department of
health and community services

media release

Mosquito-borne disease warning for the Top End

Wednesday 19 March 2008

The NT Department of Health and Community Services warns Top Enders to cover up and protect themselves from a potentially fatal mosquito-borne disease, Murray Valley encephalitis, following recent heavy rains.

Murray Valley encephalitis virus disease and other mosquito borne diseases such as Kunjin virus disease, Ross River virus disease, and Barmah Forest virus disease will be more prevalent during the Easter period and throughout April.

These viruses are transmitted by the bite of the common banded mosquito, which is likely to breed in high numbers across the Top End – including the Katherine region.

The warning particularly applies to people visiting, camping or living in rural areas or parks in the Top End and north-west WA within five kilometres of wetlands or river and creek systems over the Easter weekend.

Risk is highest at night near seasonal and temporary wetlands, coastal brackish swamps, billabongs, river floodplains and heavily vegetated dams and drains.

There is no need to avoid travel to the wetland risk regions if normal mosquito self-protection is observed.

Senior Medical Entomologist Peter Whelan says the period between March and June is historically the peak period for these viruses and precautions should be taken until the end of July when virus activity is expected to return to a minimum.

“Murray Valley encephalitis virus and the related Kunjin virus are both very active in the Top End over this period. While the NT sentinel chickens have not yet shown evidence of activity of these viruses, recent evidence of MVE positive sentinel chickens in the northwest of Western Australia indicates the potential start of the mosquito-borne Kunjin and Murray Valley encephalitis virus activity in the Top End of the NT.

“Usual symptoms of Murray Valley encephalitis virus disease include severe headache, high fever, drowsiness, tremor and seizures - especially in young children - and in some cases the condition progresses to delirium and coma, leading to paralysis or brain damage, with a 25 per cent mortality rate. Kunjin virus disease causes a milder disease, with fever and severe headache. People experiencing the early symptoms of both diseases should seek urgent medical attention.

Only about one person in 1000 who get bitten by Murray Valley encephalitis virus infected mosquitoes will contract the disease, with an average of one to two human cases of in the NT each year.

People most at risk of Murray Valley encephalitis disease are those with no prior exposure to it, including babies, young children, tourists or people from southern Australia. Long-term residents are, however, also at risk.

Precautions against being bitten by mosquitoes include:
· Avoid outdoor exposure from dusk and at night in risk areas and all areas of high mosquito activity.

• Ensure all insect screens are installed and mosquito proof. Use mosquito nets and mosquito-proof tents at night in all areas when camping or in unscreened areas
• Wear protective, light-coloured clothing with long sleeves, long trousers and socks between dusk and dawn.
• Use a protective repellent containing di-ethyl toluamide (DEET) or picaridin as a supplement to protective clothing when outdoors at night in areas of mosquito activity, or when mosquitoes are active in the day. The most effective and long-lasting formulations are those in lotions or gels. Most natural or organic repellents are not as effective as DEET or picaridin.
• Protect children against mosquito bites.
• Empty all receptacles that collect rain water to ensure they’re unsuitable for mosquito breeding.
  

Media Contact:
Cameron Jackson, DHCS Media Liaison Officer 0401 116 144