Estimating the probability of illness due to swimming in recreational water with a mixture of human- and gull-associated microbial source tracking markers

Brown, Kendra; Soller, Jeffrey A.; Boehm, Alexandria B.

doi:10.1039/c7em00316a

Cited by 23 publications

(30 citation statements)

References 77 publications

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“…However, direct correlations between bathers and human fecal markers have not been reported yet. Although the low levels of human marker HF183 in the surf zone waters (at the DNQ level) of this study were well below public health risk thresholds (Boehm et al, 2015;Brown et al, 2017b), there was a significant correlation between bather counts and human fecal marker HF183 for afternoon samples, especially during holidays and high visitation weekends. The human markers detected in the morning could have originated from bather shedding in the previous afternoon, but it is also possible that the WWTP outfall was influential on human marker detections due to diffuser discharge ocean circulation patterns overnight, which were unstudied.…”

Section: Discussioncontrasting

confidence: 58%

“…Modern MST typically discovers FIB sources by analyzing field samples for molecular markers that target genes of hostcoevolved or -associated bacteria, using quantitative PCR (qPCR) or droplet digital PCR (ddPCR) (Field and Samadpour, 2007;Boehm et al, 2013Boehm et al, , 2015Harwood et al, 2014;Mayer et al, 2018). Although host-associated microorganisms and related DNA markers decay in marine waters (Green et al, 2011;Ahmed et al, 2014;Mattioli et al, 2017), markers can sensitively and specifically reveal hosts' wastes, and allow for quantitative microbial risk assessment (QMRA) (Boehm et al, 2015;Brown et al, 2017b). As such, host-associated fecal markers such as the human fecal marker HF183 targeting bacteria closely related to Bacteroides dorei have been widely applied in numerous MST studies (Bernhard and Field, 2000;Field and Samadpour, 2007;Boehm et al, 2013Boehm et al, , 2015Harwood et al, 2014;Mayer et al, 2018), with their use now mainstream as an EPAvalidated method.…”

Section: Introductionmentioning

confidence: 99%

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Bather Shedding as a Source of Human Fecal Markers to a Recreational Beach

Werfhorst

Steets

et al. 2021

Front. Microbiol.

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Microbial source tracking (MST) can identify and locate surf zone fecal indicator bacteria (FIB) sources. However, DNA-based fecal marker results may raise new questions, since FIB and DNA marker sources can differ. Here, during 2 years of summertime (dry season) MST for a Goleta, California recreational beach, surf zone FIB were mainly from gulls, yet low level human-associated DNA-based fecal marker (HF183) was detected in 25 and 14% of surf zone water samples, respectively. Watershed sources were hypothesized because dry weather creek waters had elevated FIB, and runoff-generating rain events mobilized human (and dog) fecal markers and Salmonella spp. into creeks, with human marker HF183 detected in 40 and 50% of creek water samples, dog markers detected in 70 and 50% of samples, and Salmonella spp. in 40 and 33.3% of samples, respectively over 2 years. However, the dry weather estuary outlet was bermed in the first study year; simultaneously, creek fecal markers and pathogens were lower or similar to surf zone results. Although the berm breached in the second year, surf zone fecal markers stayed low. Watershed sediments, intertidal beach sands, and nearshore sediments were devoid of HF183 and dog-associated DNA markers. Based on dye tests and groundwater sampling, beach sanitary sewers were not leaking; groundwater was also devoid of HF183. Offshore sources appeared unlikely, since FIB and fecal markers decreased along a spatial gradient from the surf zone toward nearshore and offshore ocean waters. Further, like other regional beaches, surf zone HF183 corresponded significantly to bather counts, especially in the afternoons when there were more swimmers. However, morning detections of surf zone HF183 when there were few swimmers raised the possibility that the wastewater treatment plant (WWTP) offshore outfall discharged HF183 overnight which transported to the surf zone. These findings support that there may be lowest achievable limits of surf zone HF183 owing to several chronic and permanent, perhaps diurnal, low concentration sources.

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Section: Discussioncontrasting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Bather Shedding as a Source of Human Fecal Markers to a Recreational Beach

Werfhorst

Steets

et al. 2021

Front. Microbiol.

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“…This low variability across sewage samples is highly relevant for the future application of genetic MST modeling approaches such as source apportionment 23 , 34 or the support of quantitative microbial risk assessment (QMRA). 28 , 35 , 36 …”

Section: Discussionmentioning

confidence: 99%

Global Distribution of Human-Associated Fecal Genetic Markers in Reference Samples from Six Continents

Mayer

Reischer

Ixenmaier

et al. 2018

Environ. Sci. Technol.

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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.

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“…To our knowledge, this is the first study comparing GFD concentrations in a tidal river. Enterococci originating from avian‐fecal contamination may pose less risk to public health (Brown et al, 2017); therefore, identifying the source of high enterococci levels during a routine monitoring study has implications on recreational water use advisories.…”

Section: Resultsmentioning

confidence: 99%

“…Identifying the source of enterococci in the environment is particularly important because non‐human sources such as wildlife may cause overestimation of the health risk associated with human exposure (Brown et al, 2017). With the recent advent of quantitative polymerase chain reaction (qPCR), sources of contamination can be identified using library‐independent microbial source tracking methods.…”

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confidence: 99%

The Impact of Tides on Microbial Water Quality at an Inland River Beach

2018

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Most coastal freshwater ecosystems in the United States have semi‐tidal movements during the day. Routine monitoring of these environments is conducted once during the day when tides can be at either ebb or flood conditions, causing a variability in bacterial concentrations and misinterpretation of the illness risk associated with human activities. The occurrence and levels of enterococci (enterococci 23S rDNA [Ent23S]) and human‐ (HF183) and avian‐ (GFD) associated microbial source tracking (MST) markers were investigated using quantitative polymerase chain reaction (qPCR) along with detection of culturable enterococci and environmental parameters. Samples were collected during flood and ebb tide conditions (May–September) from a tidal river used for recreational activities. Culturable enterococci [t(420) = 2.093, p = 0.040] and Ent23S [t(420) = 2.243, p = 0.028] controlled for tide type were significantly different; higher enterococci concentrations were detected during the flood tide. Among all samples, 6% were positive for HF183, and GFD was positively correlated with Ent23S (r = 0.92, p = 0.029) and conductivity (r = 0.93, p = 0.023) during flood tide. Unlike the general assumption that ebb tide flow in a river would likely carry runoff from the land, the microbial contaminants in this case were transported from upstream via ocean water to the river during the flood tide. These results suggest that hydrology and land use patterns must be considered in sampling design when conducting future microbial water quality monitoring programs to better characterize recreational water safety in tidal rivers. Core Ideas Ocean water was carrying high enterococci into the river during flood tide. Low concentrations of HF183 occurred in 6% of the samples only during flood tide. Avian‐associated pollution was detected in 40% of the samples during both tides.

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Estimating the probability of illness due to swimming in recreational water with a mixture of human- and gull-associated microbial source tracking markers

Cited by 23 publications

References 77 publications

Bather Shedding as a Source of Human Fecal Markers to a Recreational Beach

Bather Shedding as a Source of Human Fecal Markers to a Recreational Beach

Global Distribution of Human-Associated Fecal Genetic Markers in Reference Samples from Six Continents

The Impact of Tides on Microbial Water Quality at an Inland River Beach

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