Date Published: 23 March 2009
Murray Valley encephalitis risk intensifies in northern WA
The Department of Health has reiterated its warning to people living and holidaying in the northern half of WA to take extra care against mosquito bites, following a substantial increase in the activity of mosquito-borne viruses and a suspected case of Murray Valley encephalitis (MVE) in a Kimberley resident.
Senior Scientific Officer Susan Harrington said that the Department’s surveillance program (undertaken by The University of Western Australia) had now detected activity of the rare, but potentially fatal, MVE virus as far south as Carnarvon in the Gascoyne region for the first time this season.
This southern expansion of MVE activity is in addition to ongoing and intensifying activity of MVE virus across the Kimberley and Pilbara following the widespread rains in the north of WA over the past two months.
“MVE is a rare disease but can be very severe or fatal, so it is important that people living or travelling in WA take particular care to avoid mosquito bites for the next few weeks,” Ms Harrington said.
“Initial symptoms of MVE include fever, drowsiness, headache, stiff neck, nausea and dizziness and people experiencing these symptoms should seek medical advice quickly. In severe cases, people may experience fits, lapse into a coma, may be left with permanent brain damage or die.”
“In young children, fever might be the only early sign, so parents should see their doctor if concerned, and particularly if their child is drowsy, floppy, irritable, feeding poorly or is generally distressed.”
Ms Harrington said people most likely to be affected by the MVE virus were newcomers to affected regions, such as babies, young children, tourists or new employees, but anyone experiencing these symptoms should seek medical advice quickly.
“Wet season activity of other mosquito-borne viruses is also continuing in the north, with ongoing activity of Kunjin virus being detected, a mosquito-borne virus related to MVE, which can cause milder human disease. Over 40 cases of human infection with Ross River and Barmah Forest viruses have also been reported from the Kimberley and Pilbara in the past two months,” she said.
“There are no specific cures or vaccines for MVE, Kunjin, Ross River or Barmah Forest viruses so it is very important that people take care to prevent being bitten by mosquitoes.”
The warning particularly applies to people living, visiting or camping near swamp and river systems and rain affected areas during the evening and night through the Kimberley, Pilbara and Gascoyne regions.
However, the viruses may be active elsewhere in the north of the State, especially where mosquitoes are abundant.
Ms Harrington said controlling mosquitoes in most rural regions of WA was generally not possible because of the large size and inaccessibility of natural mosquito breeding habitat.
However, it was also important that communities prevent mosquitoes breeding in man-made sites around the home or workplace because these types of mosquitoes can also be disease carriers.
People do not need to alter their plans to visit the northern half of WA but it is important to avoid mosquito bites by taking a few simple steps, such as:
1. avoiding outdoor exposure from dusk and at night
2. wearing protective (long, loose-fitting) clothing when outdoors
3. using a personal repellent containing diethyl toluamide (DEET) or picaridin. The most effective and long-lasting formulations are lotions or gels. Most natural or organic repellents are not as effective as DEET or picaridin
4. ensuring insect screens are installed and completely mosquito-proof: use mosquito nets and mosquito-proof tents
5. ensuring infants and children are adequately protected against mosquito bites, preferably with suitable clothing, bed nets or other forms of insect screening.