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Japanese encephalitis virus situation declared a Communicable Disease Incident of National Significance

March 28, 2022

Australia’s Acting Chief Medical Officer, Dr Sonya Bennett, has declared the unfolding situation in Australia concerning the Japanese encephalitis virus (JEV) a Communicable Disease Incident of National Significance.

The declaration was made under the Emergency Response Plan for Communicable Disease Incidents of National Significance, in consultation with the Australian Health Protection Principal Committee.

Read the press release

Queensland Government Department of Health have summarised key points and provided the following information:

KEY POINTS

  • JEV has been declared a Communicable Disease Incident of National Significance following detections of JEV in humans and piggeries in Queensland, New South Wales, Victoria, and South Australia.
  • JE should be considered in patients presenting with clinical features suggestive of viral meningoencephalitis with exposure risk factors. These patients should be urgently directed to the local Emergency Department.
  • JEV infection is preventable through mosquito control measures and vaccination. Education for patients is encouraged to adopt personal protective measures.
  • Vaccination is currently only recommended for certain at-risk groups with further planning underway for vaccine distribution.

Risk factors

Local infection risks should be considered among:

  • People living on, or working at a piggery, particularly in regions where JEV has been detected.
  • People who engage in outdoor activities (e.g., camping, fishing, hiking) near significant mosquito populations, including waterways.
  • People in proximity with wild pig populations.

Humans are considered ‘dead-end hosts’ for JEV. Infection in humans does not result in sufficient viraemia to maintain autologous transmission cycles with the mosquito vector.

There is no risk from consuming pork or pork products.

Signs and Symptoms

  • Symptoms usually occur 5 to 15 days after a bite from an infected mosquito.
  • Most people infected with JEV are either asymptomatic or have only mild symptoms.
  • Severe disease occurs in approximately 1% of infections and is characterised by acute encephalitis with sudden onset of high fever and chills, severe headache, neck stiffness, disorientation, tremors, paralysis, convulsions, and coma.

Testing in the primary care setting

  • Routine testing of patients with undifferentiated viral illness for JEV in primary care is not recommended.
  • Patients who have recovered from viral meningoencephalitis may require testing in primary care for flavivirus antibodies on convalescent serum collected 3 to 4 week. after symptom onset. Indicate on the request form that you are considering a diagnosis of JEV and ask for paired testing if stored serum is available.
  • Seropositivity with cross-reactivity may be seen in persons that have been infected with other flaviviruses or that have received vaccination against flaviviruses. Discuss further with a clinical microbiologist, as needed.

Management

  • There is no specific treatment for patients with JEV infection
  • Treatment of patients with meningoencephalitis is supportive aimed at controlling intracranial pressure, maintaining cerebral perfusion, and preventing other complications.

Prevention

  • JEV infection is preventable through mosquito control measures and vaccination. Further information for consumers is available here: What is mosquito-borne Japanese encephalitis? | Queensland Health
  • Currently, the vaccination response is prioritising those at greatest risk for JEV infection, such as workers at piggeries where JEV has been detected.
  • As the situation evolves, Queensland Health will continue to work with the Australian Government Department of Health as well as the Department of Agriculture and Fisheries to discuss the role and prioritisation of vaccination as part of the national response. For detailed information see Japanese encephalitis virus (JEV) vaccines | Australian Government Department of Health
  • If you have any questions or concerns, please contact your local public health unit Public health units | Queensland

Further information

Japanese encephalitis virus (JEV) | Australian Government Department of Health
Japanese encephalitis virus fact sheet | Queensland Health
Japanese encephalitis | Australian Government Department of Health
Japanese encephalitis | The Australian Immunisation Handbook (health.gov.au)