title: Occurrence of norovirus in raw sewage - A systematic literature review and meta-analysis.
abstract: Human noroviruses (NoV) are a leading cause of recreational waterborne illnesses and responsible for the majority of viral-associated gastrointestinal illnesses nationwide. We conducted a systematic literature review of published peer-reviewed publications to identify NoV density data in wastewater influent, and provided an approach for developing pathogen density distributions, using the NoV data. Literature review inclusion criteria included scope, study quality, and data availability. A non-parametric bootstrap statistical model was used to estimate the NoV distribution in wastewater influent. The approach used accounts for heterogeneity in study-specific distribution curves, sampling locations, and sampling season and provides a comprehensive representation of the data. Study results illustrate that pooling all of the available NoV data together in a meta-analysis provides a more comprehensive understanding of the technical literature than what could be appreciated from individual studies. The studies included in this analysis indicate a high density of NoV in wastewater influent (overall mean = 4.6 log10genome copies (GC)/liter (L)), with a higher density of NoV genogroup (G) II (overall mean = 4.9 log10GC/L) than for GI (overall mean = 4.4 log10GC/L for GI). The bootstrapping approach was also used to account for differences in seasonal and geographical occurrences of NoV GI and GII. The methods presented are reproducible and can be used to develop QMRA-ready density distributions for other viral pathogens in wastewater influent, effluent, and ambient waters. To our knowledge, our results are the first to quantitatively characterize seasonal and geographic differences, which could be particularly useful for future risk assessments.
authors.affiliation: ICF, LLC, 9300 Lee Highway, Fairfax, VA, 22031, USA. Electronic address: Sorina.Eftim@icf.com.
authors.forename: Sorina E
authors.initials: SE
authors.lastname: Eftim
authors.affiliation: ICF, LLC, 9300 Lee Highway, Fairfax, VA, 22031, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Hong
authors.affiliation: Soller Environmental, LLC, 3022 King St, Berkeley, CA, 94703, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Soller
authors.affiliation: Stanford University, 450 Serra Mall, Stanford, CA, 94305, USA.
authors.forename: Alexandria
authors.initials: A
authors.lastname: Boehm
authors.affiliation: ICF, LLC, 9300 Lee Highway, Fairfax, VA, 22031, USA.
authors.forename: Isaac
authors.initials: I
authors.lastname: Warren
authors.affiliation: ICF, LLC, 9300 Lee Highway, Fairfax, VA, 22031, USA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Ichida
authors.affiliation: U.S. Environmental Protection Agency, Office of Water, Office of Science and Technology, 1200 Pennsylvania Avenue, NW, Washington, DC, 20460, USA.
authors.forename: Sharon P
authors.initials: SP
authors.lastname: Nappier
mesh_terms: D005838:Genotype; D006801:Humans; D029322:Norovirus / Q000235:genetics*; D012722:Sewage / Q000821:virology*; D062065:Wastewater / Q000821:virology; D018508:Water Purification
chemical_list: D012722:Sewage; D062065:Wastewater
keywords: Bootstrap; Microbial risk assessment; Norovirus; Systematic review; Wastewater; Waterborne pathogen density