A cluster of Brucella melitensis in Melbourne, Australia 2023: clinical and public health actions

Abstract: Brucellosis is a rare zoonotic infection most commonly seen in parts of the Northern Hemisphere. Infections in Australia are uncommon and occur predominantly in Queensland and New South Wales due to the association with wild pig hunting activities. We describe a clustering of two cases of brucellosis in Victoria confirmed by genomic analysis but with no identified exposure. We detail the medical management, laboratory confirmation, and the public health investigation. While the source of the outbreak remains unclear, the two cases demonstrate a detailed and coordinated public health response to a rare infection with a unique geographical and temporal relationship.