The Tasmanian health department has warned people on the state's east coast to protect themselves against mosquito bites after two cases of an unusual virus.

Two cases of a debilitating mosquito-borne virus have been detected in Tasmania, prompting a warning to residents and travellers on the state's east coast.

Another three potential cases of the Barmah Forest virus, spread by mosquitoes, are being investigated by the state's health department.

"This is unusual. These may be the first diagnosed cases of this virus caught in Tasmania," Public Health Services Clinical Director Dr Faline Howes said on Friday.

Barmah Forest is similar but less severe than Ross River virus and symptoms, including joint pain, tiredness, headaches and muscle pain, can last for months.

Health authorities are urging people on Tasmania's east coast to protect themselves against mosquito bites.

All five cases relate to people who live or have travelled on the east coast.