Buruli ulcer (BU) endemicity is changing in Victoria, Australia. This study describes the emergence of BU cases in urban Geelong and examines timing and proximity of human cases to environmental Mycobacterium ulcerans DNA detection in possum faeces. From 2011-2022, 80 BU cases were reported, with clusters emerging in new endemic areas from 2019 onwards. Temporal analysis revealed cases occurred near M. ulcerans positive possum faeces, that preceded human cases by up to 39 months. Median diagnosis delay in these emerging areas was 7 weeks, longer than in established BU endemic areas. The findings emphasise the geographic and temporal association between BU emergence and possum faecal M. ulcerans presence, suggesting monitoring possum faeces as a viable early warning sign of increased BU risk in such areas. This proactive approach can enable early action to improve clinician and community BU awareness, or development of innovative control strategies, to reduce disease burden.

The authors have declared no competing interest.

The data collection and analysis of the possum faecal surveys were funded as part of the NHMRC Partnership Project Grant 2018-2020 (GNT1152807).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Barwon Health Human Research Ethics Committee gave ethical approval for this work.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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Sharing of de-identified human case data used in this publication may be requested from the Department of Health Victoria (infectious.diseases@health.vic.gov.au), contingent on approval of an analysis plan by this Department and relevant ethical approval. Possum faecal data may be shared, after publication, on a collaborative basis upon reasonable request made to Dr Kim Blasdell (kim.blasdell@csiro.au).