Temporal dynamics of schistosomiasis transmission in an endemic agricultural landscape of central Sulawesi, Indonesia

Abstract

Background: Schistosomiasis remains endemic in Central Sulawesi, Indonesia, where transmission is closely associated with agricultural landscapes that support the intermediate host snail Oncomelania hupensis lindoensis. Despite ongoing control efforts, sustained transmission interruption has not yet been achieved. Aim: This study assessed temporal and epidemiological trends of schistosomiasis transmission in Napu Valley, Central Sulawesi, using routine surveillance data collected between 2017 and 2023. Methods: Data included the number of snail habitats, snail density in agricultural land, and prevalence of schistosomiasis among farmers. Temporal patterns were examined descriptively, and associations between ecological indicators and human infection were explored using Spearman correlation. Results: Snail habitats persisted throughout the study period with evidence of reexpansion after earlier reductions. Snail density remained relatively low from 2017 to 2020 but increased markedly after 2021, particularly in plantation-dominated areas. The prevalence of schistosomiasis declined to its lowest levels during 2019–2020 but increased again from 2021 onward, with the highest village-level prevalence occurring in Dodolo (7.22%) in 2022 and in Wanga (7.19%) in 2023. Correlation analysis suggested a moderate positive lagged association between snail density and prevalence in the following year, although this relationship was not statistically significant. Conclusion: Schistosomiasis transmission in the Napu Valley of Central Sulawesi persists within dynamic agricultural ecosystems that sustain populations of O. hupensis lindoensis, highlighting the need for integrated One Health strategies combining chemotherapy, environmental management, and agricultural water interventions to achieve sustainable transmission control.