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Coliphages as indicators of gastrointestinal illness in recreational waters: a pooled analysis of six prospective marine beach cohorts
Citation:
Benjamin-Chung, J., B. Arnold, Tim Wade, K. Schiff, J. Griffith, S. Weisberg, AND J. Colford. Coliphages as indicators of gastrointestinal illness in recreational waters: a pooled analysis of six prospective marine beach cohorts. Presented at EPA 2016 Recreational Waters Conference, New Orleans, LA, April 12 - 15, 2016.
Impact/Purpose:
A pooled analysis of several studies was conducted to investigate the association between a surrogate of viral contamination (coliphage) and swimming associated illness
Description:
Background: Coliphages have been proposed as potential indicators of fecal contamination of marine recreational waters because they may better predict the presence of viruses than fecal indicator bacteria. We estimated the association between the presence of coliphages and self-reported gastrointestinal illness. Methods: We pooled data from six prospective cohort studies conducted from 2003 to 2009 that enrolled beachgoers in the summer at coastal beaches in California, Alabama, and Rhode Island. Studies collected water samples and recorded incident gastrointestinal illness within 10 days of the beach visit. Samples were tested for male-specific and somatic coliphage using EPA methods 1601 and 1602. We estimated cumulative incidence ratios (CIR) for the association between gastrointestinal illness and coliphage when human fecal pollution was suspected to be present (“high-risk conditions”) and not present (“low-risk conditions”). Results: Under high-risk conditions, a 1-log10 increase in male-specific coliphage levels was associated with a CIR of 1.30 (95% CI 0.94, 1.81) (EPA 1601; n=6 beaches) and 2.20 (95% CI 1.30, 3.71) (EPA 1602; n=2 beaches); under low-risk conditions the CIRs were 0.83 (95% 0.70, 1.00) (EPA 1601) and 0.71 (95% 0.19, 2.72) (EPA 1602). The CIRs for a 1-log10 increase in somatic coliphage (EPA 1602) were 1.27 (95% CI 0.92, 1.76) under high-risk conditions and 0.98 (95% 0.82, 1.16) under low-risk conditions (n=2 beaches). Conclusion: The presence of coliphage was associated with increased gastrointestinal illness risk at beaches with suspected human fecal pollution.This abstract does not represent EPA policy