Peer-reviewed article
Assessing early detection ability through spatial arrangements in environmental surveillance for poliovirus: A simulation-based study.
Asakura TR, O'Reilly KM ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This simulation study models the placement of environmental surveillance sites for detecting poliovirus circulation in South Africa. It uses mathematical modeling to test how different numbers and locations of sampling sites affect the speed of early detection. The study finds that strategically positioned sites can detect poliovirus early when importation risks are geographically concentrated, but effectiveness decreases when risks are dispersed. The research suggests that wider geographic coverage with less frequent sampling may be more effective than intensive sampling in limited areas.
Key points
- Environmental surveillance with strategically positioned sites achieved high early detection ability under concentrated importation risk scenarios
- Dispersed importation risks reduced the effectiveness of environmental surveillance regardless of site placement
- Wide geographic coverage with low sampling frequency outperformed limited area coverage with high sampling frequency
- The study used stochastic meta-population modeling focused on unimmunized children under 5 years old
- Results have implications for deciding the scale and site selection of environmental surveillance systems
Limitations
This is a simulation-based study using modeled scenarios and assumptions about importation risks and transmission dynamics, which may not reflect real-world conditions. The findings cannot be directly applied to actual environmental surveillance implementation without further validation and consideration of practical constraints.
Abstract
Detecting the circulation of poliovirus in its early stages is paramount for swift public health action. While environmental surveillance (ES) is promising for enhancing early pathogen detection, the influence of spatial arrangement of ES sites on early detection remains unclear. Here, we aim to assess the early detection ability of ES by varying the number and location of ES sites using the simulation-based approach utilising geographic and demographic characteristics of South Africa as a case study of a non-endemic country. We developed a stochastic meta-population model among unimmunised children aged under 5 years old, assuming a single introduction of wild poliovirus serotype 1. We constructed six scenarios by combining three importation risk distributions (predicated on population size, approximations of international inbound travel volume and border crossing volume) with two ES site layout strategies (proportionate to population size and importation risks via land border crossings). We showed a modest number of strategically positioned ES sites can achieve a high early detection ability given assumed importation risks were geographically confined while dispersed importation risks reduced the effectiveness of ES. Our sensitivity analysis suggested that implementing the ES across large areas with low sampling frequency consistently resulted in a better early detection ability against various importation scenarios than implementing the ES in limited areas with high sampling frequency. Although we acknowledge the challenges of translating our simulated outcomes for real-world situations, our study has implications for deciding the scale and site selection of ES.