From a health prospective, it is critical to provide a comprehensive model which integrates all the parameters involved in virus transmission and its consequences on human body. In order to estimate the health risks, for workers and residents, associated with an exposure airborne viruses emitted from a wastewater treatment (WWTP), the concentration levels of viruses in emitted bioaerosols over a twelve-month period were measured by real-time polymerase chain reaction (RT-PCR). A combined Gaussian plum dispersion model and quantitative microbial risk assessment (QMRA) with Monte-Carlo simulation served as suitable explanatory tools to estimate the risk of acquiring gastrointestinal illness (GI) due to exposure to air containing Rotavirus (RoV) and Norovirus (NoV) bioaerosols. Additionally, DALY metric was applied to quantify the disability and mortality for workers and residents. RoV and NoV were detected above aeration tank with annual mean concentration 27 and 3099 (Viruses/m³.h), respectively. The medium calculated DALY indicator based on viral loads in contaminant source (RoV:5.76 × 10⁻² and NoV:1.23 × 10⁻¹) and estimated in different distances away (300–1000 m) (RoV:2.87 × 10⁻²- 2.75 × 10⁻² and NoV:1.14 × 10⁻¹-1.13 × 10⁻¹) were markedly higher than the threshold values recommended by US EPA (10⁻⁴ DALY pppy) and WHO (10⁻⁶ DALY pppy). The sensitivity analysis highlighted dose exposure and disease burden per case (DBPC) as two most influential factors for both workers and residents following exposure to two pathogens of concern. Due to high resistance and high concentration in the environment, the presence of RoV and NoV can intensify the consequences of diarrhea especially for children under five years of age; A comprehensible and transparent presentation of DALYs and QMRA can help decision makers and responsibilities to justify the priorities of exposure to wastewater in comparison with other risks of daily life.

RT-qPCR allows sensitive detection of viral particles of both infectious and noninfectious viruses in water environments, but cannot discriminate non-infectious from infectious viruses. In this study, we aimed to optimize RT-qPCR-based detection of chlorine-inactivated human norovirus (NoV) and pepper mild mottle virus (PMMoV) in suspension by pretreatment with an optimal combination of a monoazide and a detergent that can efficiently penetrate damaged viral capsids. Four methods were compared to determine the efficacy of chlorine disinfection (at 1, 3, and 5 min mg/L): (A) RT-qPCR alone, (B) RT-qPCR assay preceded by magnetic bead separation for enrichment of viral particles (MBS-RT-qPCR), (C) MBS-RT-qPCR assay with pretreatment with propidium monoazide (PMA-MBS-RT-qPCR), and (D) PMA-MBS-RT-qPCR assay with pretreatment with sodium lauroyl sarcosinate (INCI-PMA-MBS-RT-qPCR). On the basis of a PMA optimization assay, 200 and 300 μM PMA were used in subsequent experiments for NoV GII.4 and PMMoV, respectively. Optimal INCI concentrations, having minimal influence on NoV GII.4 and PMMoV, were found to be 0.5% and 0.2% INCI, respectively. For NoV GII.4, there were significant differences (P < 0.05) in log₁₀ genome copies between the PMA-treated and the INCI + PMA-treated samples (log₁₀ genome copies differed by 1.11 and 0.59 log₁₀ for 3 and 5 min mg/L of chlorine, respectively). For PMMoV, INCI induced differences in log₁₀ genome copies of 0.92, 1.18, and 1.86, for 1, 3, and 5 min mg/L of chlorine, respectively. Overall, the results of this study indicate that an optimal combination of PMA and INCI could be very useful for evaluating disinfection methods in water treatment strategies.

The extensive use of reclaimed wastewater (RW) as a source of urban landscape pond replenishment, stimulated by the lack of surface water (SW) resources, has raised public concern. Greater attention should be paid to pond sediments, which act as ‘sinks’ and ‘sources’ of contaminants to the overlying pond water. Three ponds replenished with RW (RW ponds) in three Chinese cities were chosen to investigate 22 indices of sediment quality in four categories: eutrophication, heavy metal, ecotoxicity and pathogens risk. RW ponds were compared with other ponds of similar characteristics in the same cities that were replenished with SW (SW ponds). Our results show a strong impact of RW to the eutrophication and pathogenic risks, which are represented by organic matter, water content, total nitrogen, total phosphorus and phosphorus fractions, and pathogens. In particular, total phosphorus concentrations in the RW pond sediments were, on average, 50% higher than those of SW ponds. Moreover, the content of phosphorus, extracted by bicarbonate/dithionite (normally represented by BD-P) and NaOH (NaOH-P), were 2.0- and 2.83-times higher in RW ponds, respectively. For pathogens, the concentrations of norovirus and rotavirus in RW pond sediments were, on average, 0.52 and 0.30- log times those of SW ponds. The duration of RW replenishment was proved to have a marked impact on the eutrophication and pathogens risks from sediments. The continued use of RW for replenishment increases the eutrophication risk, and the pathogens risk, especially by viral pathogens, becomes greater.

To establish a relationship between viruses and chemicals, they were analysed in oyster Crassostrea gigas from an Italian experimental station. The chemicals concentrations were: Σ6 NDL-PCBs 0.82–7.12 ng g⁻¹; BaP LOQ (<0.2 μg kg⁻¹) to 1.2 μg kg⁻¹; PAH4 LOQ (<0.2 μg kg⁻¹) to 9.8 μg kg⁻¹; Cd 0.073–0.365 mg kg⁻¹; Pb 0.010–0.487 mg kg⁻¹; and Hg < LOQ (0.089 mg kg⁻¹). The viruses identified included: noroviruses (NoVGI/GII), astrovirus (AsV), rotavirus (RV), adenovirus (AdV), and sapovirus (SaV), while hepatitis A, hepatitis E, and Aichi viruses were not detected. Significant correlations were observed for NDL-PCBs with NoVGI, NoVGII, and AdV; BaP and PAH4 with NoVGI and AsV; Cd with RV; Pb with NoVGI and AsV; PAHs with Pb; AsV with NoVGI; and AdV with NoVGII. The study indicated as C. gigas is a model for correlating pollutants and foodborne viruses, whose co-presence may represent an additional food safety risk.

Noroviruses are the most common cause of gastroenteritis outbreaks in humans and bivalve shellfish consumption is a recognized route of infection. Our aim was to detect and characterize norovirus in bivalves from a coastal city of Brazil. Nucleic acid was extracted from the bivalve's digestive tissue concentrates using magnetic beads. From March 2018 to June 2019, 77 samples were screened using quantitative RT-PCR. Noroviruses were detected in 41.5%, with the GII being the most prevalent (37.7%). The highest viral load was 3.5 × 106 and 2.5 × 105 GC/g in oysters and mussels, respectively. PMA-treatment demonstrated that a large fraction of the detected norovirus corresponded to non-infectious particles. Genetic characterization showed the circulation of the GII.2[P16] and GII.4[P4] genotypes. Norovirus detection in bivalves reflects the anthropogenic impact on marine environment and serves as an early warning for the food-borne disease outbreaks resulting from the consumption of contaminated molluscs.

Profiling bathing waters supported by Quantitative Microbial Risk Assessment (QMRA) is key to the WHO's recommendations for the 2020/2021 revision of the European Bathing Water Directive. We developed an area-specific QMRA model on four pathogens, using fecal indicator concentrations (E. coli, enterococci) for calculating pathogen loads. The predominance of illness was found to be attributable to Human Adenovirus, followed by Salmonella, Vibrio, and Norovirus. Overall, the cumulative illness risk showed a median of around 1 case/10000 exposures. The risk estimates were strongly influenced by the indicators that were used, suggesting the need for a more detailed investigation of the different sources of fecal contamination. Area-specific threshold values for fecal indicators were estimated on a risk-basis by modelling the cumulative risk against E. coli and enterococci concentrations. To improve bathing waters assessment, we suggest considering source apportionment, locally estimating of pathogen/indicator ratios, and calculating site-specific indicators thresholds based on risk assessment.

Bivalve shellfish may accumulate contaminants of public health concern including pathogenic bacteria and viruses. Microbiological monitoring of production areas is based on faecal coliforms in water in the USA and Escherichia coli in bivalve molluscs in the European Union. E. coli is known to reflect contamination with Salmonella enterica but not necessarily with other human pathogens such as enteric viruses. A structured field study was undertaken at three locations in order to investigate the geographical and temporal variability of E. coli and norovirus (NoV). Total norovirus concentration differed significantly by both sampling site and sampling date. A significant correlation was found between total NoV concentration and E. coli concentration by sample, but not with E. coli in seawater. The results have implications for the establishment of sampling plans for NoV in harvesting areas and potentially also for the approach taken to classification based on faecal indicator bacteria.

The effects of precipitation on the hygienic quality of water and blue mussels collected from five different localities in the urban areas in the Inner Oslofjord were investigated, with samples analysed for Escherichia coli, Salmonella spp., pathogenic Vibrio spp., Norovirus, Sapovirus, Cryptosporidium spp. and Giardia duodenalis. The sampling sites were located at varying distances from the outlet of combined sewer overflows (CSO)-impacted rivers/streams. In general, 1–3 log10 increases in fecal indicator bacteria and human pathogens were observed after heavy rainfalls. Blue mussels appeared to be a useful indicator of the impact of sewage at these sites, and generally a good correlation was identified between concentrations of E. coli and other human pathogens in the mussels. Provision of general advice to the public of avoiding areas near the outlets of CSO-impacted rivers after heavy rainfall may reduce the risk of gastroenteritis by bathers and others that may swallow water during recreational activities.

The presence of Norovirus (NoV) and Hepatitis E virus (HEV) in non-depurated and depurated oysters raised in the north-west Italian coast was investigated by quantitative real-time RT-PCR. Total and inorganic arsenic (As) and the presence of marine biotoxins (DSP, ASP, PSP) by LC-MS were also investigated. NoV was detected through all the sampling period in non depurated and depurated oysters with highest levels during wintertime (>10⁴ genome copies per gram, gc/g) and minimum values in summer below the LOQ (<130/140 gc/g). HEV has never been found as well as biotoxins. Total As concentration was found in oysters in the range 0.45–3.0 mg/kg, while inorganic As was found in all samples in concentrations below the LOQ (<0.020 mg/kg). The study highlights how the 24 h depuration process didn't reduce significantly NoV levels and therefore the high concentration of NoV in oysters could represent a risk for consumers especially during winter and spring months.

Norovirus is detected from shellfish and environmental water more frequently in winter than in other seasons. However, there is no report regarding its viability in actual seawater in situ. We investigated the viability of murine norovirus strain 1 (MNV-1), a surrogate for human norovirus, in 2 types of aquatic locations, a seawater pool carrying oceanic water and inner bay carrying brackish water. Sterilized seawater was inoculated with MNV-1 and enclosed in dialysis tubes, which were placed at the 2 locations. MNV-1 exhibited higher level of viability in brackish than in oceanic water. Factors that influenced the viability of MNV-1 included salt concentration as well as temperature of the seawater. Therefore, based on our findings, coastal brackish water that is routinely used for harvesting or cleaning seafood at fishing ports may promote the viability of norovirus.