Deadly mosquito virus on rise in Australia

AAP January 23, 2012, 2:21 pm

Cases of a deadly mosquito-borne virus increased dramatically in Australia last year, with further outbreaks possible this summer.

Three people died and there were 16 confirmed cases of Murray Valley encephalitis virus in 2011, according to an article in the Medical Journal of Australia.

There were no cases reported in 2010 and just four confirmed cases of the virus in 2009, data from the National Notifiable Diseases Surveillance System shows.

The virus is endemic in northern Australia but re-emerged in southeastern Australia last year, according to author Dr Jack Richards, of the Victorian Infectious Disease Service at Royal Melbourne Hospital, and his co-authors.

The increase in cases came in the wake of significant regional flooding, with deaths occurring in Western Australia, South Australia and the Northern Territory.

"The risk during this summer and the coming autumn remains uncertain, especially in areas that remain flooded," the report said.

"Recent circumstances remind us of the limited information we have about this disease, the challenges of clinical management and the need to prepare for future outbreaks."

The virus, which causes brain inflammation, is fatal in about 15 to 30 per cent of cases, with long-term neurological problems occurring in 30 to 50 per cent of survivors.

Just 40 per cent of sufferers make a complete recovery.

Symptoms include fever and headache, lethargy, confusion and sometimes seizures.

There is no cure and no vaccine.

The researchers said they are eagerly awaiting further trial data on interventions and the future development of effective antiviral agents.

In the meantime, prevention relies on the use of sentinel chicken flocks - whose sera are tested regularly to provide an early warning of virus activity - and on mosquito control.

People are advised to use insect repellents and wear long and loose clothing to help reduce mosquito bites.