What is the issue?
Buruli ulcer is a skin infection caused by the bacterium Mycobacterium ulcerans (M. ulcerans) usually presenting as a slowly developing painless nodule or papule which can initially be mistaken for an insect bite. Over time the lesion can progress to develop into a destructive skin ulcer which is known as Buruli ulcer or Bairnsdale ulcer.
The highest risk is associated with the active transmission areas of Rye, Sorrento, Blairgowrie and Tootgarook on the Mornington Peninsula. There is a moderate risk associated with areas in the Bellarine Peninsula (Ocean Grove, Barwon Heads, Point Lonsdale, Queenscliff), Frankston and Seaford areas. There is a low risk associated with the rest of the Bellarine and Mornington Peninsula, the South Eastern Bayside suburbs and East Gippsland. Together, all these areas are considered the endemic parts of Victoria for Buruli ulcer transmission.
Recent cases from Aireys Inlet on the Surf Coast and the Geelong suburb of Belmont suggest that these are emerging areas of local transmission. Two cases were identified in residents in Aireys Inlet and two in Belmont during 2019, with no known travel to an endemic area. The risk of transmission in these areas is considered low.
In 2018 there were 340 cases of Buruli ulcer reported in Victoria. This compares with 277 cases in 2017, 182 cases in 2016 and 107 cases in 2015. There have been 240 cases of Buruli ulcer notified in 2019 year to date in Victoria.
When recognised early, diagnostic testing is straightforward if guidelines are followed (see below) and prompt treatment can significantly reduce skin loss and tissue damage, as well as lead to more simplified treatment.
Who is at risk?
Everyone is susceptible to infection. While it can occur at any age, people aged 60 years and over have a higher rate of notification of Buruli ulcer in Victoria. Individuals who live in or visit endemic areas are considered at greatest risk.
Symptoms and transmission
The incubation period has been estimated to vary from four weeks to nine months, with a median of four to five months. There is a peak in diagnoses in Victoria between June and November each year; however cases are diagnosed year round.
The first sign of Buruli ulcer is usually a painless, non-tender nodule or papule. It is often mistaken for an insect or spider bite and is sometimes itchy. The lesion may occur anywhere on the body, but it is most common on exposed areas of the limbs. In one or two months the lesion may ulcerate, forming a characteristic ulcer with undermined edges. Presentation can also include painful nodules, and cases involving oedema and cellulitis can present with severe pain and fever. Patients with atypical presentations may require alternative diagnostic tests (see below).
The bacterium produces a unique toxin known as mycolactone that inhibits the immune response whilst continuing to damage tissue. If left untreated, extensive ulceration can occur, requiring surgical management.
Occasionally the disease may present as a firm, painless elevated plaque or a large area including a whole limb may be indurated by oedema without an ulcer. Oedematous lesions are a less common but represent a more severe form of disease and are more likely to be accompanied by fever and pain. In patients with cellulitis that does not respond as expected to usual antibiotics, the diagnosis of Buruli ulcer should be considered, especially in those with reported exposure to an endemic area and cellulitis that has affected the ankle, wrist or elbow regions.
Transmission pathways of M. ulcerans are not well understood. The bacteria may enter through broken skin, and both mosquitoes and some water-dwelling insects have been implicated in the transmission pathway. Most cases report some form of skin trauma, including insect bites, prior to the development of the lesion. The disease is not transmissible from person to person.
‘Beating Buruli in Victoria’ is a two-year research project currently underway through a collaborative partnership between DHHS, the Doherty Institute, Barwon Health, Austin Health, CSIRO, Agriculture Victoria, the University of Melbourne and Mornington Peninsula Shire. The project aims to better understand how Buruli ulcer is transmitted and determine effective ways to prevent infections and reduce its spread into new areas.
Evidence to date suggests that mosquitoes play a role in the transmission of M. ulcerans. Exposures to contaminated soil or water following outdoor activities have also been identified as possible sources for transmission. Therefore, the best way to prevent infection is through the use of simple precautionary measures.
- Use preventative measures to avoid insect bites, such as fly screens, using insect repellent, wearing long sleeves and trousers when outside, and reducing mosquitoes and their habitat around houses in endemic areas. More detailed advice on how to prevent being bitten by mosquitoes can be found at Better Health Channel - Beat the Bite
- Wear appropriate protective clothing when gardening or undertaking recreational activities in endemic areas
- Cuts and abrasions should be cleaned promptly following outdoor activities (eg gardening, recreational activities) in endemic areas, and exposed skin contaminated by suspect soil or water should be washed.
Early diagnosis and treatment can prevent serious complications from the ulcer. It is important to remember:
- The presence of skin lesions (red patch, ulcer, lump, or pimple) that progress rather than heal, even after a brief visit to an endemic area, should be assessed by a doctor and tested for Buruli ulcer.
- The time from exposure to the first symptom (the incubation period) can be up to 10 months (the average is around 5 months).
If an ulcer is present or if a scabbed lesion can be deroofed, two dry swabs (or pre-moistened with sterile saline) from beneath the undermined edges of the lesion should be sent for staining for acid-fast bacilli (AFBs), polymerase chain reaction (PCR) and culture. It is essential that there is visible clinical material on the swab. Please state on the request form that Buruli ulcer or M. ulcerans is suspected so that one swab can be reserved for PCR testing by the Victorian Infectious Diseases Reference Laboratory (VIDRL) and not split for other laboratory testing such as culture.
If an eschar cannot be deroofed or in the event of atypical presentation with plaque, oedema and/or cellulitis, a swab will return a false negative and will not be useful. In these cases, fine needle aspirate (FNA), a punch biopsy, or excisional skin biopsy will be required for diagnosis. The biopsy should be sent for histology, and fresh tissue should be sent for AFB staining, specific PCR and mycobacterial culture. The suspected diagnosis should be noted on the request slip.
PCR testing at VIDRL for Buruli ulcer is now free for patients (although a handling fee may still apply for private pathology collection services). General practitioners should include Medicare details so that the test can be bulk billed. Public hospitals can also test for Buruli ulcer free of charge.
A positive smear for AFBs makes the diagnosis likely. Culture or PCR is required for confirmation. A negative smear does not exclude the diagnosis. The PCR test is only performed by the Victorian Infectious Diseases Laboratory (VIDRL) or via Melbourne Pathology and can confirm the diagnosis in a few days. The Melbourne Pathology testing may take longer as it is sent interstate. Culture usually takes eight to 12 weeks.
Under the Public Health and Wellbeing Regulations 2009, Buruli ulcer must be notified in writing by medical practitioners and persons in charge of laboratories within five days of diagnosis.
Referral for treatment to doctors experienced in the management of this condition is recommended. The current mainstay of treatment is rifampicin-containing combination oral antibiotic therapy. Surgery may be used in combination with antibiotic therapy, where indicated.
Blue Book - Mycobacterial infections (non-tuberculosis)
Notifying Buruli ulcer cases
RACGP training module on Buruli ulcer
Buruli ulcer in Australia
Better Health Channel - Buruli ulcer
For further information please contact the Communicable Disease Prevention and Control section at the Department of Health on 1300 651 160.
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