Adenovirus-associated health risks for recreational activities in a multi-use coastal watershed based on site-specific quantitative microbial risk assessment

• Published in: Water research (Oxford) Vol. 47; no. 16; pp. 6309 - 6325
• Main Authors: Kundu, Arti, McBride, Graham, Wuertz, Stefan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.10.2013; Elsevier
• Subjects: Adenoviridae; Adenoviridae - genetics; Adenoviridae - physiology; Adenovirus; adults; Applied sciences; Bacteria; children; coliform bacteria; Computer simulation; Contact; Criteria; Enterovirus; Enterovirus - genetics; Enterovirus - physiology; Escherichia coli; Exact sciences and technology; gastrointestinal system; genome; Genomes; guidelines; Human enterovirus; Human health; Humans; Illnesses; indicator species; ingestion; microbiological risk assessment; Monte Carlo method; Pollution; primary contact; public health; quantitative polymerase chain reaction; Recreation; Recreational waters; Risk; Risk Assessment; secondary contact; viruses; Water Microbiology; water quality; Water treatment and pollution; Watersheds; United States; North America; America; USA; Recreational waters; Human health; Adenovirus; Risk assessment; Adenoviridae; Microbiology; Picornaviridae; Enterovirus; Coastal zone; Adenovirus 4; Adenovirus 3; Health and environment; Human adenovirus; Pathogenic; Watershed; Bacteria; Feces; Biological contamination; Public health; Monte Carlo method; Quality criterion; Biological indicator; Coliforms; Real time system; Virus; Polymerase chain reaction; Surveillance; DNA; Water quality; Health hazards; Mastadenovirus; Bathing water
• DOI: 10.1016/j.watres.2013.08.002
• ISSN: 0043-1354

We used site-specific quantitative microbial risk assessment (QMRA) to assess the probability of adenovirus illness for three groups of swimmers: adults with primary contact, children with primary contact, and secondary contact regardless of age. Human enteroviruses and adenoviruses were monitored by qPCR in a multi-use watershed and Adenovirus type 40/41 was detected in 11% of 73 samples, ranging from 147 to 4117 genomes per liter. Enterovirus was detected only once (32 genomes per liter). Seven of eight virus detections occurred when E. coli concentrations were below the single sample maximum water quality criterion for contact recreation, and five of eight virus detections occurred when fecal coliforms were below the corresponding criterion. We employed dose-harmonization to convert viral genome measurements to TCID50 values needed for dose–response curves. The three scenarios considered different amounts of water ingestion and Monte Carlo simulation was used to account for the variability associated with the doses. The mean illness risk in children based on adenovirus measurements obtained over 11 months was estimated to be 3.5%, which is below the 3.6% risk considered tolerable by the current United States EPA recreational criteria for gastrointestinal illnesses (GI). The mean risks of GI illness for adults and secondary contact were 1.9% and 1.0%, respectively. These risks changed appreciably when different distributions were fitted to the data as determined by Monte Carlo simulations. In general, risk was at a maximum for the log-logistic distribution and lowest for the hockey stick distribution in all three selected scenarios. Also, under default assumptions, the risk was lowered considerably when assuming that only a small proportion of Adenovirus 40/41 (3%) was as infectious as Adenovirus type 4, compared to the assumption that all genomes were Adenovirus 4. In conclusion, site-specific QMRA on water-borne adenoviruses in this watershed provided a similar level of protection against public health risks as would be obtained by enumeration of fecal indicator bacteria under the new U.S. EPA guidelines. Importance of site-specific risk assessment in recreational waters. • Children – recreational users; • Primary users – adult (standing in the water) in this scenario; • Primary contact – incidental ingestion of water; • Secondary user – child playing in the sand on beach. [Display omitted] •Illness risks modeled in adults and children with primary contact and secondary users regardless of age.•We model assuming that only a small proportion of detected Adenovirus 40/41 is as infectious as Adenovirus type 4.•Dose-harmonization for qPCR data reduces pathogen dose of enteric virus.•Significant changes in mean estimated risk from different distributions fitted to concentrations of water-borne pathogens.•First report of site-specific QMRA in freshwater in the United States.