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.
Cases from Aireys Inlet on the Surf Coast and the Geelong suburb of Belmont in 2019 suggested that these are emerging areas of local transmission.
The recent detection of M. ulcerans in Melbourne’s inner north means this location is a new area of interest. This is the first non-coastal area in Victoria to be recognised as a potential area of risk, however, the risk of transmission in these areas is considered low. All the identified cases had also travelled to known risk areas for Buruli Ulcer but genetic analysis of M. ulcerans isolated from them strongly supports a common link. The potential source of M. ulcerans in Melbourne’s inner north has not been established, although the bacteria were isolated from the faeces of a local possum.
The disease is not transmissible from person to person and there is no evidence of transmission from possums directly to humans.
Who is at risk?
Everyone is susceptible to infection. Disease can occur at any age, but Buruli ulcer notifications are highest in people aged 60 years and above in Victoria. Individuals who live in or visit endemic areas are considered at greatest risk.
Essendon, Moonee Ponds and Brunswick West areas of inner-Melbourne are new areas of interest, in which the risk of contracting Buruli Ulcer is considered low.
When recognised early, diagnostic testing is straightforward. If guidelines are followed prompt treatment can significantly reduce skin loss and tissue damage, as well as lead to more simplified treatment.
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. In Victoria, case reporting peaks in between June and November each year; however, cases are reported 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. People of any age can be infected. 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 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.
A ‘Beating Buruli in Victoria’ research project is currently underway. A collaborative partnership between the Department of Health, the Doherty Institute, Barwon Health, Austin Health, Agriculture Victoria, the University of Melbourne and Mornington Peninsula Shire aims to better understand how Buruli ulcer is transmitted and determine effective ways to reduce infections and its spread into new areas.
Evidence to date suggests that mosquitoes play a role in the transmission of M. ulcerans. The species of mosquito which has been implicated in other areas of Victoria is Aedes notoscriptus (Ae. notoscriptus), which is a known to breed in open containers with pooled water. Discarded car and truck tyres, open tins or cans, buckets and untreated pools and other still or standing water are breeding grounds for this species of mosquito.
Preventive measures include:
- Avoid insect bites by using fly screens, insect repellent, wearing long sleeves and trousers when outside.
- Wear gardening gloves, long sleeved shirts and trousers when gardening or working outdoors
- Reduce mosquito breeding sites around houses and other accommodation by reducing areas where water can pool (including pot plant containers, buckets, tin cans, discarded tyres, and other untreated, freshwater pools).
- Cuts and abrasions should always be cleaned promptly following outdoor activities (e.g. gardening, recreational activities). Exposed areas of skin which have been exposed to soil or water from a known endemic area should be washed with soap and running water.
- Follow the tips on Beat the Bite
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 area of increased risk of transmission of Buruli Ulcer 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).
- More detailed advice on how to prevent mosquito bites can be found at Beat the Bite
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 (AFB), polymerase chain reaction (PCR) and culture. It is essential that there is visible clinical material on the swab.
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.
Please specify on the specimen request form that Buruli ulcer or M. ulcerans is suspected so that one swab is reserved for PCR testing by our public health reference laboratory, the Victorian Infectious Diseases Reference Laboratory (VIDRL) and not split for other laboratory testing such as culture.
PCR testing at VIDRL for Buruli ulcer is free for patients (a handling fee may still apply for private pathology collection services). General practitioners should include their patient’s 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 AFB 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
Better Health Channel - Buruli ulcer
For more information please contact the Communicable Disease Prevention and Control section at the Department of Health on 1300 651 160 (24 hours). .
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