For Health Care Workers

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.