Cutaneous leishmaniasis in British troops following jungle training in Belize: cumulative incidence and potential risk practices

Abstract

AbstractIntroductionBritish soldiers undergoing jungle training (JT) in Belize typically experience a relatively low risk of developing cutaneous leishmaniasis (CL). However, an uncharacteristically large outbreak of CL occurred in 2022. This study aimed to determine the cumulative incidence (CUMI) of the disease and highlight potential shortcomings in personal protective measures (PPMs) to mitigate exposure to sand fly vector bites.MethodsA retrospective analysis was conducted on medical records of CL cases between 2005 and 2022, as well as on questionnaire responses regarding PPMs administered to CL cases in 2022. Data were sourced from Defence Public Health Unit, Military Environmental Health Department and British Army Training Support Unit Belize.ResultsEighty-one confirmed clinical CL cases were recorded between 2005 and 2022, with a substantial peak (38 cases) in 2022. Most cases occurred during the wet season. Pre-2022, the median CUMI per 8-week deployment was 0.90% (Q1–Q3: 0.34%–1.34%), with an annual variation of 0.2% to 2.0%. In 2022, the CUMI spiked to 4.22%, associated with a risk ratio of 5.3 (95% C.I.s: 3.41, 8.16), and rising to a CUMI of 7.3% in a single unit of 450 men (33 CL cases) in late 2022. These values are significantly higher than the median CUMI of all previous years, and to published reports for other CL-endemic regions. Troop responses identified limitations in the supply of optimal equipment, and in sand fly bite and leishmaniasis risk avoidance information provided by the pre-deployment health education (PDHE) programme. Compliance with PDHE advise was also suboptimal, with irregular use of insect repellents, protective clothing / head netting, and insecticide-treated hammocks.ConclusionsThe reasons behind the unusually high numbers of CL cases and CUMI in 2022 remain unclear, emphasising the need to improve PPM provision and implement a comprehensive PDHE programme for troops undergoing JT in Belize.