Barmah Forest virus is a mosquito-borne alphavirus endemic in Australia.

The symptoms of Barmah Forest virus infection are very similar and clinically indistinguishable from those caused by infection with the other alphavirus endemic to Australia, Ross River virus, though symptoms are often less severe and of shorter duration.

Infection is most likely in the summer and autumn. The incubation period for this infection is about 7 days. Patients then present with fever, a maculopapular rash (other rashes have also been described), lethargy, and arthralgias. Some patients may have true arthritis. Other associated symptoms may include lymphadenopathy and headaches. Symptoms typically last 2-10 days, but a minority of patients may report arthralgias for weeks to months.