Murray Valley Encephalitis alert

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Beware of mosquito bites

Health authorities are encouraging people in the Longreach local government area to beware of mosquito bites.

Central Queensland Public Health Unit Acting Director Dr Margaret Young said a recent public healthmosquito trapping program in the region had detected Murray Valley Encephalitis (MVE) in localmosquitoes on two separate occasions.

“MVE is an uncommon disease caused by the Murray Valley encephalitis virus,’’ she said.

“It is spread to humans through the bite of infected mosquitoes.

“No locally contracted human cases have been reported in Queensland since 2005 but the mosquitotrapping program shows the virus is still present.

“Most people with this infection remain completely well while others may only develop a mild illness withfever. But a small proportion of those infected develop a severe brain infection called encephalitis.

Dr Young said there was no vaccine against MVE.

“As with all mosquito-borne diseases, the best protection is to avoid being bitten and take action toeliminate potential mosquito breeding sites on your property,’’ she said.

“Personal protection includes wearing light-coloured, loose-fitting clothing with long sleeves and longtrousers, as well as using an effective insect repellent on any exposed skin.

“Using insecticide sprays or vapour dispensing units indoors or mosquito coils outdoors is anothereffective way to repel mosquitoes.

“You should apply residual pyrethroids around the home or campsite, and/or to nearby shrubbery thatprovide a harbourage for mosquitoes.

“Also, stay indoors when mosquitoes are most active, from just before sunset and all night.’’

Dr Young said many people who had lived for a long time in MVE affected areas would be protected(immune) because they had been exposed to the virus in the past.

But some people were more likely to develop MVE infections because they had not been exposed before.These included babies and young children, as well as people who were visiting or had recently moved toMVE affected areas.

Dr Young said symptoms of MVE usually appeared 5 to 28 days (average 14 days) after being bitten byan infected mosquito.

Early symptoms include: Headache Fever Nausea and vomiting Muscle aches.“Symptoms can progress to drowsiness, confusion, seizures, or fits, especially in young children,’’ DrYoung said.

“In very severe cases, these can progress to delirium, coma and death. Some who recover are left withongoing problems such as deafness or epilepsy.’’

Dr Young said the most important species of mosquito to carry the virus was the common bandedmosquito, Culex annulirostris.

“This mosquito is widespread throughout Australia and breeds in fresh water such as surface pools andnatural wetlands,’’ she said.

“The Culex annulirostris is a nocturnal mosquito most active in the early evening and pre-dawn periodand they have a flight range of several kilometres.

“Water birds, such as herons, are an important natural reservoir of MVE virus, allowing the virus tospread to new areas. Mosquitoes become infected by feeding on infected birds. An infected mosquitocan then bite a person and transmit the infection.’’Although MVE can occur throughout Australia, it is more common in the Top End of the NorthernTerritory and north-west of Western Australia.

But MVE also can occur in inland northern Queensland during some years.

The MVE virus is present during the wet and post-wet seasons from February to July, with most casesbeing reported between March and May.

During extensive wet seasons the range of viral activity mayextend to southern and south eastern regions.