Japanese encephalitis - Information for health professionals

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Japanese encephalitis virus (JEV) is transmitted to humans and other animals by the bite of infected mosquitoes. Pigs are important in JEV transmission because pigs develop high levels of viremia sufficient to infect mosquitoes (amplifying host). 

Vaccination

There are two safe and effective vaccines for JE:

  • Imojev: Live attenuated vaccine given by subcutaneous injection. Primary course is one dose. Registered for use for all immunocompetent people aged ≥9 months, and non-pregnant people. Imojev is the preferred vaccine for all eligible immunocompetent people. 
  • JEspect / Ixiaro: Inactivated Japanese encephalitis vaccine given by intramuscular injection. Primary course is two doses. Available for use in infants and children aged ≥2 months, immunocompromised people, and pregnant people. Order limits apply- in NSW, JEspect is reserved for immunocompromised and pregnant people only. ​

A JEV vaccine is available for free for people who are at higher risk of catching the virus. 

Learn who is recommended to be vaccinated against Japanese encephalitis. 

​​JEV booster vaccination is recommended for some people at-risk of JEV, 1-2 years after they were last fully vaccinated.   

For more information, see the Australian Immunisation Handbook.

Approach to vaccination in NSW

NSW Health continually reviews the evidence related to JEV risk in NSW in consultation with a range of health and environmental experts.

Vaccine doses can be ordered through the State Vaccine Centre. For large volume orders, please contact the local public health unit.  

Patient investigation

Symptoms of JE include:

  • fever and headache, variably accompanied by 
    • ​neck stiffness
    • disorientation
    • nausea or vomiting
    • tremors
    • coma
    • seizures or convulsions
    • paralysis. 

​If patients present with symptoms of encephalitis, include JE in your differential diagnosis if they live or have visited rural areas, especially if they were near pig farms or report being bitten by mosquitos.

Refer patients with suspected JE to hospital for management and further investigation.

Health provider updates


Current as at: Thursday 4 December 2025
Contact page owner: One Health