A woman has died after contracting rare mosquito-borne virus Murray Valley encephalitis while travelling in WA’s north last month.

The WA Department of Health said the 78-year-old Aboriginal woman from Perth was exposed to infected mosquitoes while travelling in the West Kimberley region. She died on June 7.

On Wednesday, the Department issued an alert to the Kimberley and Pilbara regions after detecting Murray Valley encephalitis activity which suggested there was an ongoing risk.

WA Health managing scientist Dr Andrew Jardine described the virus as a rare but potentially fatal mosquito-borne illness.

“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.”

The case was the first in WA this year, and came after three MVE notifications in both 2025 and 2024.

Early symptoms included severe headache, difficulty speaking or confused speech as well as fever, drowsiness, neck stiffness, nausea, and dizziness.

WA Health has urged anyone experiencing those symptoms should seek medical care as soon as possible.

In more severe cases, individuals may experience seizures, fall into a coma, suffer permanent brain damage or die.

In young children a fever may be the only early sign of infection, and parents should seek medical advice if they are concerned, particularly if a child shows drowsiness, seizures, floppiness, irritability, poor feeding or general distress.

Precautions include wearing loose-fitting, light coloured clothing, using mosquito nets and mosquito-proof tents and applying 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.

Free mosquito repellent is provided in locations such as the Pilbara and Kimberley, where the risk of mosquito bites is highest, under the Repel, Prevent, Protect program which rolled out in 2025.