Epidemiological Patterns of Leishmaniasis in Two Northeastern Algerian Wilayas: A Comparative Study of Environmental and Climatic Factors

Abstract

INTRODUCTION: Leishmaniasis remains a neglected tropical disease in Algeria, where both cutaneous (CL) and visceral (VL) forms persist despite ongoing control efforts. Understanding the epidemiological patterns and environmental drivers of transmission is essential for improving surveillance and control strategies. METHODS: This study analysed 379 human cases (363 CL and 16 VL) reported between 2014 and 2024 in the northeastern provinces of Skikda and Constantine. Epidemiological data were integrated with climatic and environmental variables using geographic information systems (GIS) and statistical analyses to identify spatial and temporal patterns of disease distribution. RESULTS: CL accounted for 95.8% of cases and predominantly affected young adults aged 20-44 years, with incidence peaking in late autumn and early winter. In contrast, VL was exclusively observed in children under 9 years of age. Spatial analysis showed that both forms were strongly associated with low altitudes (≤ 900 m for CL and 300-600 m for VL), gentle slopes (≤ 3%), and human-modified landscapes such as croplands and grasslands. Conversely, dense forests, wetlands, bare soils, and steep terrains appeared to act as natural barriers to transmission. Climatic correlations were generally weak and not statistically significant, except for a positive association between CL incidence and relative humidity and wind speed in Skikda, and a negative association with soil moisture in Constantine. CONCLUSION: These findings highlight the important role of microclimatic, topographic, and land-use factors in shaping leishmaniasis transmission dynamics. The study provides a spatial framework that can support targeted surveillance and integrated vector control strategies in endemic regions.