14 July 2023

New Murray Valley encephalitis case prompts mosquito warning for the Kimberley

Please note: to respect the privacy of patients, no further identifying information will be provided.

A traveller is in a metropolitan hospital after being infected with Murray Valley encephalitis, as WA records its worst season for the virus in 12 years.

The Department of Health is urging residents and travellers in the Kimberley region to take extra precautions to prevent mosquito bites following unseasonal rainfall and ongoing human cases of the mosquito-borne Murray Valley encephalitis (MVE) in the region.

The warning follows the deaths of two people from Murray Valley encephalitis earlier this year. Four other people have also been infected in the Kimberley region in the last 12 months, with the most recent case in late June.

Department of Health Managing Scientist, Dr Jay Nicholson, said “recent unseasonal rainfall in the Kimberley has extended breeding conditions for mosquitoes in the region, increasing the risk of people being exposed to MVE virus and a range of other mosquito-borne viruses, including Japanese encephalitis virus.”

Virus activity continues to be detected in mosquitoes and sentinel chicken flocks in the Kimberley region. Sentinel chicken flocks are used by the Department of Health to provide an early warning system for mosquito-borne virus activity.

“Murray Valley encephalitis virus is transmitted by mosquitoes, and while the risk of being infected and becoming unwell is low, the illness caused by the virus can be severe and potentially fatal, as we have seen in two cases this year,” Dr Nicholson said.

Initial symptoms of MVE include fever, drowsiness, headache, stiff neck, nausea and dizziness. People experiencing these symptoms should seek medical advice as soon as possible. In severe cases, people may experience seizures, lapse into a coma, be left with permanent brain damage or die.

In young children, fever might be the only early sign of infection. Parents should see their doctor or local health service urgently if concerned, particularly if their child experiences drowsiness, floppiness, irritability, poor feeding, or general distress.

Dr Nicholson said there are no vaccines against MVE, and the only effective protection against infection is to take precautions to avoid mosquito bites. There is no need to change travel plans, but with the peak holiday season now in the Kimberley this is an important and timely reminder not to be complacent.

Protect yourself and your family from the risk of mosquito-borne diseases through the following measures to prevent mosquito bites:

  • avoid outdoor exposure to biting mosquitoes, particularly at dawn and early evening
  • wear protective (long, loose-fitting, light-coloured) clothing when outdoors
  • apply an effective personal mosquito repellent containing diethyltoluamide (DEET), picaridin or Oil of Lemon Eucalyptus (PMD/OLE) evenly to all areas of exposed skin and always follow the label instructions
  • ensure insect screens are installed and in good condition on houses and caravans
  • use mosquito nets and mosquito-proof tents if sleeping outside
  • use mosquito coils and mosquito lanterns and apply barrier sprays containing bifenthrin in patio and outdoor areas around houses
  • ensure infants and children are adequately protected against mosquito bites, preferably with suitable clothing, shoes/socks, bed nets or other forms of insect screening
  • keep grass/weeds and other vegetation short to stop mosquitoes seeking shelter and hiding around the home
  • remove water holding containers from around the home and garden to ensure mosquitoes do not breed in your own backyard

For more information about mosquito prevention visit:


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