Victorians living or holidaying in northern parts of the state are being warned of a current and active risk of contracting Murray Valley encephalitis, following further detections of this virus in trapped mosquitoes in additional locations.
Murray Valley encephalitis has been detected in the local government areas of Loddon, Indigo and Mildura.
This follows detections reported last week in Bendigo and Mildura — which were the first detections of Murray Valley encephalitis in more than 10 years through mosquito-surveillance programs.
“While there are currently no cases in humans, these detections mean there is an imminent risk to human health, so we are urging people in northern Victoria to take immediate steps to reduce their exposure to mosquitoes,” Victoria’s Deputy Chief Health Officer Associate Professor Deborah Friedman said yesterday.
“Avoid being outdoors, especially at dusk and dawn, cover up with light-coloured, long-sleeved, loose-fitting clothing, regularly apply insect repellent, and get rid of water that mosquitoes breed in around your home.”
Most people infected with Murray Valley encephalitis do not have symptoms. However, in a small number of people, a life-threatening infection can result.
If symptoms develop, they typically start seven to 12 days after exposure, but may occur anywhere from five to 28 days after exposure.
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. There is no vaccine currently available for Murray Valley encephalitis virus.
It follows the detection of Murray Valley encephalitis in a mosquito in Menindee, NSW last Wednesday.
The NSW Department of Health encouraged communities across the state to take measures to protect themselves against mosquito bites.
The Murray Valley encephalitis virus is spread by mosquitoes from infected animals to humans.
Rarely, it causes severe neurological illness with headache, convulsions and reduced consciousness in some cases.
The virus cannot be transmitted between humans, and people cannot get the virus by touching an infected animal or eating animal products.
The primary hosts of Murray Valley encephalitis virus are waterbirds, such as herons and egrets.
The NSW Department of Health said the cases were likely related to recent rainfall and flooding.
Health Protection NSW executive director Richard Broome said most people who were infected with the virus that causes Murray Valley encephalitis do not have any symptoms.
“Only a small proportion of people infected with the virus will experience symptoms, which include fever, headache, nausea, vomiting, loss of appetite, diarrhoea, and muscle aches,” Dr Broome said.
“Among those who get a severe infection, some may die or have lifelong neurological complications.
“There is no vaccination or specific treatment for Murray Valley encephalitis and the best way to avoid infection is to avoid being bitten by mosquitoes, which are most active between dusk and dawn.
“Avoiding mosquito bites will also protect against other mosquito-borne infections including Japanese encephalitis, Ross River Fever and Barmah Forest virus.”
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