Relationships between Microbial Indicators and Pathogens in Recreational Water Settings

Area of Science:

• Environmental microbiology
• Water quality assessment
• Public health

Background:

• Fecal pollution in recreational waters poses risks to public health and causes aesthetic issues.
• Current indicators like fecal indicator bacteria (FIB) and alternative markers are general and may not fully inform risk assessments.
• Microbial source tracking (MST) markers can identify specific fecal pollution sources.

Purpose of the Study:

• To review the relationship between various fecal indicators and pathogen groups over 40 years of research.
• To evaluate the statistical significance and consistency of these relationships in different water types and conditions.
• To assess the suitability of current indicators for informing risk assessment and remediation strategies.

Main Methods:

• Systematic review of 73 scientific papers published over 40 years.
• Analysis of reported relationships between indicators (FIB, alternative, MST) and pathogen groups.
• Examination of statistical significance, water type (freshwater vs. marine), weather events, and detection frequencies.

Main Results:

• Nearly half of the reviewed studies lacked statistical analysis.
• Statistically significant relationships were more common in freshwater than marine/brackish waters.
• Fecal indicator bacteria (FIB) showed stronger associations with pathogenic bacteria/protozoa than viruses, with detection frequency and concentration generally higher for FIB than other indicators.

Conclusions:

• While FIB, alternative indicators, and MST markers indicate fecal pollution, their link to waterborne pathogens, particularly viruses, is often weak and inconsistent.
• The relationship is influenced by detection rates, shedding variability, environmental fate, and site-specific contamination complexities.
• Improvements in risk assessment and remediation require a nuanced understanding of indicator performance and limitations.