Japanese encephalitis can present itself as a parkinsonian syndrome or with a clinical picture similar to poliomyelitis.

Japanese encephalitis involves death in almost 20-30% of subjects. Coma, if not fatal, can be resolved in 1-2 weeks. Those who survive can report permanent neurological disorders, such as spastic tetraparesis, hemiplegia, difficulty swallowing, recurrent convulsions, inability to speak and severe cognitive deficits.

Japanese encephalitis is diagnosed with laboratory tests on serum or cerebrospinal fluid.

There is no specific antiviral treatment, but the patient undergoes intense therapy to alleviate symptoms and careful monitoring until the infection is overcome.

In addition to personal protection and environmental control measures, Japanese encephalitis can be prevented by vaccination, which is recommended especially when traveling to endemic areas.


Vitamin loss with food preservation
Peritonsillar abscess