A 27-year-old South Australian man has died from Murray Valley Encephalitis (MVE).
SA Health's chief medical officer Paddy Phillips said the man had been receiving hospital care for MVE since March.
"Two confirmed cases of MVE have been reported in South Australia this year, the first reported cases of locally-acquired MVE since 1974," Professor Phillips said in a statement.
"It is with deep sadness that we announce that one of the people who contracted MVE has died."
There is no specific treatment or vaccine to protect against the disease which is spread via mosquito bites but is not transmitted from person to person.
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Most people have only mild symptoms, including fever, headache, nausea and vomiting.
But in about one in 1000 cases, symptoms can worsen, with increasing confusion, headaches, drowsiness, neck stiffness, tremors and seizures.
The other confirmed case of locally-acquired MVE involved a 47-year-old man, who has since been discharged from hospital.
MVE has also recently been detected in Victoria and NSW.
"SA Health continue to work with local councils on mosquito control programs but the best protection against MVE and other mosquito borne diseases remains not getting bitten by mosquitoes," Professor Phillips said.
