CASE NOTES
A novel outbreak of Brucella suis in a veterinary practice: a One Health investigation
Cecily Moore and Emily Gibson
Posted Flock and Herd August 2025
In January 2025, an outbreak of brucellosis was identified by the Hunter New England Public Health Unit (HNEPHU) at a veterinary practice following notification of several cases amongst staff, the first known outbreak of this nature in Australia. Active case finding revealed further cases. Typing confirmed B. suis in a subset of cases.
In Australia, B. suis affects feral pigs (after being eradicated from the Australian domestic pig population), pig-hunting dogs and uncommonly humans (usually involved in pig hunting). In humans, the clinical presentation is variable but may include a flu-like illness characterised by fever, headache, weakness and generalised body aches. There is a risk of severe complications and undulating illness.
A comprehensive One Health approach was taken during this investigation. The HNEPHU worked with counterparts in animal health, clinical infectious diseases, and veterinary and human health laboratories.
An expert panel included these partners and colleagues with specific national brucella experts providing guidance to the investigation and interpretation of findings. A site visit was conducted by HNEPHU and LLS with a detailed inspection of the clinic that included environmental sampling, a serosurvey and a questionnaire for all staff. Cases were reviewed by the John Hunter Infectious Diseases Team. Laboratory investigations included serology and cultures for staff willing to be tested, followed by whole genome sequencing (WGS) for positive cultures. WGS indicated a single exposure event. Environmental samples from the clinic were tested by EMAI and revealed multiple positive PCR brucella results.
To explore the source of the outbreak, high-risk procedures in pig-hunting dogs were cross matched with staff rosters. This process was complicated by data quality issues and the euthanasia and disposal of dogs identified for testing. At the time of writing investigations were ongoing, with findings and learnings included in the presentation.