Wednesday April 9, 2025
A recent study conducted by the Barwon South West Public Health Unit and CSIRO, Australia’s national science agency, has shown evidence that Buruli ulcer in possums is present in areas up to three years prior to cases emerging in humans.
Buruli ulcer (sometimes referred to as the Bairnsdale ulcer) is a skin disease caused by the bacterium Mycobacterium ulcerans.
The toxins made by the bacteria destroy skin cells, small blood vessels and the fat under the skin, which causes ulceration and skin loss.
Cases of Buruli ulcer have increased significantly in Victoria in recent years, particularly along the Mornington and Bellarine peninsulas, and the disease is spreading into new geographical areas including Melbourne, the Surf Coast and several suburbs of Greater Geelong, in particular Belmont, Highton, Wandana Heights, Newtown, Grovedale and Marshall.
In Victoria Buruli ulcer is a zoonotic disease. Possums carry the bacteria and are known to develop disease and shed M. ulcerans in their faeces.
Since 2017, Buruli ulcer cases have increased across the region and are clustered near possums shedding M. ulcerans in their faeces.
The study examines timing and proximity of human cases to the detection of M. ulcerans DNA in possum faeces. Using systematic collection methods in surveys of possum faeces conducted in 2020 and 2022 across areas of Geelong by CSIRO, we have observed areas in Geelong with no prior human cases but where the bacteria was within the possum population prior to the emergence of clustered human cases. It showed M. ulcerans–positive faeces preceded human cases by up to 39 months, constituting an early warning of impending risk for Buruli ulcer (the ‘canary in the coalmine’).
Associate Professor Daniel O’Brien, Director of Infectious Diseases at Barwon Health, said the study confirms that possums are involved in the spread to humans and that this surveillance is a vital tool for identifying areas at risk of Buruli ulcer.,
“It is hoped that a better understanding of the ulcer and the link between finding the bacteria is possums and the time before it may appear in humans, means we can use possum surveillance to identify areas that the disease may appear in next. This will allow health officials to identify and pre-actively educate communities and health practitioners around what to look for to allow rapid diagnosis and treatment, and also how to minimise the risk of catching it. Furthermore, with its pre-warning of risk areas, it provides a tool that may allow the commencement of activities that prevent disease emerging in humans in the first place.”
“In summary, it gives us a tool to help minimise the risk of catching the disease, help ensure early diagnosis and prompt treatment of those infected and potentially help prevent its spread.”
“This is a vital step in understanding this disease that causes a lot of pain and suffering to those that have the disease. Research is vital in better understanding, and it needs more funding. We hope with increased investment we can continue to work on ways to better prevent the disease and its spread, and to trial new medicines to improve treatment for those that may suffer from this in the future,” he says.
Research has also shown that areas where humans are most frequently contracting Buruli ulcer are areas where soil, mosquitoes and possums are most frequently carrying the causative bacteria. Infections are also more likely acquired in the warmer months but can be acquired at any time of the year.
Therefore, the following precautions can reduce your risk:
- When gardening, working or spending time outdoors:
- Wear gardening gloves, long sleeved shirts and trousers
- Wear insect repellent on any exposed skin
- Protect cuts and abrasions with a dressing
- Promptly wash any new scratches or cuts you receive with soap and apply a topical antiseptic and dressing.
- Reduce mosquito breeding sites around houses and other accommodation by reducing areas where water can pool (including pot plant containers, buckets, open tins or cans, discarded tyres, and other untreated, freshwater pools).
- Mosquito proof your home by securing insect screens on accommodation.
- Avoid mosquito bites by:
- Using personal insect repellents containing diethyltoluamide (DEET) or picaridin
- Covering up by wearing long, loose-fitting, light-coloured clothing
- Avoiding mosquito-prone areas and vector biting times, especially at dusk and dawn.
- Exposed skin contaminated by soil or water should be washed following outdoor activities.
- See your doctor early if you have a slow-healing or suspicious skin lesion.
- Add line here about avoidance of handling sick possums (take it from previous press release)
Read the publication in the March issue of Emerging Infectious diseases here: