title: Estimation of concentration ratio of indicator to pathogen-related gene in environmental water based on left-censored data.
abstract: A stochastic model for estimating the ratio between a fecal indicator and a pathogen based on left-censored data, which includes a substantially high number of non-detects, was constructed. River water samples were taken for 16 months at six points in a river watershed, and conventional fecal indicators (total coliforms and general Escherichia coli), genetic markers (Bacteroides spp.), and virulence genes (eaeA of enteropathogenic E. coli and ciaB of Campylobacter jejuni) were quantified. The quantification of general E. coli failed to predict the presence of the virulence gene from enteropathogenic E. coli, different from what happened with genetic markers (Total Bac and Human Bac). A Bayesian model that was adapted to left-censored data with a varying analytical quantification limit was applied to the quantitative data, and the posterior predictive distributions of the concentration ratio were predicted. When the sample size was 144, simulations conducted in this study suggested that 39 detects were enough to accurately estimate the distribution of the concentration ratio, when combined with a dataset with a positive rate higher than 99%. To evaluate the level of accuracy in the estimation, it is desirable to perform a simulation using an artificially generated left-censored dataset that has the identical number of non-detects as the actual data.
authors.affiliation: Department of Computer Science, Graduate School of Engineering, Gunma University, Tenjinmachi 1-5-1, Kiryu, Gunma 376-8515, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kato
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan E-mail: dsano@eng.hokudai.ac.jp.
authors.forename: Ayano
authors.initials: A
authors.lastname: Kobayashi
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan E-mail: dsano@eng.hokudai.ac.jp.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ito
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan E-mail: dsano@eng.hokudai.ac.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Miura
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan E-mail: dsano@eng.hokudai.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishii
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan E-mail: dsano@eng.hokudai.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Okabe
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan E-mail: dsano@eng.hokudai.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sano
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D000942:Antigens, Bacterial / Q000235:genetics; D001439:Bacteroides / Q000235:genetics / Q000302:isolation & purification*; D001499:Bayes Theorem; D016123:Campylobacter jejuni / Q000235:genetics / Q000302:isolation & purification*; D004755:Enterobacteriaceae / Q000235:genetics / Q000302:isolation & purification*; D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000302:isolation & purification; D004784:Environmental Monitoring / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000235:genetics; D005819:Genetic Markers; D007564:Japan; D008962:Models, Theoretical; D045483:Rivers / Q000382:microbiology*; D012621:Seasons
chemical_list: D018829:Adhesins, Bacterial; D000942:Antigens, Bacterial; C120454:CiaB protein, Campylobacter jejuni; D029968:Escherichia coli Proteins; D005819:Genetic Markers; C073819:eaeA protein, E coli