Environmental Surveillance of Norovirus Genogroups I and II for Sensitive Detection of Epidemic Variants

Abstract

Sewage samples have been investigated to study the norovirus concentrations in sewage or the genotypes of noroviruses circulating in human populations. However, the statistical relationship between the concentration of the virus and the number of infected individuals and the clinical importance of genotypes or strains detected in sewage are unclear. In this study, we carried out both environmental and clinical surveillance of noroviruses for 3 years, 2013 to 2016. We performed cross-correlation analysis of the concentrations of norovirus GI or GII in sewage samples collected weekly and the reported number of gastroenteritis cases. Norovirus genotypes in sewage were also analyzed by pyrosequencing and compared with those identified in stool samples. The cross-correlation analysis found the peak coefficient ( = 0.51) at a lag of zero, indicating that the variation in the GII concentration, expressed as the log number of copies per milliliter, was coincident with that in the gastroenteritis cases. A total of 15 norovirus genotypes and up to 8 genotypes per sample were detected in sewage, which included all of the 13 genotypes identified in the stool samples except 2. GII.4 was most frequently detected in both sample types, followed by GII.17. Phylogenetic analysis revealed that a strain belonging to the GII.17 Kawasaki 2014 lineage had been introduced into the study area in the 2012-2013 season. An increase in GI.3 cases was observed in the 2015-2016 season, and sewage monitoring identified the presence of GI.3 in the previous season (2014-2015). Our results demonstrated that monitoring of noroviruses in sewage is useful for sensitive detection of epidemic variants in human populations. We obtained statistical evidence of the relationship between the variation in the norovirus GII concentration in sewage and that of gastroenteritis cases during the 3-year study period. Sewage sample analysis by a pyrosequencing approach enabled us to understand the temporal variation in the norovirus genotypes circulating in human populations. We found that a strain closely related to the GII.17 Kawasaki 2014 lineage had been introduced into the study area at least 1 year before its appearance and identification in clinical cases. A similar pattern was observed for GI.3; cases were reported in the 2015-2016 season, and closely related strains were found in sewage in the previous season. Our observation indicates that monitoring of noroviruses in sewage is useful for the rapid detection of an epidemic and is also sensitive enough to study the molecular epidemiology of noroviruses. Applying this approach to other enteric pathogens in sewage will enhance our understanding of their ecology.

Temporal variations in genotype distribution of human sapoviruses and Aichi virus 1 in wastewater in Southern Arizona, United States

“…However, there have been only limited studies reporting genotype distribution of these viruses in water samples (Kitajima et al 2010a(Kitajima et al , 2011aSano et al 2011;Haramoto and Kitajima 2017). We conceived the present study because usefulness of virus monitoring in wastewater for understanding viral epidemiology has been demonstrated for other waterborne pathogenic viruses, such as noroviruses and hepatitis A virus (Hellm er et al 2014;Kazama et al 2017).…”

Fecal Source Tracking in A Wastewater Treatment and Reclamation System Using Multiple Waterborne Gastroenteritis Viruses

“…The general trend is that the dominance of environmental strains differ from strains in the host. Due to the inherent difficulty in finding a correlation between environmental contamination and cases of infection, microbiological monitoring of the environment might be more helpful for source tracking and water safety control rather than risk assessment [47,48]. In addition, limited waterborne viral outbreaks usually occurred at distance from the original source of contamination.…”

Virus Type-Specific Removal in a Full-Scale Membrane Bioreactor Treatment Process

“…Only samples with MgV recovery efficiencies above 1% were considered for quantification (Miura et al, 2016). We used the MgV recovery efficiency as a quality assurance parameter only and did not use to adjust test results (Kazama et al, 2017).…”