About the Authors

Sjoerd M. Euser

s.euser@streeklabhaarlem.nl

Affiliation Regional Public Health Laboratory Kennemerland, Haarlem, The Netherlands

Nico J. Nagelkerke

Affiliation Department of Community Medicine, United Arab Emirates University, Al-Ain, United Arab Emirates

Frank Schuren

Affiliation TNO Microbiology and Systems Biology, Zeist, The Netherlands

Ruud Jansen

Affiliation Regional Public Health Laboratory Kennemerland, Haarlem, The Netherlands

Jeroen W. Den Boer

Affiliation Regional Public Health Laboratory Kennemerland, Haarlem, The Netherlands

Competing Interests

Vitens water supply company (www.vitens.nl) has provided financial support for this study, and this does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: SE NN FS JD. Performed the experiments: SE NN FS RJ. Analyzed the data: SE NN FS RJ JD. Contributed reagents/materials/analysis tools: RJ NN. Wrote the paper: SE NN FS RJ JD.