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How and when is Japanese encephalitis spread?

Page last updated 10 July 2018

Japanese encephalitis (or JE) is spread by the bite of an infected mosquito. The disease cannot be spread from person to person.    

Transmission of JE mainly occurs in rural, agricultural areas of Southeast Asia where standing water is used for rice production and flooding irrigation. In some areas of Asia, these conditions can occur near urban centres. 

JE transmission is seasonal in some areas of Asia, with the disease peaking around summer and autumn. In the more tropical and subtropical regions, such as Thailand, Cambodia and Vietnam, transmission can occur all year round, with a peak during the rainy season from May to October/November. In Indonesia, peak season varies by island. 

In the outer Torres Strait islands, transmission season is December to May. 


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Sources & Citations

  1. NSW Government, Department of Health, Communicable Diseases Factsheet – Japanese Encephalitis. Available at; (accessed 28 March 2018).
  2. Centers for Disease Control and Prevention. Japanese Encephalitis. Available at: (accessed 28 March 2018).
  3. NT Government. Japanese encephalitis. Available at: (accessed 11 May 2018).
  4. Centers for Disease Control and Prevention. Chapter 3-Infectious Diseases Related to Travel- Japanese Encephalitis. Available at: (accessed 5 June 2018).

SPANZ.IMOJ.18.04.0141a - Date of preparation May 2018