Murray Valley encephalitis (MVE) virus has been detected in mosquitoes in northern Victoria this mosquito season which marks the first detection of the virus in Victoria in over 10 years through surveillance programs.
The last human cases of MVE virus infection in Victoria were reported in 1974 following significant flooding. Human cases were reported in New South Wales and South Australia in 2011.
The best prevention is to protect against mosquito bites:
- Cover up – wear long, loose-fitting, light-coloured clothing.
- Use mosquito repellents containing picaridin or DEET on all exposed skin.
- Limit outdoor activity if lots of mosquitoes are about.
- Remove stagnant water where mosquitoes can breed around your home or campsite.
- On holidays make sure your accommodation is fitted with mosquito netting or screens.
- Use ‘knockdown’ fly sprays and plug-in repellent devices indoors.
- Don’t forget the kids – always check the insect repellent label. On babies, you might need to spray or rub repellent on their clothes instead of their skin. Avoid applying repellent to the hands of babies or young children.
- Sleep under mosquito nets treated with insecticides if you don’t have insect screens on windows on your home or are sleeping in an untreated tent or out in the open.
- Mosquito coils can be effective in small outdoor areas where you gather to sit or eat.
The risk of mosquito-borne diseases, such as MVE, Japanese encephalitis, Kunjin/West Nile Virus, and Ross River and Barmah Forest virus infections, is high due to recent weather conditions and elevated mosquito numbers across Victoria.
Most mosquito bites do not transmit infection but anyone is potentially at risk of mosquito bites and mosquito-borne diseases. People who work, live or spend time outdoors in rural or regional Victoria, particularly inland riverine regions and extending up towards the Murray River, have a higher risk of exposure to mosquitos.
Most people infected with MVE virus do not have symptoms. Less than one per cent of people develop clinical disease. If symptoms develop, they typically start seven to 12 days after exposure but may occur anywhere from five to 28 days after exposure.
People with symptoms of MVE virus infection should seek urgent medical care. Symptoms include fever, headache, nausea, vomiting and muscle aches. In rare cases, people can develop meningitis or encephalitis and have symptoms of severe headache, neck stiffness, sensitivity to bright lights, drowsiness, confusion, seizures, loss of consciousness or coma. Serious illness can result in death or long-term neurological complications.
People who have been exposed to MVE virus are likely to have long-lasting immunity to subsequent infections.
