Japanese Encephalitis

Japanese Encephalitis, which is caused by a virus called the Flavivirus, is transmitted by mosquitoes. Previously an endemic disease in Japan, China and Korea, it has now spread to South East Asia, in Thailand, Indonesia, Vietnam, India, Burma and Srilanka.

Japanese Encephalitis

Japanese Encephalitis [Illustration by Anup Singh]

About 85 per cent of the people affected are children less than 15 years of age and about 10 per cent are over 60 years of age. After being bitten by an infected mosquito, the patient will take between 5-15 days to recover.

The Japanese Encephalitis virus can infect several animals and birds, such as pigs, cattle and ardeid birds.


  • Fever, headache, malaise last for about one to six days in what is called the acute encephalitic stage. Some patients experience very high fever, convulsions and sometimes slip into a coma.
  • The inflammation disappears after the beginning of the late stage. The temperature becomes normal and all neurological symptoms improve.
  • The fatality rate in Japanese Encephalitis varies between 20 to 40 per cent. In case of severe infection, the patient dies within nine days.

Methods of Control
Fumigate your house and nearby areas to stem breeding of mosquitoes. If you live in a mosquito-prone area and cannot do anything about it, get yourself vaccinated. Children under three years can be administered doses at an interval of seven and fourteen days. A booster dose can follow after a few months to develop complete protection. But, children need revaccination after three years.