Melbourne GPs told to consider Buruli ulcers when assessing lesions

Evelyn Lewin

25/02/2021 3:45:35 PM

The flesh-eating infections are the result of bacteria that is thought to be transmitted by mosquitoes.

Mosquitoes are thought to be the key vectors of Mycobacterium ulcerans.

Buruli ulcers have been found in the inner-Melbourne areas of Essendon, Moonee Ponds and Brunswick West – making these the first non-coastal areas in Victoria to be recognised as a potential area of risk.
On 23 February, Victorian Chief Health Officer Professor Brett Sutton issued a health advisory stating ‘several’ cases of Buruli ulcer have occurred in these regions.
He says the recent detection of Mycobacterium ulcerans (M. ulcerans) – the bacterium responsible for Buruli ulcers – in Melbourne’s inner-north means this location is ‘a new area of interest’.
Tim Stinear, Professor of microbiology at the Peter Doherty Institute for Infection and Immunity at the University of Melbourne, told newsGP he is worried about this new development.
‘We are concerned,’ he said.
‘We’re concerned enough to try and stop the disease spreading.’
However, Professor Sutton notes the risk of acquiring a Buruli ulcer in these areas is low, and Professor Stinear echoes that message.
‘It is low level, that’s the point, [it is just] a handful of cases over the past five years,’ Professor Stinear said.
Buruli ulcer expert Professor Paul Johnson says the message is for people to be aware, but not alarmed.
‘The purpose of the health alert is to draw the attention of local doctors and the public to it, not to cause panic because it’s actually quite a slow moving disease,’ he said.
‘It’s not a massive increase in cases, it’s just a definite change in the epidemiology that we need to monitor closely.’
Professor Stinear wants clinicians to keep Buruli ulcers in mind as a differential diagnosis when assessing skin lesions.
Overall, there were 218 cases of Buruli ulcer recorded in Victoria in 2020, and already 21 have been confirmed in 2021 – which is an increase compared to the same period last year.
The lesion itself usually presents as a slowly growing painless nodule or papule like an insect bite. Over one to two months, it can ulcerate.
‘It’s a tricky disease to diagnose in one sense because it’s rare, so you need to think of the diagnosis in order to ask for the test,’ Professor Stinear said.
Once the diagnosis is suspected, Professor Stinear says testing is straightforward.
The gold standard test for M. ulcerans is polymerase chain reaction (PCR) performed on swabs taken from the undermined edge of the ulcer. These tests are subsidised and should attract no out-of-pocket cost for patients, apart from a possible handling fee in private pathology.
‘It’s a really good diagnostic test,’ Professor Stinear said.
‘If you think of the diagnosis and get the test and it is positive, there are antibiotics that will heal this infection; a combination of rifampicin and clarithromycin as recommended by the World Health Organization.
‘And early diagnosis is key for the best outcomes.’
Professor Stinear notes there have been ‘ad hoc’ cases of Buruli ulcer reported through Melbourne over the past 20 years.
However, in those cases it was not always clear where a patient acquired the infection.
‘Over the past five years there’s been one or two cases from the Essendon, Brunswick West areas, and those cases haven’t had clear links to known Buruli areas,’ he said.
‘But you could never be sure if it was a new cluster in Essendon, or if it was just people that picked up the disease during their holiday.’
He says the difference now is that there is strong evidence to show these infections stemmed from the suburbs listed in the alert.
The gathering of this evidence started last year, when ‘an observant resident’ in Essendon noticed a possum with a lesion on its foot.
After being examined and tested, the possum was diagnosed with a Buruli ulcer.
Investigators then performed possum fecal surveys in the area, which showed that other possums were also shedding the bacterium. Genomic testing matched the bacterium from the possums with those isolated from clinical cases in the area.
‘So it’s these multiple lines of evidence that gives us the confidence to say that there is low-level spread of Buruli ulcer in the northern suburbs,’ Professor Stinear said.
Buruli ulcers are not transmitted from person-to-person, and there is no evidence of spread from possums directly to humans.
Instead, mosquitoes are thought to be the key vectors, and Professor Stinear is hoping to reduce transmission by controlling their numbers in areas where the disease is known to be active.
He is doing this through his role as chief investigator of the Beating Buruli study, which commenced in 2018 and received further funding last year to ensure it continues for another three years.  
The goal of the study is to reduce mosquito numbers to a level where they’re not going to spread disease and provide evidence-based public health interventions for the prevention of developing Buruli ulcer.
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