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How and when is Japanese encephalitis spread?

Page last updated 03 April 2020


Japanese encephalitis (JE) is spread to humans 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. Australian Government, Department of Health. The Australian Immunisation Handbook. Japanese encephalitis. Available at: (accessed 10 March 2020).

2. NSW Government, Department of Health. Japanese encephalitis fact sheet. Available at; (accessed 10 March 2020).

8. Centers for Disease Control and Prevention. Japanese encephalitis – transmission. Available at: (accessed 10 March 2020).

9. Centers for Disease Control and Prevention. Chapter 4 – Travel-related infectious diseases - Japanese Encephalitis. Available at: (accessed 10 March 2020).

SPANZ.IMOJ.18.04.0141(1)a - Date of preparation March 2020