Buruli ulcer

What is Buruli ulcer caused by?

Buruli ulcer (Buruli) is an infection of skin and underling soft tissue caused by Mycobacterium ulcerans (MU). Infection is from the environment to you, not from person to person. You only get infected in very specific places (“endemic areas”), as MU is not everywhere. In the world there are at least 33 countries with endemic areas. In Australia active endemic areas include coastal towns in Victoria and now inner suburbs of Melbourne and Geelong, far North Queensland between Mossman and the Daintree River and most recently Bateman’s Bay in New South Wales. Most Australian Buruli is acquired in Victoria.

What does a Buruli ulcer look like?

Typically, Buruli lesions are single, slowly progressive and occur on exposed parts of the body where mosquitoes bite you, but many months later (median of about 5 months). An ulcer may not be there initially. A hallmark of Buruli is it just keeps progressing and does not respond to standard antibiotics. People usually seek medical help after a few weeks because of persistence and increase in size, and sometimes older people think they may have a skin cancer. There are other presentations too – relatively rapid swelling and redness of a whole limb or part of a limb (cellulitis) or a raised red lesion without an ulcer (plaque). Anyone can get Buruli ulcer including children.

How do you get infected with Mycobacterium ulcerans?

In Victoria Buruli is transmitted by mosquitoes. A major breakthrough in understanding Buruli in Victoria came when we discovered that possums, particularly ringtail possums, also suffer from Buruli ulcer. Wherever there are human cases we find possums with Buruli living in the trees above, and possum excreta on the ground below that tests positive for Mycobacterium ulcerans by PCR. Mosquitoes pick up Mycobacterium ulcerans from possums by direct contact (eg. by biting possums with Buruli lesions) or indirect contact (eg. from contaminated possum excreta in house gutters and street drains). Transmission in Victoria occurs in the mosquito season (summer and autumn) but people with confirmed Buruli are most often diagnosed in winter and spring. This paradox is explained by the long incubation period, typically around 5 months.

How do you prevent Buruli ulcer?

Buruli is transmitted by mosquitoes . If you live in or visit a Buruli endemic area, protect yourself against bites and reduce mosquito breeding sites on your property.

How do you diagnose Buruli ulcer?

Diagnosis is straightforward once you or your doctor think of Buruli. If there is an ulcer, a doctor can obtain a swab. Make sure that biological material is visible on the swab before sending. You may need to rub the central plug of dead tissue with the swab or soak it in saline and go back to the plug to loosen it up, to ensure a good sample. It is essential to write “Buruli ulcer PCR and culture” clearly on the pathology request form. The PCR test is very accurate if the swab is collected correctly.

How do you diagnose Buruli if there is no ulcer yet?

If there is a suspicious progressive cellulitis or plaque, then a punch biopsy is needed. Do not swab in tact skin, the infection is below the skin and the test will be falsely negative. Once again it is important that the biopsy specimen is sent for “Buruli ulcer PCR and culture”

Buruli plaque lesion – progressive increase in size over 4 weeks:

What is the best treatment for Buruli ulcer?

Standard treatment is 8 weeks of two special oral antibiotics given together – usually rifampicin and clarithromycin. This will reliably kill Mycobacterium ulcerans but it takes much longer to fully heal. People typically need regular dressings for many weeks after completing their curative antibiotics.

Can Buruli ulcer heal by itself?

Occasional patients may be able to spontaneously heal their own ulcers without surgery or antibiotics. At present we recommend antibiotics for everyone.

Does Buruli get worse before it gets better?

YES, sometimes anyway. Buruli “Paradoxical reactions” or “IRIS” (immune reconstitution inflammatory syndrome) is most likely in those with large ulcers or plaques. This happens because active antibiotics stop the production of toxin allowing your own immune system to get to work. You may notice increased swelling, redness, pain, a larger ulcer or even new ulcers. There may also be profuse drainage of liquefied fat which will be full of dead bacteria. This is part of the natural healing process and is not usually a sign of a new or out of control infection. You may need specialist advice to guide your through this phase of your recovery.

Links to public information on human Buruli ulcer

Buruli outbreak in the inner northern suburbs of Melbourne – Western Public health Unit (WPHU) [Brunswick West, Coburg, Essendon, Moonee Ponds, Pascoe Vale South, Strathmore]

South East Public Health Unit (SEPHU) – information on Buruli ulcer

Barwon Southwest Public Health Unit – Buruli in Geelong

Victorian Department of Health – Buruli alert (October 2023)

Buruli ulcer at Bateman’s Bay

Links to selected new publications

e-life Journal: Possums and Buruli ulcer in Victoria, Australia (2023)

Skin swab study of healthy volunteers in endemic regions of Victoria (2023)

Season of transmission in Victoria (2024)

Mosquitoes provide a transmission route between possums and humans for Buruli ulcer (Nature Microbiology 2024)

Transmission of Buruli ulcer and the Philosophy of Science (Nature Research Communities Blog)

Links to key past Scientific Papers – pathogenesis, epidemiology, reservoir and transmission

Development of the Mycobacterium ulcerans diagnostic PCR (1997)

First detection of Mycobacterium ulcerans in the environment (1997)

Insects in the transmission of Mycobacterium ulcerans (1999)

Mycolactone – the toxin produced by Mycobacterium ulcerans (1999)

A plasmid encodes production of mycolactone by Mycobacterium ulcerans (2004)

First evidence that mosquitoes transmit Mycobacterium ulcerans (mosquito trapping results Point Lonsdale, Victoria, Australia) (2007)

First evidence that mosquitoes transmit Mycobacterium ulcerans (case control study, Bellarine peninsula, Victoria, Australia) (2007)

The whole genome of Mycobacterium ulcerans – evidence of niche adaptation and loss of ability to live freely in the environment (2007)

The full picture emerges: Buruli is a Zoonosis – Possums, mosquitoes and Buruli ulcer in Victoria, Australia (2010)

Close correlation between mosquitos carrying Mycobacterium ulcerans and risk of human Buruli (Bellarine peninsula) (2011)

Incubation period of Buruli ulcer in Victoria – 1 (2013)

Mycobacterium ulcerans Fails to Infect through Skin Abrasions in a Guinea Pig Infection Model: Implications for Transmission (2014)

Location of 649 Buruli lesions on the human body, Victoria, Australia (2017)

Incubation period of Buruli ulcer in Victoria -2 (2018)

Skin temperature variation does not explain Buruli lesion distribution (2020)

Podcasts on Buruli ulcer in Australia:

Breaking Buruli Part 1 – ABC Science Friction (Paul Johnson and Tim Stinear)

Breaking Buruli Part 2- ABC Science Friction

Spot Diagnosis – Skin Institute

Buruli in Victoria -(graph) confirmed cases by year.

Editorials in The Lancet

Buruli ulcer: Here today but where tomorrow?

Buruli ulcer: Cured by 8 weeks of antibiotics?

Surgery for Buruli ulcer in the antibiotic era

Buruli ulcer in animals for vets

Victoria is almost unique in the world for naturally occurring cases of Buruli ulcer in a range of species other than humans. It is not clear whether M. ulcerans has a very special ecology here or this anomaly is just due to heightened awareness because of the ongoing human epidemic. For unknown reasons the two most susceptible vertebrates appear to be ringtail possums and humans!

Clinically significant Buruli ulcer has also been identified in cats, dogs, horses, alpacas and possums (so far).

Sick possums or occasionally other species are often brought to vets in Buruli endemic areas. Currently these include the whole of the Mornington and Bellarine Peninsulas, the inner northern suburbs of Melbourne and some suburbs in Geelong. A confirmed case in a possum in a non-endemic area is an important indicator and should be reported to your local public health unit.

Pictures: Ringtail possum nose and tail lesions (see full articles below from 2010 and 2014).

Attributions for photos: O’Brien CR et al 2014 https://doi.org/10.1371/journal.pntd.0002666; Fyfe JA et al.2010 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2919402/

Links to published articles on Buruli ulcer in Animals:

Buruli ulcer and Australian wildlife (Wildlife health Australia)

Mycobacterium ulcerans in two horses in south-eastern Australia (2010)

A Major Role for Mammals in the Ecology of Mycobacterium ulcerans (2010)

Localised Mycobacterium ulcerans infection in four dogs (2011)

Mycobacterium ulcerans infection in two alpacas (2013)

Buruli ulcer in humans and animals (2013)

Clinical, Microbiological and Pathological Findings of Mycobacterium ulcerans Infection in three Australian Possum species (2014)

Buruli ulcer in the News (Australia)

ABC New South Wales

Beating Buruli Team shortlisted for the 2024 Eureka Science Prize!

About this website

Professor Paul Johnson is an Infectious Diseases Physician who for 30 years has led and co-led Buruli research teams in Victoria. Together we developed the Buruli diagnostic PCR now used worldwide, were the first to identify Mycobacterium ulcerans in the environment anywhere, identified possums as the local environmental reservoir and mosquitoes as the mode of transmission in Victoria. Paul also has extensive clinical experience with Buruli ulcer and developed the first Australian Buruli Consensus treatment guidelines in 2007 which have since been updated with my colleague A/Prof Dan O’Brien in 2014. Paul has been a member of the WHO Technical Advisory Group on Buruli ulcer since 1998.

Link to University of Melbourne

Link to Google Scholar

Link to Austin Health

Comments welcome, please contact me ([email protected])

This website is provided as a public service. It replaces a long standing predecessor hosted by ozemail (which no longer exists!)

(http://members.ozemail.com.au/~groverjohnson/Mulcerans.htm)