Assessing early detection ability through spatial arrangements in environmental surveillance for poliovirus: A...

Area of Science:

• Public Health
• Epidemiology
• Infectious Disease Surveillance

Background:

• Early detection of poliovirus circulation is critical for timely public health interventions.
• Environmental surveillance (ES) shows promise for enhanced pathogen detection.
• The impact of spatial arrangement of ES sites on early detection efficacy is not well understood.

Purpose of the Study:

• To assess the early detection capability of environmental surveillance (ES) by varying the number and location of ES sites.
• To utilize a simulation-based approach using South Africa's geographic and demographic data as a case study.
• To evaluate different strategies for ES site selection and sampling frequency.

Main Methods:

• Developed a stochastic meta-population model for unimmunized children under 5 years old.
• Simulated a single introduction of wild poliovirus serotype 1.
• Constructed six scenarios combining three importation risk distributions with two ES site layout strategies (population size-based and border crossing-based).

Main Results:

• Strategically positioned ES sites can achieve high early detection rates when importation risks are geographically confined.
• Dispersed importation risks significantly reduce the effectiveness of ES.
• Implementing ES across large areas with low sampling frequency demonstrated superior early detection ability compared to high-frequency sampling in limited areas.

Conclusions:

• The spatial arrangement and scale of environmental surveillance significantly influence early poliovirus detection.
• Broad, low-frequency sampling strategies appear more effective for diverse importation scenarios.
• Findings provide valuable insights for optimizing the scale and site selection of environmental surveillance programs.