# Effectiveness of Three Sampling Approaches for Optimizing Mapping and Preventive Chemotherapy against Schistosoma mansoni in the Western Part of Côte d’Ivoire

## TL;DR

This study compares three sampling methods for measuring Schistosoma mansoni infection in Côte d’Ivoire to determine the most effective and cost-efficient approach for public health planning.

## Contribution

The study evaluates three sampling strategies for Schistosoma mansoni surveillance, identifying a cost-effective approach for low-heterogeneity regions.

## Key findings

- Sampling 50% of villages provides the most accurate prevalence and intensity estimates for S. mansoni.
- Randomly selecting 15 villages in low-heterogeneity areas gives reasonable estimates at lower cost.
- Infection prevalence was 23.5%, 21.6%, and 18.3% using the three sampling approaches, respectively.

## Abstract

The elimination of schistosomiasis as a public health problem by 2030 is one of the main goals put forth in the World Health Organization’s roadmap for neglected tropical diseases. This study aimed to compare different sampling approaches to guide mapping and preventive chemotherapy. A cross-sectional parasitological survey was conducted from August to September 2022 in the health districts of Biankouma, Ouaninou, and Touba in the western part of Côte d’Ivoire. The prevalence and intensity of Schistosoma mansoni infection were assessed in children aged 5–14 years using three sampling approaches. The first approach involved a random selection of 50% of the villages in the health districts. The second approach involved a random selection of half of the villages selected in approach 1, thus constituting 25% of the villages in the health district. The third approach consisted of randomly selecting 15 villages from villages selected by approach 2 in each health district. The overall prevalence of S. mansoni was 23.5% (95% confidence interval (CI): 19.9–27.6%), 21.6% (95% CI: 17.1–26.8%), and 18.3% (95% CI: 11.9–27.1%) with the first, second, and third approach, respectively. The respective geometric mean S. mansoni infection intensity was 117.9 eggs per gram of stool (EPG) (95% CI: 109.3–127.3 EPG), 104.6 EPG (95% CI: 93.8–116.6 EPG), and 94.6 EPG (95% CI 79.5–112.7 EPG). We conclude that, although randomly sampling up to 50% of villages in a health district provides more precise population-based prevalence and intensity measures of S. mansoni, randomly selecting only 15 villages in a district characterized by low heterogeneity provides reasonable estimates and is less costly.