Japanese encephalitis has been detected at four more Victorian piggeries.

Agriculture Victoria on Tuesday confirmed the mosquito-borne virus had been detected in the regional local government areas of Campaspe, Loddon, Gannawarra and the Northern Grampians.

There are now 10 confirmed detections of the Japanese encephalitis virus at piggeries across the state.

Agriculture Victoria said it was working closely with the health department to reduce the risk of human exposure.

Australia has had 18 confirmed cases of JEV in humans: six in NSW, seven in Victoria, four in SA and one in Queensland.

Two of those cases have been fatal, with one fatality in NSW and another in Victoria.

Japanese encephalitis is transmitted via mosquitoes and cannot be spread from person to person or by eating animal products.

About 99 per cent of cases are asymptomatic but some people may experience fever and headache, while one per cent could experience severe infection including convulsions, paralysis, neck stiffness, tremors and coma.

Children aged under five and the elderly are more likely to develop severe infection.