Improving clinical and epidemiological predictors of Buruli ulcer

Chronic wounds in Sierra Leone: Searching for Buruli ulcer, a NTD caused by Mycobacterium ulcerans, at Masanga Hospital

Background

Chronic wounds pose a significant healthcare burden in low- and middle-income countries. Buruli ulcer (BU), caused by Mycobacterium ulcerans infection, causes wounds with high morbidity and financial burden. Although highly endemic in West and Central Africa, the presence of BU in Sierra Leone is not well described. This study aimed to confirm or exclude BU in suspected cases of chronic wounds presenting to Masanga Hospital, Sierra Leone.

Methodology

Demographics, baseline clinical data, and quality of life scores were collected from patients with wounds suspected to be BU. Wound tissue samples were acquired and transported to the Swiss Tropical and Public Health Institute, Switzerland, for analysis to detect Mycobacterium ulcerans using qPCR, microscopic smear examination, and histopathology, as per World Health Organization (WHO) recommendations.

Findings

Twenty-one participants with wounds suspected to be BU were enrolled over 4-weeks (Feb-March 2019). Participants were predominantly young working males (62% male, 38% female, mean 35yrs, 90% employed in an occupation or as a student) with large, single, ulcerating wounds (mean diameter 9.4cm, 86% single wound) exclusively of the lower limbs (60% foot, 40% lower leg) present for a mean 15 months. The majority reported frequent exposure to water outdoors (76%). Self-reports of over-the-counter antibiotic use prior to presentation was high (81%), as was history of trauma (38%) and surgical interventions prior to enrolment (48%). Regarding laboratory investigation, all samples were negative for BU by microscopy, histopathology, and qPCR. Histopathology analysis revealed heavy bacterial load in many of the samples. The study had excellent participant recruitment, however follow-up proved difficult.

Conclusions

BU was not confirmed as a cause of chronic ulceration in our cohort of suspected cases, as judged by laboratory analysis according to WHO standards. This does not exclude the presence of BU in the region, and the definitive cause of these treatment-resistance chronic wounds is uncertain.

Chronic wounds constitute a significant surgical burden to low- and middle-income countries; however, their aetiology often remains poorly understood. This study improves our understanding of wound aetiology through tissue analysis of chronic leg wounds suspected to be caused by Buruli ulcer (BU). BU is a neglected tropical disease caused by infection with Mycobacterium ulcerans, and remains severely under-researched. There is a lack of testing facilities in regions surrounding endemic countries which makes prevalence difficult to determine, with a particular paucity of data from Sierra Leone (SL). This study identified twenty-one patients with wounds suspected to be caused by BU who presented to Masanga Hospital (Tonkonili District, Sierra Leone) between February and March 2019. Tissue samples were acquired from the wounds and transported to a European tropical health laboratory for analysis. Significant bacterial loads were demonstrated in the samples. However, the gold-standard molecular tests recommended by World Health Organisation (WHO) revealed no cases of BU. These results suggest that BU is not a major cause of chronic wounds in the Northern Province of Sierra Leone. Our conclusions cannot necessarily be generalised to other regions of Sierra Leone, therefore further studies in other geographical districts are required.