23 February 2011

Health warning to avoid Mosquitoes

Residents and visitors of the Southern and Murrumbidgee areas of NSW are reminded to take extra precautions and protect themselves against mosquitoes following the detection of Murray Valley Encephalitis or MVE virus in parts of Victoria and border areas of NSW.

The disease has been detected in sentinel chickens in the Victorian towns of Mildura, Robinvale, Kerang and Barmah, but also in Tooleybuc in NSW, near Swan Hill.

The Acting Director of NSW Health Protection, Dr Michael Staff, said this is a timely reminder for all people to cover up and avoid mosquito bites.

“Recent flooding and warm weather increase exposure to mosquito borne viruses such as Ross River virus and Barmah Forest virus which are common in NSW and can cause illness with symptoms including tiredness, rash fever and sore swollen joints,” Dr Staff said.

Dr Staff said while MVE has not been detected in humans, mosquitoes are known to bite chickens and can infect them with viruses.  Sentinel chicken flocks act as a warning system for human infection by being regularly monitored for any viruses that mosquitoes might be transmitting.

“While Murray Valley Encephalitis or MVE is rare, and most people will not develop symptoms, it is still a serious mosquito-borne disease that can lead to permanent brain damage and may be fatal in severe cases,” Dr Staff warned.

In mild cases, symptoms of MVE include fever, headache, nausea and vomiting and muscle aches. In more severe cases symtoms can include neck stiffness, lethargy, delerium, tremors and coma in severe cases.  People with these symptoms should immediately seek medical assistance.

“In young children, fever might be the only early sign, so parents should see their doctor if concerned, and particularly if their child has convulsions, drowsiness, floppiness, irritability, poor feeding or general distress.”

“The MVE virus is transmitted by infected mosquitoes which breed in flooded, grassy and swamp areas and around rivers and waterways. The mosquito is especially active around dawn and around sundown, with a peak in the first two hours of the night.

Simple steps to avoid being bitten by mosquitoes:

• Avoid being bitten by mosquitoes. Mosquitoes that carry the virus are usually most active in the hours after sunset and again around dawn
• When outside cover up as much as possible with light-coloured, loose-fitting clothing and covered footwear.
• Use an effective repellent on all exposed skin. Re-apply repellent within a few hours, as protection wears off from perspiration, particularly on hot nights. The best mosquito repellents contain Diethyl Toluamide (DEET) or Picaridin.
• The stronger the concentration of an insect repellent, the less frequently it will need to be applied to stop mosquito bites. Repellents containing low concentrations of DEET or Picaridin provide shorter periods of protection and need to be reapplied more frequently so it's important to read the product information.
• Topical repellents are not recommended for use on children under 3 months. Use of physical barriers such as netting of prams, cots and play areas is preferred. Repellents containing less than 10% DEET or Picaridin are safe for older children if applied according instructions. Parents or carers should apply repellent.
• Light mosquito coils or use vapourising mats indoors. Devices that use light to attract and electrocute insects are not effective.
• Cover all windows, doors, chimneys, vents and other entrances with insect screens.
• Sleep under mosquito bed nets at night.
• When camping, use flyscreens on caravans and tents or sleep under mosquito nets.

There is no specific treatment for these viruses so prevention depends on avoiding mosquito bites, especially in the summer and autumn months when infections peak.

The last human case of MVE in NSW or Victoria was reported back in 1974 when a large outbreak occurred throughout much of south eastern Australia. The sentienial chickens were placed at locations along the Murray River region to act as an early warning system for possible human infections of this disease.

For a copy of the NSW Health fact sheet on Murray River Encephalitis (MVE) virus, Ross River Fever or Barmah Forest virus go to:

http://www.health.nsw.gov.au/factsheets/infectious/murray_valley_enceph.html

http://www.health.nsw.gov.au/factsheets/infectious/rossriver.html or http://www.health.nsw.gov.au/factsheets/infectious/barmah_forest_virus.html.