Buruli ulcer in Australia
(Mycobacterium ulcerans infection)
(March 26th 2017) Short URL: goo.gl/h3a0b4
Do you think you have a Buruli ulcer? Diagnosis by PCR is quick and accurate, but you need to ask you doctor for this non-routine test. There is information to guide your doctor below. Buruli is always curable but treatment is simpler if diagnosis is made early. “Buruli” may be a better term than Buruli ulcer, as not all cases start as ulcers and this can confuse patients and their doctors.
What is Buruli? Buruli ulcer, Bairnsdale ulcer, Mossman ulcer and Daintree ulcer are all local names given to the same disease that is caused by Mycobacterium ulcerans--a mycobacterium related to those that cause TB and leprosy. “Buruli ulcer” or just “Buruli” is the official name preferred by WHO. Mycobacterium ulcerans produces a toxin called mycolactone that damages skin and subcutaneous fat tissue. The infection occurs in humans in at least 32 countries.
Which areas in Australia and New Zealand are endemic? Buruli is a geographically restricted infection, which means it only occurs following contact with specific “endemic” areas. In Australia these include coastal Victoria, north Queensland north of Mossman, the Capricorn Coast of Queensland near Yeppoon and the tropical north coast near Darwin (see map). So far no cases have been linked to Tasmania, South Australia, southern Western Australia or the ACT. There have been a handful of cases in southern New South Wales near the border with Victoria. Buruli has not been reported in New Zealand.
How do you get infected? Travel to an endemic area for as little as one hour is enough to pick up the infection. The median incubation period is approximately 5 months with a range of 3 weeks to almost a year. In Victoria (southern temperate Australia) there is evidence that mosquitoes transmit the infection and that they in turn pick it up from possums with Buruli ulcer. However, this epidemiology may be unique to Victoria and there may be alternative reservoirs and modes of transmission elsewhere. Mycobacterium ulcerans does not appear to spread from person to person
How common? In the years 2013, 2014, 2015, 2016 combined there were at least 452 confirmed cases of Buruli in Australia, giving an approximate annual national incidence of 0.5 per 100,000. However, because Buruli occurs in small endemic regions the incidence in local populations can be any times higher than the national rate. Overseas there have been thousands of cases of Buruli, predominantly in rural areas in west and central Africa.
Map: Confirmed cases Australia since 1939 (Courtesy A/Prof John Hayman)
Map: Confirmed cases Australia, 2013-14 (WHO Meeting on Buruli ulcer, March 2015, Geneva). Circle sizes are to scale in this map
Graph: Confirmed cases in Victoria by year 1937-2016 [Acknowledgement: A/Prof John Hayman, cases prior to 1993].
Figure: Overlaid Google Earth image, likely place of infection, confirmed cases Victoria, 2013-14 (WHO Meeting on Buruli ulcer, March 2015, Geneva).
Figure: Overlaid Google Earth image, likely place of infection, confirmed cases Victoria, 2015-2016
(WHO Meeting on Buruli ulcer, March 2017, Geneva).
When to suspect Buruli ulcer? Buruli usually starts as a small spot (lesion) on or under the skin that enlarges over days to weeks. Lesions typically occur on exposed areas but especially around the ankles, backs of calves or elbows. However, they can be anywhere. Sometimes an insect bite or episode of trauma is recalled. Buruli is often painless, and fever or other symptoms are usually absent. Eventually the spot breaks down and a slowly enlarging undermined ulcer appears but appearances can be variable and Buruli is difficult to diagnose if your doctor is not familiar with it. Diagnosis is easy once Buruli is considered in the differential diagnosis as a rapid accurate test is available (PCR).
Some patients present with a raised reddish plaque rather than an ulcer or develop swelling of the whole limb or whole abdominal wall without an identifiable nodule, plaque or ulcer. Buruli progresses over days to weeks (not hours). Most severe cases of Buruli ulcer in Australia result from delayed diagnosis.
How is Buruli ulcer treated? Buruli ulcer is slow moving and always curable although it can be quite destructive. A 2-month course of antibiotics (rifampicin plus clarithromycin used together) reliably kills Mycobacterium ulcerans. Confusingly, lesions may paradoxically worsen during antibiotic treatment but this does not indicate treatment failure. Small lesions heal well with antibiotics alone, but larger ones may require conservative debridement and skin grafting to achieve the best result. Treatment guidelines for Australian clinicians are available here.
Pictures (confirmed cases from Australia)
Leg, adult female, early diagnosis.
Photo: Dr. Paul Flood, Phillip Island].
Lower back ulcer - 12 year-old boy. The markings show the area of palpable induration (swelling) that is more extensive than the ulcer itself.
[Photo: Mr. John Buntine, Melbourne]
Buruli over the Achilles tendon on a 24-year-old before and after treatment with rifampicin plus clarithromycin
Buruli over the right forearm of a 30-year-old woman with delayed diagnosis.
Notes on diagnosis for clinicians
ULCER OR DISCHARGING LESION:
Rapid accurate diagnosis can be made by PCR directly from swab of an ulcer. Make sure you get some biological material on the send of the swab by running it around the undermined edge of the ulcer.
If there is a plug of necrotic tissue, moisten this with saline. If there is biological material on the swab, the PCR is almost always positive.
Specify “Mycobacterium ulcerans” or “Bairnsdale/Buruli ulcer” and “PCR” clearly in clinical notes on the request slip.
é RAPID DIAGNOSIS FROM A SWAB...PCR can be performed straight from the swab; make sure you can see biological material on the swab (see picture). Moisten and rub with saline if necessary.
PLAQUE, SWELLING or CELLULITIS BUT NO ULCER, fresh tissue from an incisional biopsy, punch biopsy, fine needle aspirate or excisional biopsy will be needed. Remember to ask for Mycobacterium ulcerans PCR microscopy and culture. Histology is also very helpful.
Ankle - 23 year-old woman, plaque lesion (no ulcer apparent; diagnosed by histology and PCR on a incisional biopsy)
Microscopy: Acid-fast bacilli (Mycobacterium ulcerans) in a smear taken directly from a swab of an ulcer. The bacteria can be clearly seen as red clumps on a blue background. PCR confirmed this is M. ulcerans
Links to guidelines, articles and useful sites
Department of Health (Victorian State Government)
Publications about Buruli ulcer in Victoria, Australia
Buruli ulcer in Far North Queensland
Buruli ulcer in coastal central Queensland
World Health Organization
Public Library of Science (Journal)
Medical Journal of Australia
Proceedings of the National Academy of Science (Journal)
Genome Research (Journal)
About this website
short URL: http://goo.gl/h3a0b4
This is a privately funded website provided as a community service. The information is intended as a guide only and should not replace medical advice from your doctor. Latest update March 2017. If you have questions/concerns about the contents or accuracy of this website please contact me by email: Paul.JohnsonATaustin.org.au
Paul Johnson (Austin Health Link)
Professor Paul Johnson
Austin Health & University of Melbourne
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