The spatial distribution of Schistosoma mansoni infection in four regions of western Côte d’Ivoire

Abstract

Schistosomiasis poses a considerable public health burden in subSaharan Africa and a sound understanding of the spatial distribution facilitates to better target control interventions. The objectives of this study were i) to assess the prevalence of Schistosoma mansoni among school-aged children in four regions of western Côte d'Ivoire; ii) to determine demographic, climatic and environmental factors that influence the distribution of S. mansoni; and iii) to map and predict the distribution of S. mansoni in non-sampled locations. Parasitological surveys were carried out in 264 schools from June to December 2011. In each school, we aimed to examine 50 children for S. mansoni infection using duplicate Kato-Katz thick smears. Schools were georeferenced using a hand-held global positioning system receiver. Demographic data were obtained from readily available school lists, while climatic and environmental data were extracted from open-access remote sensing databases. Multivariable, binary non-spatial models and a Bayesian geostatistical logistic regression model were used to identify demographic, climatic and environmental risk factors for S. mansoni infection. Risk maps were developed based on observed S. mansoni prevalences and using Bayesian geostatistical models to predict prevalences at non-sampled locations. Overall, 12,462 children provided a sufficiently large stool sample to perform at least one Kato-Katz thick smear. The observed overall prevalence of S. mansoni infection was 39.9%, ranging from 0 to 100% at the unit of the school. Bayesian geostatistical analysis revealed that age, sex, altitude and difference between land surface temperature at day and night were significantly associated with S. mansoni infection. The S. mansoni risk map presented here is being been used by the national schistosomiasis control programme for spatial targeting of praziquantel and other interventions.

Sustaining the Control of Schistosoma mansoni in Western Côte d'Ivoire: Baseline Findings Before the Implementation of a Randomized Trial

“…[33][34][35][36][37] Third, our results confirm that schistosomiasis is a focal disease; indeed, the prevalence of infection at the unit of the school showed considerable variation from one school to another. 29 Focality of S. mansoni is often explained with special occupational or recreational risk behaviors, proximity to open freshwater bodies that serve as habitat for intermediate host snails, and access to, and use of, sanitation facilities. [38][39][40][41][42] In our study, for example, boys showed a higher infection prevalence than girls.…”

“…S. mansoni prevalence rates above 24% were mainly observed in Tonkpi region, while schools with prevalence of infection ranging between 10% and 24% were predominantly found in Gomon, Cavally, and Haut-Sassandra. 29 Those 75 villages where the S. mansoni prevalence ranged between 10% and 24% and that fulfilled other inclusion criteria were eligible for the SCORE trial. Villages were randomized into one of three treatment arms.…”

Análise multivariada da esquistossomose no estado de Minas Gerais: análise de componentes principais

“…A relação negativa com a altitude coincide com alguns trabalhos, como exemplo, em recente artigo avaliando a esquistossomose em Costa do Marfim (África), utilizando metodologia de distribuição espacial da parasitose identificou-se uma relação negativa entre a altitude e a ocorrência da esquistossomose, sendo aquela a região mais propicia para tal ocorrência, visto que está situada entre 200 e 300 metros de altitude 19 .…”

Comparison of the spatial patterns of schistosomiasis in Zimbabwe at two points in time, spaced twenty-nine years apart: is climate variability of importance?

“…These predictions can be displayed as smoothed risk maps and serve as a decision support tool for health planning and control (Raso et al, 2005;Simoonga et al, 2009;Woodhall et al, 2013;Assare et al, 2015). However, due to the central role of climate, the spatial distribution of schistosomiasis might change in the future with anticipated climate change (McCreesh and Booth, 2013).…”