Diagnosis

Diagnosis requires clinical suspicion in the presence of a history of travel to or residence in an endemic area. The median incubation period is 4.5 months.

Rapid and accurate diagnosis can be made directly from tests of a swab run around the undermined edge of an ulcer. It is important to order the correct tests—M. ulcerans-specific polymerase chain reaction (PCR), smear and culture. Many lesions are smear-positive; culture results may take several weeks.

In cases presenting without a defined ulcer (eg atypical cellulitis, oedema, plaque), the diagnosis is suggested by history of exposure to an endemic area and failure to respond to usual empirical treatment. If M. ulcerans infection is suspected, perform a biopsy or fine-needle aspirate for testing. Clearly record the possibility of M. ulcerans on the test request form—M. ulcerans-specific PCR is very likely to be positive, and histology is characteristic.