A Victorian man has been found to have died from the mosquito-borne virus Japanese encephalitis (JEV), the Victorian Department of Health has revealed.

The announcement comes after Australia's acting chief medical officer declared a national alert about the spread of JEV in multiple states on Friday.

The Victorian man, who was from the state's north and was aged in his 60s, died on February 28, according to health authorities.

READ MORE: National alert declared amid fears of Japanese encephalitis virus spread

An autopsy has since revealed JEV was the case of his death, with investigations into how he contracted the virus now underway.

The man's death is the first JEV death in the state, while seven cases have been found in the state this year.

JEV is spread through the bite of an infected mosquito.

The virus also infects pigs and horses.

Most humans who contract the virus do not experience any symptoms, or mild symptoms like headaches or fever.

A person with severe disease may suffer inflammation of the brain, sudden onset of vomiting, high fever and chills, severe headaches, sensitivity to light, neck stiffness and nausea.

READ MORE: Two in hospital as mosquito-borne disease spreads in NSW

Japanese encephalitis cannot be spread from person to person.

The Department of Health is strongly advising people limit their exposure to mosquitoes and avoid mosquito habitats such as stagnant water.

The department has warned mosquito numbers are high in many parts of northern Victoria, and that people with increased exposure to mosquitoes may be at a higher risk of infection, particularly people working or living on pig farms, or working or spending time outdoors.

A Japanese encephalitis vaccine is available and is recommended for people who work with or around pigs.

Two New South Wales residents are seriously ill in hospital with the virus, while the virus has also been detected in Queensland.