WA Health confirms first Murray Valley encephalitis case for 2025

The following media release has been issued by the Department of Health.

WA Health is warning the community to protect themselves against mosquito bites as Western Australia has recorded its first confirmed case of Murray Valley encephalitis (MVE) for this wet season. 
 
The case was identified in a child who acquired the infection in the east Kimberley region and is currently receiving medical care. 

Managing Scientist Dr Andrew Jardine said that MVE was a rare but serious mosquito-borne disease. 

In 2024, WA recorded four cases, with two resulting in death. Significant flavivirus activity, including MVE virus, continues to be detected in sentinel chicken flocks across the Kimberley and Pilbara regions, indicating ongoing risk in northern WA.

Dr Jardine said the northern wet season, and the period immediately following it, are the highest risk periods for mosquito-borne disease activity in northern WA and urged the public to take warnings seriously.

“MVE can cause severe illness, including brain inflammation, coma, permanent brain damage and, in some cases, death,” Dr Jardine said.

“Preventing mosquito bites is the best way to stay protected against potentially serious infections like MVE and other dangerous mosquito-borne viruses such as Japanese encephalitis virus and Kunjin virus.”

Early symptoms of MVE may include fever, drowsiness, headache, stiff neck, nausea, and dizziness, which may progress to confusion, weakness, vision or speech problems or seizures. Symptoms in young children may include drowsiness, floppiness or general distress. In infants, fever might be the only early sign of infection. Seek urgent medical attention if you or your child experience any of these symptoms.

Appropriate steps to protect against mosquitoes is available via HealthyWA, and includes: 

Cover up: 

• Avoid being outdoors at dawn and early evening when mosquitoes are most active.
• Wear long, loose fitting, light-coloured clothing.
• Dress babies and children in suitable clothing, including socks/shoes, and use bed/pram netting.
• Ensure insect screens are installed and in good condition on houses and caravans.
• Use mosquito nets and mosquito-proof tents if sleeping outside.

Repel:

• Apply an effective personal mosquito repellent containing diethyltoluamide (DEET), picaridin or Oil of Lemon Eucalyptus (also known as PMD) evenly to all areas of exposed skin and always follow the label instructions.

Clean up:

• Keep grass and other vegetation short to help prevent mosquitoes around your home.
• Empty or remove water holding containers around your home.

For more information on MVE, including prevention, visit: Murray Valley encephalitis and Kunjin viruses.