Incorporating susceptible subpopulations in microbial risk assessment: pediatric exposures to enteroviruses in river water

Abstract

The City of Stockton, California operates a wastewater treatment facility that discharges treated effluent to the San Joaquin River. During a recent discharge permit renewal, the question was raised whether pathogenic microorganisms in the effluent may cause an unacceptably high health risk for body contact recreation in the vicinity of the discharge. An investigation was initiated to characterize the risk to public health via body contact recreation in the San Joaquin River under various flow and treatment scenarios. In this investigation, a disease transmission model was applied to quantitatively characterize the relative risk associated with various treatment and flow scenarios for the City of Stockton's wastewater treatment facility. An important component of the investigation was to assess the feasibility of quantitatively characterizing the risk to highly susceptible subpopulations for effluent-related exposures to enteroviruses. This paper presents the methods used to conduct the feasibility assessment, the conclusions drawn for this project, and our recommendations to improve exposure assessments of susceptible subpopulations' contact with microbial pathogens in recreational water.

Containment of Polioviruses After Eradication and OPV Cessation: Characterizing Risks to Improve Management

“…In fresh as well as marine waters, enteroviruses present a theoretical risk from ingestion through recreational activities. ( 159 ) Assuming a spill from a vaccine facility, swimmers ingest 0.1 liter/day, ( 4 ) and the worst‐case scenario of only a one log dilution between the wastewater outlet and the recreational water source, individuals would be less at risk of an infectious dose in Helsinki (<10 CCID 50 ) than in Portland (10 4.7 CCID 50 ).…”

Do we all face the same risk when bathing in the estuary?

“…Only two quantitative studies provide epidemiological evidence that there is an increased risk of contracting enteroviral illnesses for children after swimming (D'Alessio et al, 1981;Kee et al, 1994) suggesting that the WHO guidelines mainly based on Kay et al (1994) may underestimate risks to children. Parkin et al (2003) recommended evaluation of risk by age subgroups as it may yield insights into risk factors and strategies for risk assessment modelling.…”

Role of epidemiology in microbial risk assessment

“…For example, Parkin et al (2003) analysed several studies that provided information and data on the nature, severity and extent of adverse health responses following exposure to enteroviruses in recreational water. The authors examined both the available qualitative and quantitative health data to provide a comprehensive, risk assessment-oriented evaluation on exposure of sensitive subpopulations (including children).…”