06 April 2023

Communities in regional NSW are again being urged to protect themselves against mosquito bites this Easter holiday period following confirmation of two further cases of Murray Valley encephalitis (MVE) virus infection in NSW.

These two latest cases are in addition to MVE cases previously identified in February and March, bringing the total number of cases to four for the season. MVE cases have also recently been identified in border communities in Victoria, including among people who may have exposures in NSW.

The virus has been detected in a man in his 20s from Federation LGA, who was infected between mid-February and early March 2023. He was most likely exposed to the virus either while at work in Federation Shire, or while camping in Indigo Shire in Victoria. He remains admitted to hospital.

The virus has been detected in a man in his 60s from Leeton Shire LGA, who was infected in March 2023 and was most likely exposed to the virus around home and his local area. He remains admitted to hospital.

Keira Glasgow, Director of NSW Health's One Health branch, said the latest cases are a timely reminder for communities around the NSW and Victorian border to take action to protect themselves against mosquito bites.

"There is no vaccination or specific treatment for Murray Valley encephalitis, so we are urging the community to do everything they can to protect themselves against mosquito bites," Ms Glasgow said.

“We have now identified four cases of MVE and the number of MVE detections through surveillance of mosquitoes and sentinel chickens in NSW this season is concerning. With many families spending time camping or enjoying the outdoors this coming weekend, we are urging people to avoid mosquito bites.

"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, Kunjin and Barmah Forest viruses.

"Only a small proportion of people infected with Murray Valley Encephalitis virus will have any symptoms, which include fever, headache, nausea, vomiting, loss of appetite, diarrhoea, and muscle aches.

"Signs of severe infection include severe headache, neck stiffness, sensitivity to bright lights, drowsiness, confusion, seizures, and loss of consciousness.”

MVE virus is spread to humans by infected mosquitoes. Rarely, it causes severe neurological illness. The primary hosts of MVE and Japanese encephalitis virus (JEV) are wild waterbirds such as herons and egrets.

Protect yourself and your family from mosquito bites by:

  • wearing light, loose-fitting long-sleeved shirts, long pants and covered footwear and socks, especially around dusk and dawn
  • applying repellent to all areas of exposed skin, using repellents that contain DEET, picaridin, or oil of lemon eucalyptus
  • re-applying repellent regularly, particularly after swimming, being sure to always apply sunscreen first and then apply repellent
  • covering openings such as windows and doors with insect screens and checking there are no gaps in them
  • removing items that might collect water (such as old tyres, empty pots) outside your house where mosquitoes can breed
  • improving drainage on your property so that water does not become stagnant
  • using insecticide sprays, vapour dispensing units and mosquito coils to repel mosquitoes (mosquito coils should only be used outside).

NSW Health has established an expert advisory panel on mosquito control and management with medical entomologists from across Australia. This panel will look closely at the various approaches to mosquito control in different environments and in areas with different population densities to help inform the approach to mosquito control and management in NSW.

For more information visit Mosquito-borne diseases.