UPSC Express

Japanese Encephalitis

• It is a viral disease that infects animals and humans.
• In humans, it can cause inflammation of membrane around the brain.
• Japanese encephalitis virus (JEV) is the most important cause of viral encephalitis in Asia.
• JEV is a mosquito-borne flavivirus and belongs to the same genus as dengue, yellow fever and West Nile viruses.
• The first case of Japanese encephalitis viral disease (JE) was documented in 1871 in Japan.

Signs and symptoms

• Most JEV infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 250 infections results in severe clinical illness.
• Severe disease is characterised by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and ultimately death.
• Acute encephalitis syndrome (AES) is a clinical condition caused by infection with JEV or other infectious and noninfectious causes.

Transmission

• JEV is transmitted to humans through bites from infected mosquitoes of the Culex species (mainly Culex tritaeniorhynchus).
• Domestic pigs and wild birds are reservoirs of the virus.
• In most temperate areas of Asia, JEV is transmitted mainly during the warm season, when large epidemics occur.
• In the tropics and subtropics, transmission can occur year-round but often intensifies during the rainy season.