A deadly mosquito-borne virus that has no cure and no vaccination, has claimed the lives of two Australians.

Both the Murray Valley encephalitis (MVE) and the closely-related Kunjin viruses cause a serious inflammation of the brain, and have already hospitalised six West Australians. The Health Department is continuing to investigate reports that more people have been infected.

Two people have died this month from a deadly mosquito-borne virus.

Department entomologist Sue Harrington said while there was no suggestion the MVE virus would reach Perth, the fact it had already hit the Wheatbelt and mid-west regions was of a concern.

"It seems to have activated independently this season," she said.