Variations in microbial indicator densities in beach waters and health-related assessment of bathing water quality

Cheung, Waiman; Chang, K. C. K.; Hung, Richard

doi:10.1017/s0950268800048482

Cited by 39 publications

(24 citation statements)

References 9 publications

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“…comm.). The relationship between bather density and staphylococci was confirmed in an extensive study of Hong Kong beaches (Cheung et al 1991), where Escherichia coli was used to monitor faecal pollution. Thus, streptococci may still be a superior indicator of sewage contamination.…”

Section: Alternatives To Faecal Streptococcimentioning

confidence: 82%

Faecal streptococci as faecal pollution indicators: A review. Part II: Sanitary significance, survival, and use

Sinton

Donnison²,

Hastie

1993

New Zealand Journal of Marine and Freshwater Research

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Some New Zealand regional councils are examining the use of faecal streptococci (or the subset, enterococci) to assist in identifying pollution sources, or as better indicators of disease risk in bathing waters than faecal coliforms. However, in spite of worldwide investigation, faecal streptococci have largely failed to fulfil their potential as pollution source (human versus animal) indicators in receiving waters. Many qualifications accompany the use of faecal coliform : faecal streptococci (FC : FS) ratios, and the species identification approach (using biochemical and DNA-based methods) has produced inconclusive results. Nevertheless, the FC : FS shift method (in which the ratio changes under sample storage) may M92025 Received 6 May 1992 ; accepted 18 January 1993 warrant further investigation. Although reported results vary widely, most studies indicate that faecal streptococci outlive faecal coliforms in receiving waters and are more resistant to sunlight-induced inactivation. USEPA epidemiological studies showed that enterococcus concentrations were better correlated than faecal conform concentrations with disease risk associated with bathing in sewage-polluted waters. These results, which implied that the enterococci better represented viral hazard, led the USEPA to recommend the use of enterococci (or Escherichia coli in freshwaters) as bathing water quality indicators. These recommendations have largely been followed in provisional New Zealand Department of Health guidelines. However, adoption of the USEPA criteria should be approached cautiously, because of doubts about their epidemiological applicability in New Zealand, and a lack of information about streptococcal concentrations and species profiles in local effluents and receiving waters.

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Section: Alternatives To Faecal Streptococcimentioning

confidence: 82%

Faecal streptococci as faecal pollution indicators: A review. Part II: Sanitary significance, survival, and use

Sinton

Donnison²,

Hastie

1993

New Zealand Journal of Marine and Freshwater Research

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“…Each enterococcus count is applied to a uniform risk level for an entire day in the model. Illness rate estimates may be affected by fluctuations of indicator level throughout the day (20)(21)(22). Furthermore, a reanalysis of the results of Cabelli et al (5) by other researchers suggested the possibility of underestimating true HCGI risk by 14-57% (21).…”

Section: Environmental Medicine | Modeling Bathing Patterns and Gastrmentioning

confidence: 99%

Evaluation of recreational health risk in coastal waters based on enterococcus densities and bathing patterns.

Turbow

Osgood

Jiang

2003

Environ Health Perspect

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We constructed a simulation model to compute the incidences of highly credible gastrointestinal illness (HCGI) in recreational bathers at two intermittently contaminated beaches of Orange County, California. Assumptions regarding spatial and temporal bathing patterns were used to determine exposure levels over a 31-month study period. Illness rates were calculated by applying previously reported relationships between enterococcus density and HCGI risk to the exposure data. Peak enterococcus concentrations occurred in late winter and early spring, but model results showed that most HCGI cases occurred during summer, attributable to elevated number of exposures. Approximately 99% of the 95,010 illness cases occurred when beaches were open. Model runs were insensitive to 0-10% swimming activity assumed during beach closure days. Comparable illness rates resulted under clustered and uniform bather distribution scenarios. HCGI attack rates were within federal guidelines of tolerable risk when averaged over the study period. However, tolerable risk thresholds were exceeded for 27 total days and periods of at least 6 consecutive days. Illness estimates were sensitive to the functional form and magnitude of the enterococcus density-HCGI relationships. The results of this study contribute to an understanding of recreational health risk in coastal waters.

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“…Fecal coliforms in recreational bathing waters can originate from the resuspension of bottom sediments (2,30,33,43) and from the bathers themselves (7,11,17,23,31,44). On average, the anal fecal residue being washed off to the water by a recreational bather varies from 0.14 to 10 g (23), and a load of 6 ϫ 10 6 CFU of enterococci can be shed by an average recreational bather during a 15-min immersion (17).…”

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confidence: 99%

“…However, whether the sediment resuspension or the bather microbial input played a more important role in elevated spore levels is not determined. Usually, both mechanisms are responsible for the elevated fecal coliform counts in bathing waters (7,11,17,23,31,44), and investigation of these mechanisms' impacts on microsporidian pores requires further research.…”

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confidence: 99%

Quantitative Evaluation of the Impact of Bather Density on Levels of Human-Virulent Microsporidian Spores in Recreational Water

Graczyk

Sunderland

Tamang

et al. 2007

Appl Environ Microbiol

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Microsporidial gastroenteritis, a serious disease of immunocompromised people, can have a waterborne etiology. During summer months, samples of recreational bathing waters were tested weekly for humanvirulent microsporidian spores and water quality parameters in association with high and low bather numbers during weekends and weekdays, respectively. Enterocytozoon bieneusi spores were detected in 59% of weekend (n ‫؍‬ 27) and 30% of weekday (n ‫؍‬ 33) samples, and Encephalitozoon intestinalis spores were concomitant in a single weekend sample; the overall prevalence was 43%. The numbers of bathers, water turbidity levels, prevalences of spore-positive samples, and concentrations of spores were significantly higher for weekend than for weekday samples; P values were <0.001, <0.04, <0.03, and <0.04, respectively. Water turbidity and the concentration of waterborne spores were significantly correlated with bather density, with P values of <0.001 and <0.01, respectively. As all water samples were collected on days deemed acceptable for bathing by fecal bacterial standards, this study reinforces the scientific doubt about the reliability of bacterial indicators in predicting human waterborne pathogens. The study provides evidence that bathing in public waters can result in exposure to potentially viable microsporidian spores and that body contact recreation in potable water can play a role in the epidemiology of microsporidiosis. The study indicates that resuspension of bottom sediments by bathers resulted in elevated turbidity values and implies that the microbial load from both sediments and bathers can act as nonpoint sources for the contamination of recreational waters with Enterocytozoon bieneusi spores. Both these mechanisms can be considered for implementation in predictive models for contamination with microsporidian spores.

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Variations in microbial indicator densities in beach waters and health-related assessment of bathing water quality

Cited by 39 publications

References 9 publications

Faecal streptococci as faecal pollution indicators: A review. Part II: Sanitary significance, survival, and use

Faecal streptococci as faecal pollution indicators: A review. Part II: Sanitary significance, survival, and use

Evaluation of recreational health risk in coastal waters based on enterococcus densities and bathing patterns.

Quantitative Evaluation of the Impact of Bather Density on Levels of Human-Virulent Microsporidian Spores in Recreational Water

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