Doctors have described Victoria’s first reported case of Japanese encephalitis in an infant as Australia’s unprecedented outbreak of the mosquito-borne infection continues.  

The publication comes as experts warn next summer will likely reveal if the virus has become endemic and whether wider vaccination will be needed. 

The previously healthy four-month-old boy presented to hospital in February with febrile convulsions, two-day prodrome characterised by fever, and reduced energy and feeding, which progressed to aseptic meningoencephalitis.  

The team, from The Royal Children’s Hospital Melbourne, said their investigation turned up findings that were typical of Japanese encephalitis (JE) illness, including lymphocyte-predominant pleocytosis, diffuse EEG slowing and bilateral thalamic lesions on MRI scans.