Japanese encephalitis virus kills 27 people in this Indian state; check signs and symptoms

REPRESENTATIONAL IMAGE (CREDITS: WHO)

New Delhi: The Japanese encephalitis (JE) virus has killed four more persons in Assam, pushing the toll to 27 this month, according to a release issued by the National Health Mission on Saturday (July 16, 2022). All four deaths were reported from the Jorhat district. The state also reported nine fresh cases on Saturday taking the tally to 169 this month.

Three fresh cases were reported from the Golaghat district, two each from Sivasagar and Sonitpur along with one each from Goalpara and Kokrajhar districts. Earlier, Assam had recorded four deaths and 16 new cases of Japanese encephalitis on Friday.

What is Japanese encephalitis virus?

Japanese encephalitis virus is a mosquito-borne flavivirus and belongs to the same genus as dengue, yellow fever, and West Nile viruses. It is the most important cause of viral encephalitis in Asia and the first case of Japanese encephalitis viral disease was documented in 1871 in Japan.

According to World Health Organisation (WHO), nearly 68,000 clinical cases of Japanese encephalitis are reported globally each year, with approximately 13,600 to 20,400 deaths. 

Japanese encephalitis primarily affects children and most adults in endemic countries have natural immunity after childhood infection, but individuals of any age may be affected.

Signs and symptoms of Japanese encephalitis disease

According to WHO, Most Japanese encephalitis infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 250 infections results in severe clinical illness. The incubation period is between 4-14 days. 

In children, gastrointestinal pain and vomiting may be the dominant initial symptoms. Severe disease is characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and ultimately death. The case-fatality rate can be as high as 30% among those with disease symptoms.

Of those who survive, 20%–30% suffer permanent intellectual, behavioural or neurological sequelae such as paralysis, recurrent seizures or the inability to speak.

Transmission of Japanese encephalitis

Japanese encephalitis is transmitted to humans through bites from infected mosquitoes of the Culex species (mainly Culex tritaeniorhynchus). Humans, once infected, do not develop sufficient viraemia to infect feeding mosquitoes. 

The virus exists in a transmission cycle between mosquitoes, pigs, and/or water birds (enzootic cycle). The disease is predominantly found in rural and periurban settings, where humans live in closer proximity to these vertebrate hosts.

In most temperate areas of Asia, the Japanese encephalitis virus is transmitted mainly during the warm season, when large epidemics can occur. In the tropics and subtropics, transmission can occur year-round but often intensifies during the rainy season and pre-harvest period in rice-cultivating regions.