A third death has been confirmed in Australia’s outbreak of Japanese encephalitis, as an international expert warns that only “a higher power” can eliminate the virus from Australia.

The SA patient, reported to have died from an unknown suspected mosquito-borne virus in February, has been posthumously confirmed as a Japanese encephalitis virus (JEV) case, the state’s Department for Health and Wellbeing said on Friday.

SA has now confirmed eight cases of Japanese encephalitis in total — including five still in hospital — taking the national figure to 25 across SA, NSW, Victoria and Queensland.

UK neurologist and emerging diseases expert Professor Tom Solomon told an Australian webinar on Thursday night he would be surprised if the country could eliminate the virus given the numbers.