Buruli ulcer (also known as Bairnsdale ulcer) is an infection of skin and soft tissue caused by the bacterium Mycobacterium ulcerans. The toxin made by the bacteria attacks fat cells under the skin, which leads to localised redness and swelling or the formation of a nodule (lump) and then an ulcer.
Although Buruli ulcer is not fatal, the infection can often leave people with significant cosmetic, and sometimes functional, damage to limbs.
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. Over the past few years, Victorian scientists have been conducting intensive research in a search for answers around the puzzling aspects of this condition. Although it's understood that the infection is picked up from the environment, it's not yet known exactly how humans become infected with the bacteria, or where in the environment the bacteria prefer to live. It is not thought to be spread person-to-person.
The Beating Buruli in Victoria research project
The ‘Beating Buruli in Victoria’ project received its first National Health and Medical Research grant in 2018, allowing the collaborative partnership established between the Doherty Institute, Victorian Department of Health, University of Melbourne, Barwon Health, Austin Health, CSIRO, Agriculture Victoria, and the Mornington Peninsula Shire Council, to undertake ambitious and innovative research to better understand how Buruli ulcer is transmitted in Victoria, and to determine effective ways to reduce and prevent human infections.
Findings from an earlier case-control study conducted in 2004 on the Bellarine Peninsula showed that getting bitten by mosquitoes, as well as gardening, were possible risk factors for getting Buruli ulcer, while wearing insect repellent protected against infection. Further research, including laboratory studies and mapping the distribution of Buruli ulcer lesions in case, strengthened the evidence that mosquitoes might play a significant role in transmission. Earlier research has also shown that Australian native possums can be victims of Buruli ulcer too.
The next phase
A new three-year research project is planned to commence in February 2021 which hopes to actively disrupt disease transmission for the first time and lead to the development of evidence-based policies and guidelines that can help stop the spread of Buruli ulcer around Victoria and even globally.
The study will focus on the 'hotspot' areas of the Mornington Peninsula that were identified as having the highest risk of Buruli ulcer transmission.
The trial addresses community concerns raised in 2019 around spraying to control adult mosquitoes. The new intervention study and associated control measures are based on well-established mosquito source reduction strategies that don’t involve spraying. Source reduction strategies include:
- Education campaigns to help homeowners reduce potential breeding habitats for container breeding mosquitoes on their properties, for example in roof gutters and around pot plants.
- Use of simple, cost-effective and non-toxic mosquito traps (called Gravitraps) that reduce mosquito numbers in and around homes.
- Use of commercial, non-toxic mosquito-specific larvicides such as NoMoz in backyard mosquito breeding sites including rain-water tanks, septic tanks, ponds and bird baths.
The first step of the source reduction intervention is to conduct a pilot study, beginning in February 2021, to show that the strategy will effectively reduce mosquito numbers on the Mornington Peninsula. The pilot study will involve recruiting approximately 500 households divided into 10 zones across Blairgowrie and Rye. Five of these zones (250 houses) will be classified as intervention zones, where the mosquito source reduction activities outlined above will take place during a four-week period. The remaining five zones (250 houses) will be control zones, where no activities will occur. Comparing mosquito numbers in the two zones will allow us to measure the effectiveness of the intervention.
Phase 2 of the project is scheduled to take place during summer of 2021/2022, with larger-scale mosquito activities to occur throughout the Mornington and Bellarine peninsulas. The interventions will focus on mosquito source reduction methods, aiming to reduce mosquito breeding sites in stagnant water on private and public land. It will involve a door-to-door program, where members of the study team will help home and business owners in the intervention areas to identify mosquito breeding sites on their property, and then implement steps to reduce mosquito numbers. These methods have been used successfully around the world to reduce mosquito populations, in a sustainable and ecologically friendly way.
The study team is planning to work in partnership with the district councils in all study areas, to ensure that communities within the study areas are fully informed and supportive of the project.