Early detection of Murray Valley encephalitis virus activity in Victoria using mosquito surveillance

To the Editor: The flavivirus Murray Valley encephalitis virus (MVEV) was isolated in 1951 from the brain tissue of fatal cases of encephalitis.1 Subsequent work by Australian investigators established MVEV as the likely aetiological pathogen of the severe encephalitis “Australian X disease”.1 MVEV is enzootic in northern Western Australia and the Northern Territory, resulting in sporadic human cases.2 In south‐east Australia, however, MVEV activity can be absent for decades only to reappear with significant human outbreaks. The three most recent outbreaks in Australia were in 1951 (45 cases), 1974 (58 cases) and 2011 (17 cases).1,2,3 The case fatality rate is about 18% in hospitalised patients, reflecting the severity of disease.4