Murray Valley encephalitis in Australia - Western Australia

On 31 March media reported the death of a child due to Murray Valley encephalitis (MVE). It is believed the child may have been exposed to an infected mosquito in the West Kimberly region, Western Australia. This case is only the second MVE case reported in Western Australia since 2008, although 8 MVE cases have been reported for Australia as a whole in 2023.

The recent major flooding in West Kimberly (in January 2023) have resulted in ideal mosquito breeding conditions which may have led to increased risk of MVE in the area. Local public health officials are advising mosquito bite protection measures.

Murray Valley encephalitis virus is transmitted by Culex mosquitoes and can cause fever, headache, nausea, rash, muscle and joint pains, rash and fatigue. More seriously, encephalitis occurs in some cases.

Advice for Travellers

MVE is rare but all travellers to outbreak areas are potentially at risk of infection. The risk is greatest for those:

• participating in outdoor activities during twilight hours
• travelling for a prolonged period of time
• frequently exposed to mosquito bites in rural infected areas (e.g. swamps, wetlands, parks)

All travellers should be advised on:

• the risks and potentially severe consequences of MVE
• practicing strict mosquito bite avoidance measures, including correct use of insect repellents
• minimising outdoor activities during twilight hours when Culex mosquitoes bite

Travellers at increased risk of developing severe clinical disease are those:

• with pre-existing chronic medical conditions
• younger than 10 years of age
• older than 50 years of age

No vaccine is available and there is no specific treatment.

For further information on how to reduce mosquito bites, see the Mosquito Bite Avoidance page.