Modeling Biphasic Environmental Decay of Pathogens and Implications for Risk Analysis
Andrew F Brouwer1, Marisa C Eisenberg1, Justin V Remais2
1Department of Epidemiology, University of Michigan , 1415 Washington Heights, Ann Arbor, Michigan 48109, United States.
Environmental Science & Technology
|January 24, 2017
Summary
Pathogen decay in the environment often shows a fast then slow pattern, not just simple exponential decay. Understanding these biphasic dynamics is crucial for accurate environmental health risk assessment.
Area of Science:
- Environmental microbiology
- Infectious disease ecology
- Mathematical modeling of biological systems
Background:
- Environmental factors significantly influence infectious disease transmission.
- Traditional models of pathogen decay (e.g., exponential decay) may oversimplify real-world dynamics.
- Growing recognition of biphasic pathogen decay (fast followed by slow) necessitates more complex models.
Purpose of the Study:
- To investigate the mechanisms driving biphasic pathogen decay dynamics.
- To assess the identifiability of models incorporating population heterogeneity, hardening off, and viable-but-not-culturable states.
- To evaluate the impact of biphasic decay on environmental health risk assessments.
Main Methods:
- Developed a general mathematical model encompassing multiple mechanisms for biphasic decay.
- Employed a differential algebra approach to identify parameter combinations from longitudinal data.
- Conducted case studies using Cryptosporidium and Escherichia coli concentrations.
Main Results:
- Biphasic decay dynamics can arise from various mechanisms beyond simple population heterogeneity.
- Models were not fully identifiable from longitudinal data alone, but identifiable parameter combinations were determined.
- Failure to account for biphasic dynamics led to significant under- or overestimation of disease risks and pathogen levels in case studies.
Conclusions:
- Biphasic pathogen die-off is a critical phenomenon in environmental risk assessment.
- Improved understanding of biphasic decay mechanisms enhances the reliability of environmental hazard models.
- Accurate modeling of pathogen fate and transport is essential for mitigating exposure and controlling infectious diseases.
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