Buruli ulcer

About Buruli ulcer

Buruli (also known as Bairnsdale) ulcer is a skin disease caused by the bacterium Mycobacterium ulcerans. The toxins made by the bacteria destroy skin cells, small blood vessels and the fat under the skin, which leads to ulceration and skin loss.

These bacteria are found in the environment – for example, they have been detected in mosquitoes, vegetation and possum poo from some possum species in areas where there are cases of Buruli ulcer.

It is not known exactly how humans become infected. In Victoria, there is increasing evidence that mosquitoes and possums have a role in transmitting the infection.

The disease is spreading geographically across Victoria and is no longer restricted to specific locations.

The number of cases in Victoria varies widely from year to year, but numbers have been increasing to between 200 to 340 cases per year since 2017.

Buruli ulcer is not known to be transmitted from person-to-person, however, household members of people with Buruli ulcer should self-monitor for any non-healing skin lesions and seek early medical assessment as they may have been exposed to the same environmental source.

Symptoms of Buruli ulcer

The progression of symptoms can include:

• A spot that looks like a mosquito or spider bite forms on the skin (most commonly on the limbs).
• The spot grows bigger over days or weeks.
• The spot may form a crusty, non-healing scab.
• The scab then disintegrates into an ulcer.
• The ulcer continues to enlarge.
• Unlike other ulcers, this ulcer is usually painless and there is generally no fever or other signs of infection.
• The infection may sometimes present with no ulceration but with localised pain, swelling and fever, raised lumps, or thickened or raised flat areas of skin.

Locations of Buruli ulcer outbreaks

Buruli ulcer has been reported in 33 countries around the world. Affected areas include rural West Africa, Central Africa, New Guinea, Latin America and tropical regions of Asia.

In Australia, Buruli ulcer is known to occur in several states, including Queensland, the Northern Territory and Victoria.

In Victoria, up until recently the disease was most commonly reported in localised, coastal areas across the state. There have been three recognised levels of risk in Victoria where Buruli ulcer is endemic (constantly present in the community):

• The highest risk is associated with the active transmission areas of Rye, Sorrento, Blairgowrie and Tootgarook on the Mornington Peninsula.
• Moderate risk areas are Frankston and Seaford on the eastern side of Port Phillip Bay, and the Bellarine Peninsula (Ocean Grove, Barwon Heads, Point Lonsdale, Queenscliff) on the western side of Port Phillip Bay.
• Low risk areas included the remaining areas of the Bellarine and Mornington Peninsula, the South Eastern Bayside suburbs and East Gippsland.

More recently, the disease has been observed to be spreading geographically across Victoria and is no longer restricted to coastal areas or specific locations. Since 2019, cases have been reported in the below locations suggesting these as emerging areas of local transmission:

• Aireys Inlet and the Surf Coast
• Several suburbs of Greater Geelong, in particular Belmont, Highton, Newtown, Wandana Heights, Grovedale and Marshall
• Inner Melbourne suburbs of Essendon, Moonee Ponds, Brunswick West, Pascoe Vale South and Strathmore

However, the overall risk of infection in these areas is considered low.

Diagnosis of Buruli ulcer

Buruli ulcer is usually diagnosed by a doctor, based on:

• medical history
• travel history – if you have travelled to an area associated with Buruli ulcer
• physical examination – to identify a slowly enlarging, painless ulcer
• swabs or biopsy taken from the ulcer, which are tested in a laboratory.

Early recognition and diagnosis is important to prevent skin and tissue loss. See your doctor if you have a non-healing skin lesion and ask them to consider testing for Buruli ulcer.

Incubation period of Buruli ulcer

The average incubation period is estimated to be between 4 and 5 months (Range 1 to 9 months).

Treatment for Buruli ulcer

Most Buruli ulcers require treatment with a 6 to 8 week course of specific oral antibiotics. Surgery is sometimes used in combination with antibiotic therapy if required to promote healing.

Patients with Buruli ulcer are typically cared for by Infectious Diseases specialists with experience managing this condition.

As untreated ulcers tend to get bigger with time, prompt treatment can minimise skin loss.

Prevention of Buruli ulcer

Suggestions to reduce the risk of infection include:

• Reduce mosquito breeding sites around houses and other accommodation by reducing areas where water can pool (including pot plant containers, buckets, open tins or cans, discarded tyres, and other untreated, freshwater pools).
• Mosquito proof your home by securing insect screens on accommodation.
• Avoid mosquito bites by:
  • Using personal insect repellents containing diethyltoluamide (DEET) or picaridin
  • Covering up by wearing long, loose-fitting, light-coloured clothing
  • Avoiding mosquito-prone areas and vector biting times, especially at dusk and dawn.
• When gardening, working or spending time outdoors:
  • Wear gardening gloves, long sleeved shirts and trousers
  • Wear insect repellent on any exposed skin
  • Protect cuts and abrasions with a dressing
  • Promptly wash any new scratches or cuts you receive with soap and apply a topical antiseptic and dressing.
  • Exposed skin contaminated by soil or water should be washed following outdoor activities.

More detailed advice on how to prevent mosquito bites and other tips is available.

See your doctor if you have a slow-healing skin lesion.

It is important to remember that the risk of infection is low, even in those areas where the infection is endemic (constantly present in the community).

Where to get help

• Your GP (doctor)
• Infectious disease physician
• Dermatologist