A 78-year-old Aboriginal woman from Perth has died after catching Murray Valley Encephalitis during a trip through northern Western Australia.

Health officials believe she was bitten by infected mosquitoes in the West Kimberley last month. She died on June 7.

Authorities have since warned people in the Kimberley and Pilbara after surveillance detected signs of the rare mosquito-borne virus in both regions.

WA Health managing scientist Dr Andrew Jardine said Murray Valley Encephalitis, known as MVE, was uncommon but could be life-threatening.

"The wet season in northern WA, and the period immediately after it, are the highest risk time for mosquito-borne virus activity," Dr Jardine said.

"We urge residents and visitors to the Pilbara and Kimberley to take extra care to avoid mosquito bites during this period of increased risk, which can extend into July.

"There is currently no vaccine for MVE. The only way to prevent infection is to avoid being bitten by mosquitoes."

WA Health urged people in high-risk areas to cover up with loose, light clothing, sleep under nets or in mosquito-proof tents, and use repellent on exposed skin.

It also advised people to use repellents containing DEET, picaridin or Oil of Lemon Eucalyptus, applying them evenly to all exposed skin and reapplying as directed.

The woman's death is the first recorded MVE case in WA this year, following three notifications in both 2025 and 2024.

Early symptoms can include fever, severe headache, drowsiness, dizziness, nausea, neck stiffness, confusion or difficulty speaking.

WA Health said anyone experiencing symptoms after being bitten by mosquitoes should seek medical care urgently.

In serious cases, the virus can cause seizures, coma, permanent brain damage or death.

Parents have also been urged to seek medical advice if they are concerned about young children, as fever may be the only early sign of infection.