Buruli ulcer (Mycobacterium ulcerans)

Buruli ulcer is an infection of skin and soft tissue 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. Some people have a raised, red lesion called a plaque. The ulcer can cause serious and extensive if diagnosis is delayed. Since the ulcer gets bigger with time, early detection, diagnosis and prompt treatment can minimise skin loss and other health harms from Buruli ulcer.

There is strong evidence that Mycobacterium ulcerans is present in some possums, and is transmitted by mosquitoes who first bite the possum, and then bite a person.

Who is at risk?

Cases of Buruli ulcer have increased in Victoria in recent years. The disease is spreading into new geographical areas and there are now twelve suburbs in the Western Public Health Unit catchment where there is a risk of Buruli ulcer. These are:

• Aberfeldie
• Ascot Vale
• Brunswick
• Brunswick East
• Brunswick West
• Coburg
• Essendon
• Maribyrnong
• Moonee Ponds
• Pascoe Vale
• Pascoe Vale South
• Strathmore

How does Buruli ulcer spread?

Buruli ulcer is transmitted from possums to people via mosquitoes. Reducing mosquitoes on your own property will reduce your risk of infection.

Buruli ulcer can take many months to develop after a mosquito bite. People are often exposed during the main mosquito season, from early November to late April. It then takes between 4-5 months to develop Buruli ulcer after a bite by an infected mosquito. This means that often people develop the ulcer in winter or spring after the mosquito season is over. Recognising Buruli ulcer can be difficult but the infection should be considered when a skin lesion relentlessly progresses over time despite standard treatment.

The importance of an early diagnosis

Once diagnosed, Buruli ulcer can be cured with a specific type of antibiotics. It is important to get a diagnosis from a doctor as early as possible. If diagnosis is delayed the ulcer can become very large. The ulcer can lead to deformity, disability, or bone infection.

How to recognise Buruli ulcer

• Buruli ulcer may start like a bite or as a lump under the skin that gets bigger over days or weeks.
• Buruli ulcer occurs on areas of the body where mosquitoes bite, including the ankle, lower leg and arms. 
• Unlike other ulcers, Buruli ulcer often does not hurt. Usually, people do not have fever or other symptoms of infection.

What to do if you have a new or persistent sore, ulcer or skin infection

See your GP. Ask about getting an easy Buruli ulcer test.

Preventing Buruli ulcer

Reduce the number of mosquitoes around your property by:

• removing or covering areas where mosquitos breed with mosquito wire, such as gutters, pot plant containers, buckets, open tins or cans. Empty out stagnant water
• making sure your water tank is screened off to prevent mosquitoes from breeding there
• mosquito-proofing your home by installing insect screens.

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 especially at dusk and dawn when they are most likely to be out.

Reducing your risk of mosquito bites, especially during mosquito season (early November to late April) and especially around your own property, can greatly reduce your risk of Buruli ulcer.

For more information on protecting yourself from mosquito bites, click here.

Professor Paul Johnson is an Infectious Diseases Physician who for 30 years has led or co-led Buruli ulcer research in Victoria and has extensive clinical experience with Buruli ulcer.

For more information about Professor Paul Johnson and Buruli ulcer, visit his website here.

Buruli ulcer information for health professionals

Cases of Buruli ulcer have increased in Victoria in recent years. The disease is spreading into new geographical areas and there are now twelve suburbs in the Western Public Health Unit catchment where there is a risk of Buruli ulcer. These are:

• Aberfeldie
• Ascot Vale
• Brunswick
• Brunswick East
• Brunswick West
• Coburg
• Essendon
• Maribyrnong
• Moonee Ponds
• Pascoe Vale
• Pascoe Vale South
• Strathmore

Buruli ulcer is an infection of skin and soft tissue caused by the bacterium Mycobacterium ulcerans. The toxins made by the bacteria destroy skin cells, small blood vessels and the fat under the skin. Ulcers appear as the infection spreads in the fat layer beneath the skin. The damage caused can be serious and extensive if diagnosis is delayed.

Local research has confirmed that Buruli ulcer is transmitted from possums to people via mosquitoes. The type of mosquitoes that are pests in backyards – especially the common container-breeding mosquito Aedes notoscriptus – are the main risk. Reducing mosquitoes on your own property will reduce your risk of infection.

The median incubation period is 4-5 months with a range of 1-10 months. Often ulcers appear 4-5 months after mosquito season (which runs from early November to late April) and so cases present to care or are diagnosed in winter or spring.

Generally, 80-90 per cent of cases have an ulcer, while some others have relatively slowly progressing cellulitis that does not respond to standard treatment. The majority of ulcers develop on areas of the body where mosquitoes bite, including the ankle, lower leg and arms.

Consider Buruli ulcer in patients with an ulcer who live or have exposure in an area of risk. 

Testing

Test ulcers for M. ulcerans by taking a swab from the undermined inside of the edge of an ulcer, ensuring you can see biological material on the swab. It is important to specifically request M. ulcerans smear, culture and PCR as laboratories will not routinely do these tests.

If there is a plaque with no ulcer, a punch biopsy that samples the subcutaneous layer will be required.

Treatment

Treatment is generally with rifampicin and clarithromycin for 8 weeks. Information and guidelines on treatment of Buruli ulcer are available on Health Pathways and through the Therapeutic Guidelines (Antibiotic). WPHU recommends discussion with an infectious diseases specialist to confirm dose and follow-up required.

If there are any challenges with accessing ID specialist advice, WPHU can assist linking general practitioners to specialist Buruli ulcer care at the Royal Melbourne Hospital for patients who reside in the WPHU catchment – contact WPHU on 1800 497 111 to discuss. Please note that dressings may be required for weeks after antibiotics are completed. Surgery is reserved for specific situations and is not usually required.

Notification

Mycobacterium ulcerans infection is a notifiable disease in Victoria under the Public Health and Wellbeing Act 2008. Clinicians must notify all confirmed cases, which can be done by completing the online notification form.

Resources

See this useful summary for further information about identification, testing and treatment of Buruli ulcer.

Professor Paul Johnson is an Infectious Diseases Physician who for 30 years has led or co-led Buruli research teams in Victoria. Paul has extensive clinical experience with Buruli ulcer and developed the first Australian Buruli Consensus treatment guidelines in 2007 which have since been updated. Paul has also been a member of the WHO Technical Advisory Group on Buruli ulcer since 1998.

For more information about Professor Paul Johnson and Buruli ulcer, visit his website here.

Last updated: 12 December 2025