Applied and Environmental Microbiology, July 2007, p. 4095-4099, Vol. 73, No. 13
0099-2240/07/$08.00+0 doi:10.1128/AEM.00365-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Quantitative Evaluation of the Impact of Bather Density on Levels of Human-Virulent Microsporidian Spores in Recreational Water
Thaddeus K. Graczyk,1,2,3*
Deirdre Sunderland,1
Leena Tamang,1
Timothy M. Shields,3
Frances E. Lucy,4 and
Patrick N. Breysse1
Department of Environmental Health Sciences, Division of Environmental Health Engineering,1 Johns Hopkins University Center for Water and Health,2 Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland,3 School of Science, Institute of Technology, Sligo, Ireland4
Received 14 February 2007/ Accepted 24 April 2007
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 human-virulent 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.
* Corresponding author. Mailing address: Johns Hopkins Bloomberg School of Public Health, Department of Environmental Health Sciences, 615 N. Wolfe Street, Baltimore, MD 21205. Phone: (410) 614-4984. Fax: (410) 955-0105. E-mail: tgraczyk{at}jhsph.edu
Published ahead of print on 4 May 2007.
Applied and Environmental Microbiology, July 2007, p. 4095-4099, Vol. 73, No. 13
0099-2240/07/$08.00+0 doi:10.1128/AEM.00365-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
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