Buruli ulcer is a disease caused by the bacterium Mycobacterium ulcerans. It mainly affects the skin but can also affect the bone. Cases are generally seen in the tropics, primarily in West Africa and Australia.

Infection often leads to ulcers on the arms or legs, which can also destroy skin or soft tissue. When not properly treated, the disease can cause irreversible deformity or long-term functional disability.

Buruli ulcer is found in at least 33 countries with tropical, subtropical, and temperate climates.

In 15 of these 33 countries, between 5,000 and 6,000 cases are reported every year.

Overall, most cases occur in rural communities in sub-Saharan Africa. Nearly half of those affected in Africa are children under 15 years of age.

It is not known how people get Buruli ulcer.

One possibility is that the disease is passed to humans from some insects that are found in water. While no proven link exists between human and animal infection, some animals can get the disease.

For example, laboratory tests from Victoria, Australia, confirmed the disease in several animals, including:

• Horses
• Dogs
• Alpacas
• Koalas
• Possums

The symptoms of Buruli ulcer include:

• Swelling of the skin
• Destroyed skin and soft tissue
• One or more slow growing, generally painless ulcers

People who are sick should see a doctor and get antibiotics (medicine that can help stop the disease).

If these antibiotics are not given soon after getting sick, the disease can sometimes lead to:

• Deformity
• Functional disability (such as limited joint movement)
• Bone infection
• Secondary bacterial infection of skin ulcer lesions

See a doctor if you experience the symptoms of Buruli ulcer.

Your doctor can perform tests to check for the disease.

If you have the disease, the doctor will give you antibiotics (medicine that can help stop the disease).

Be sure to follow the doctor’s instructions for taking the antibiotics.

In most cases, the disease can be treated without hospitalization.

In rare cases, surgery may be necessary to:

• Remove dead skin
• Cover skin defects
• Correct deformities

Case Definition

The World Health Organization (WHO) clinical case definition for Buruli ulcer divides the disease into two stages: active and inactive.

The active form is characterized by non-ulcerative (papules, nodules, plaques, and edema) and ulcerative disease. The distinctive features of a Buruli ulcer include:

• undermining edges
• white cotton wool-like appearance
• thickening and darkening of the skin surrounding the lesion

The ulcers are generally painless and progressive; 85% are found on the limbs, with lower limb lesions twice as common as upper limb lesions.

The inactive form is characterized by evidence of previous infection with a depressed stellate scar with or without sequelae.

Diagnosis

Buruli ulcer disease is diagnosed on the basis of the WHO clinical case definition.

Confirmation of disease is achieved through the use of two or more of the following laboratory tests:

• acid-fast bacilli (AFB) identified on microscopic smear stained by Ziehl-Neelsen technique
• polymerase chain reaction (PCR)
• histopathology
• culture

With the exception of AFB smear, these tests are not suited for use in the remote rural areas where Buruli ulcer disease occurs most frequently. Confirmation, if accomplished, typically occurs well after treatment has begun.

Depending on the patient’s age, location of lesions, pain, and geographic area, other conditions should be excluded from the diagnosis. These include

• tropical phagedenic ulcers
• chronic lower leg ulcers due to arterial and venous insufficiency (often in the older and elderly populations)
• diabetic ulcer
• cutaneous leishmaniasis
• extensive yaws

Early nodular lesions are occasionally confused with:

• boils
• lipomas
• ganglions
• lymph node tuberculosis
• onchocerciasis nodules
• other subcutaneous infections (such as fungal infection).

In Australia, papular lesions may initially be confused with an insect bite. Cellulitis may look like oedema caused by M. ulcerans infection but in the case of cellulitis, the lesions are painful and the patient is ill and febrile.

Treatment

Current WHO recommendations for treatment are as follows:

1. Different combinations of antibiotics given for eight weeks are used to treat the Buruli ulcer:
   • a combination of oral rifampicin (10 mg/kg once daily) and intravenous streptomycin (15mg/kg once daily); or
   • a combination of oral rifampicin (10 mg/kg once daily) and oral clarithromycin (7.5 mg/kg twice daily) has been used though effectiveness has not been proven by a randomized trial. Since streptomycin is contraindicated in pregnancy, the combination of rifampicin and clarithromycin is also considered the safer option for this group of patients; or
   • a combination of oral rifampicin (10 mg/kg once daily) and oral moxifloxacin (400 mg once daily) has also been used though effectiveness has not been proven by randomized trial
2. Complementary treatment, such as wound care, surgery (mainly debridement and skin grafting) and interventions to minimize or prevent disabilities, is often necessary depending on the stage of the disease.