Abstract
Numerous bacterial genetic markers are available for the molecular detection of human sources of fecal pollution in environmental waters. However, widespread application is hindered by a lack of knowledge regarding geographical stability, limiting implementation to a small number of well-characterized regions. This study investigates the geographic distribution of five human-associated genetic markers (HF183/BFDrev, HF183/BacR287, BacHum-UCD, BacH, and Lachno2) in municipal wastewaters (raw and treated) from 29 urban and rural wastewater treatment plants (750–4 400 000 population equivalents) from 13 countries spanning six continents. In addition, genetic markers were tested against 280 human and nonhuman fecal samples from domesticated, agricultural and wild animal sources. Findings revealed that all genetic markers are present in consistently high concentrations in raw (median log10 7.2–8.0 marker equivalents (ME) 100 mL–1) and biologically treated wastewater samples (median log10 4.6–6.0 ME 100 mL–1) regardless of location and population. The false positive rates of the various markers in nonhuman fecal samples ranged from 5% to 47%. Results suggest that several genetic markers have considerable potential for measuring human-associated contamination in polluted environmental waters. This will be helpful in water quality monitoring, pollution modeling and health risk assessment (as demonstrated by QMRAcatch) to guide target-oriented water safety management across the globe.
Highlights
The disease burden from poor water quality, sanitation, and hygiene is estimated to be responsible for up to 4% of all deaths worldwide.[1,2] Limited access to safe drinking water has led the World Health Organization to develop strategies for managing water quality with the goal to protect and promote human health.[3]
All quantitative real-time PCR (qPCR) data were expressed as log[10] (x + 1), where x is the calculated concentration before applying the logarithm to it
Human-Associated Genetic Markers Are Widely Distributed Across the World
Summary
The disease burden from poor water quality, sanitation, and hygiene is estimated to be responsible for up to 4% of all deaths worldwide.[1,2] Limited access to safe drinking water has led the World Health Organization to develop strategies for managing water quality with the goal to protect and promote human health.[3]. A useful MST assay should have high source-specificity (low number of false positives) and excellent source-sensitivity (low number of false negatives).[7] MST assay specificity and sensitivity are typically evaluated based on repeated testing of reference fecal and wastewater samples often collected in close proximity to the research laboratory.[8−11] For example, Boehm et al (2013) evaluated specificity and sensitivity of 41 MST methods with more than 100 reference samples collected from the California area.[12] To date, the performance of many MST assays described in the literature have not been tested for sourcespecificity and -sensitivity beyond the regional level.[8,13−15] For this reason, it is often difficult to identify the most appropriate methods when planning a MST application in a new geographical area. The study emphasized the investigation of the quantitative distribution of genetic marker concentrations in the target and nontarget fecal samples in order to fully assess performance
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