Top End residents are being urged to take care to protect themselves against mosquitoes because the Wet Season may cause a record number of cases of Ross River virus (RRV) and Barmah Forest virus (BFV).
The warning comes as seasonal rains and high tides have combined to threaten an increase in salt marsh mosquito numbers around the coastal Top End. The increased numbers are expected for about the next two weeks.
"Last year between July and November we recorded 54 cases of RRV in the Darwin urban area, which was the highest in 14 years. During the same period this year we've recorded 75 cases," said Department of Health and Families (DHF) Centre for Disease Control Director Dr Vicki Krause.
"If the trend continues in Darwin and in other Top End areas, we could see a record number of people contracting RRV or BFV this Wet Season.
"The likelihood of transmission at this time of the year is high, and usually increases in January and February with the advent of the freshwater breeding common banded mosquito, with rural areas facing the highest disease risk.
"High rainfall will also trigger the container-breeding mosquitoes at residential properties. The mosquitoes are capable of transmitting RRV.
"They will breed in roof gutters, pot plant drip trays, used tyres, buckets and other items that can collect water-even large fallen palm frond bases.
"Make sure the gutters on your roof are free-draining and check your yard for any container that can hold water. Tip the water out and store containers under cover to prevent potential mosquito problems," Dr Krause added.
People infected with RRV or BFV may develop a wide range of unpleasant symptoms, including painful or swollen joints, particularly in the hands, ankles and knees.
Sore muscles, aching tendons, skin rash, fatigue, fever, headache and swollen lymph nodes are other signs of the illnesses. Symptoms can last for a few weeks, although some people experience sickness for up to a year.
Protection against bites is the best course of action as there is no vaccine to prevent either RRV or BHV.
Page 1 of 2
The salt marsh mosquito, Aedes vigilax, is prevalent from the late Dry Season to the early Wet Season, while the common banded mosquito, Culex annulirostris, is prevalent from the early Wet Season to the early Dry Season. Both are capable of infecting people with BBV and BFV.
High numbers of salt marsh mosquitoes are expected for about the next ten to fourteen days. Areas that may be affected include Darwin's northern suburbs of Leanyer, Malak, Karama, Brinkin, Tiwi and Lyons, as well as non-residential areas including Lee Point, Buffalo Creek, Casuarina Coastal Reserve, Holmes Jungle and the Leanyer shooting range.
Palmerston areas nearest to Mitchell Creek, Brookings Creek, and Hudson Creek will also be affected, as well as rural residential areas including those nearest to Noogoo, Millner, and Howard swamps, which include Knuckey's Lagoon, Robertson Barracks and Howard Springs.
The remainder of the NT coast can expect increased mosquito numbers within 5 km of brackish swamps and tidal creeks, including those near the tidal floodplain areas of the Daly, Adelaide, Mary, Alligator and Roper rivers. Mosquitoes may also be a problem within 30 km of the large tidal floodplains of major rivers.
Top End mosquito protection fact check
Avoid locations near rivers, coastal floodplains and swamps, and mangroves in the evening and night, unless taking protective measures against mosquitoes
Avoid outdoor exposure around dusk and at night near extensive mosquito breeding areas and during times of high mosquito activity
Use mosquito-proof accommodation and camping facilities at night in mosquito prone areas
In areas where mosquito bites are likely, wear light-coloured clothing with long sleeves, long trousers, and ankle protection with socks between dusk and dawn
Use a protective repellent containing 20% DEET or picaridin
Ensure that children are adequately protected against mosquito bites
More information: www.health.nt.gov.au/Medical_Entomology
Release date: 15 December 2009
