Suspected Buruli ulcer cases in Tonkolili District, Sierra Leone– a prospective cohort study

Purpose: There is a high burden of chronic ulcers in Sierra Leone. However, (early) diagnosis and treatment are challenging. Data on endemicity of Mycobacterium ulcerans is limited to WHO reports from 2008 to 2011. Methods: Patients presenting with wounds at Masanga Teaching Hospital were included in a prospective cohort study and scored following the WHO clinical list for Buruli ulcer (BU). Wounds were screened for M. ulcerans by selective culture on solid and liquid media and loop-mediated isothermal amplification (LAMP) of the M. ulcerans specific IS2404. Results: Between July 2019 and November 2020, 159 patients were included. The median age was 41 years (range: 2–92), 34% (54/159) were female and 56% (89/159) were literate. The median duration of a wound before admission was 12 months (range: 0-720 months), 87% (137/159) of lesions were below the knee. Wounds of 37% (58/159) of the patients were clinically scored as ‘(very) likely to be Buruli ulcer’. Seven out of 72 patients tested by LAMP were positive for IS2404, two showed specific melting curves. None of the wound swabs yielded a positive culture for M. ulcerans. Ninety-eight (62%) patients had a wound-related surgery during this study, 101 (63%) of patients were improving or healed at the time of discharge. Conclusions: The prevalence of BU based on the WHO scoring system is high in Sierra Leone. National and international awareness, training of healthcare workers, development of in-country bacteriology as well as the furthering of robust molecular and immunological assays could reduce the burden of this neglected tropical disease.