The first confirmed outbreak of Barmah Forest virus in Tasmania - 2019

To describe the first outbreak of Barmah Forest virus (BFv) in Tasmania and identify potential vectors for BFv in Tasmania.

A retrospective descriptive study of BFv notifications in the Tasmanian Notifiable Diseases Database (TNDD) was conducted. Adult mosquitoes were sampled from areas near outbreak cases and pooled samples were tested for BFv.

27 cases of confirmed BFv were recorded in the TNDD between 12 March 1999 and 30 June 2019. Nine cases were recorded between 21 January and 10 May 2019 that were acquired in Tasmania, with eight included in this confirmed outbreak. All outbreak cases resided in or travelled to locations in the Break O'Day Local Government Area and reported no recent interstate travel. No virus was detected in pooled mosquito samples.

This is Tasmania's first confirmed outbreak of BFv. Known BFv vector species were identified in both saltmarsh and urban-fringe brackish saltmarsh larval habitats. BFv was not detected from pooled mosquito samples.

Clinicians should consider BFv as a possible diagnosis for presentations with fever and arthritis, and potential mosquito exposure in Tasmania. These findings will guide broadening of prevention-focussed public health messaging.