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Article

Predicting current habitat suitability for intermediate snail hosts of urogenital and intestinal schistosomiasis in the Lower Shire Valley floodplain of southern Malawi

Details

Citation

Nkolokosa C, Chirombo J, Jones CM, Mbewe RB, Kambewa EA, Makaula P, Tangena JA & Stothard JR (2025) Predicting current habitat suitability for intermediate snail hosts of urogenital and intestinal schistosomiasis in the Lower Shire Valley floodplain of southern Malawi. Parasites & Vectors, 18, Art. No.: 368. https://doi.org/10.1186/s13071-025-06952-3

Abstract
Relating the geographical distribution of intermediate freshwater snail hosts (viz. vectors of schistosomes) to local environmental attributes offers value for understanding the epidemiological landscape of schistosomiasis transmission in a changing aquatic environment. Schistosomiasis—both urogenital and intestinal—causes significant human suffering, affecting approximately 240 million people globally and grouped within the neglected tropical disease (NTD) umbrella. This study addresses the following questions: 1. Where are the most suitable habitats for intermediate host snails in the Lower Shire Valley (LSV) in Malawi? 2. Which environmental factors are strongly associated with the geographical distribution of such snails in the LSV? Methods This paper presents the first species distribution models (SDMs) for intermediate snail hosts for urogenital and intestinal schistosomiasis in Chikwawa and Nsanje Districts, which together form the LSV). The SDMs developed for this study are ensemble machine learning approaches based on Random Forest (RF), Support Vector Machines (SVM), and multilayer perceptron (MLP) and are specific to the Bulinus africanus group and Biomphalaria pfeifferi. The former transmits urogenital schistosomiasis (Schistosoma haematobium), while the latter transmits intestinal schistosomiasis (Schistosoma mansoni). Results The SDMs reveal the following: 1) currently, Bu. africanus group not only has a wide distribution across central Chikwawa and eastern Nsanje but is also concentrated in floodplains, and the LSV has few habitats that can support Bi. pfeifferi, and 2) vegetation cover is the most important predictor of Bu. africanus group distribution, whereas precipitation variables are most important for Bi. pfeifferi in the LSV. Thus, Bu. africanus group habitat is the most dominant and abundant, while Bi. pfeifferi suitable habitat is patchy and scarce. Conclusion The distribution of suitable habitats for potential urogenital and intestinal schistosomiasis transmission across LSV is not uniform and typically non-overlapping. Understanding the spatial and temporal distributions of these snails is important for controlling and eliminating schistosomiasis.

Keywords
Species distribution modelling; Ensemble machine learning; Schistosomiasis; Bulinus africanus group; Biomphalaria pfeifferi; Malawi; Climate change

Journal
Parasites & Vectors: Volume 18

StatusPublished
Funders
Publication date31/08/2025
Publication date online31/08/2025
Date accepted by journal14/07/2025
URL
PublisherSpringer Science and Business Media LLC
ISSN1756-3305

People (1)

Mr Clinton Nkolokosa

Mr Clinton Nkolokosa

Tutor, Biological and Environmental Sciences

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