Spatiotemporal distribution, abundance, diversity and risk of human exposure to phlebotomine sand flies, vectors of Leishmania in Belize.

BACKGROUND: Twenty-six sand fly species (Diptera: Psychodidae) are documented to occur in Belize to date, including in regions of human cutaneous leishmaniasis (CL); however, contemporary spatiotemporal compositions of sand flies and CL vectors, and the associated geographical risk of human CL, remain poorly understood. METHODS: Sand flies were sampled in six sentinel sites across a range of ecological zones between April 2023 and May 2025 using CDC light traps, human landing catches, and Biogents Sentinel traps. Specimens were morphologically identified, and spatiotemporal variations in population parameters (abundance, diversity, and vector compositions) analysed using mixed-effects general linearised models. In conjunction with recent human CL case incidence data, a Composite Exposure Risk Index (CERI) was calculated. RESULTS: A total of 7,759 sand flies representing 20 species and 10 genera were collected over two years sampling, identifying seven known Leishmania vectors. Five species, Dampfomyia deleoni, Trichophoromyia triramula, Pintomyia ovallesi, Psychodopygus panamensis, and Brumptomyia mesai, accounted for > 90% of all captures. Sand fly abundance varied significantly by sampling site and year. Species richness and diversity were highest in intact forest habitats and lowest in coastal and disturbed environments. CERI values identified areas of high to low risk of human-sand fly contact leading to clinical CL. Lutzomyia longipalpis, the principal vector of visceral leishmaniasis in the Americas, and Psathyromyia soccula, were recorded for the first time in Belize. CONCLUSIONS: This study provides a contemporary quantification of sand flies and sand fly vector spatiotemporal abundance and diversity in north-west and central-east Belize, highlighting areas of higher potential human risk of Leishmania exposure.