Recent detections of Japanese encephalitis virus (JEV) have been reported in southern Queensland, with cases confirmed in humans, mosquitoes, and pigs.

Healthcare professionals are encouraged to promote JEV prevention measures to at risk groups, and consider JEV infection in patients presenting with encephalitis, particularly those reporting recent outdoor activity, mosquito exposure or proximity to pigs in areas where JEV has been detected.

Key Points

• Consider the diagnosis of Japanese Encephalitis (JE) in patients with a clinically compatible illness and exposure risk factors, or in the absence of other causes for meningoencephalitis.

• Discuss any suspected cases of JEV infection with your local public health unit, infectious diseases physician or clinical microbiologist.

• Promote mosquito-bite avoidance – using repellents containing DEET, picaridin or oil of lemon eucalyptus and wearing long loose-fitting clothing, ensuring insect screens are functional and avoiding areas of high mosquito activity at dawn and dusk.

• JEV vaccination is recommended and funded for certain at-risk groups.

Signs and Symptoms

• Almost all people (about 99%) infected with JEV experience no symptoms or only mild symptoms, such as fever and headache.
• Severe disease is characterised by an acute encephalitis, with sudden onset of high fever and chills, severe headache, photophobia, neck stiffness, nausea, vomiting, convulsions, and coma. Of these severe cases, approximately one-third die, and one-third are left with permanent neurological sequalae.

Transmission

• JEV can only be spread by the bite of an infected mosquito, with development of symptoms usually occurring 5 to 15 days later.
• JEV does not spread directly between humans or from infected animals to humans.
• There is no risk from consuming pork or pork products.

Prevention

Encouraging patients to adopt personal protection measures to prevent being bitten by mosquitoes can reduce the risk of JEV exposure. These include:

• Avoiding mosquitoes when they are most active, particularly at dusk and dawn.
• Covering up with light-coloured, loose-fitting clothing with long sleeves, long trousers, socks, and covered footwear when outside.
  • Apply an effective insect repellent on exposed skin and reapplying within a few hours, following the manufacturer's instructions. The best repellents contain DEET, picaridin or oil of lemon eucalyptus.
  • Using insecticide sprays, vapour dispensing units (indoors), or mosquito coils (outdoors) to repel or kill mosquitoes.
  • Ensuring flyscreens in your home, tent or caravan are in good condition so mosquitoes cannot enter.
  • Using mosquito-proof tents when camping.

Vaccination

JEV vaccination is recommended and funded for:

• Individuals who live, work, or plan to visit specific local government areas (LGAs) and are at risk of mosquito bites.
• Individuals who live near, work at, or plan to visit a piggery or pork abattoir.
• Individuals at risk through occupational or recreational activities that bring them in contact with mosquitoes or pigs.
• For detailed eligibility criteria visit the Queensland Health Japanese Encephalitis conditions website.
• Travel vaccination is also recommended, but not funded, for people travelling to Asia or Papua New Guinea.
• Access the JEV vaccination centre finder to locate JEV vaccine service providers in your area.
• Vaccine service providers can register and order funded JEV vaccine by contacting  QHIP-ADMIN@health.qld.gov.au.

Further information

Japanese encephalitis virus fact sheet | Queensland Health
Japanese encephalitis | The Australian Immunisation Handbook (health.gov.au)
Public health units | Queensland Health

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