Evaluation of Norovirus Reduction in Environmentally Contaminated Pacific Oysters During Laboratory Controlled and Commercial Depuration.

Norovirus contamination of oysters is the lead cause of non-bacterial gastroenteritis and a significant food safety concern for the oyster industry. Here, norovirus reduction from Pacific oysters (Crassostrea gigas), contaminated in the marine environment, was studied in laboratory depuration trials and in two commercial settings. Norovirus concentrations were measured in oyster digestive tissue before, during and post-depuration using the ISO 15216-1 quantitative real-time RT-PCR method. Results of the laboratory-based studies demonstrate that statistically significant reductions of up to 74% of the initial norovirus GII concentration was achieved after 3 days at 17-21 °C and after 4 days at 11-15 °C, compared to 44% reduction at 7-9 °C. In many trials norovirus GII concentrations were reduced to levels below 100 genome copies per gram (gcg-1; limit of quantitation; LOQ). Virus reduction was also assessed in commercial depuration systems, routinely used by two Irish oyster producers. Up to 68% reduction was recorded for norovirus GI and up to 90% for norovirus GII reducing the geometric mean virus concentration close to or below the LOQ. In both commercial settings there was a significant difference between the levels of reduction of norovirus GI compared to GII (p < 0.05). Additionally, the ability to reduce the norovirus concentration in oysters to < LOQ differed when contaminated with concentrations below and above 1000 gcg-1. These results indicate that depuration, carried out at elevated (> 11 °C) water temperatures for at least 3 days, can reduce the concentration of norovirus in oysters and therefore consumer exposure providing a practical risk management tool for the shellfish industry.

Gastroenteric Viruses Detection in a Drinking Water Distribution-to-Consumption System in a Low-Income Community in Rio de Janeiro.

The availability of drinking water is one of the main determinants of quality of life, disease prevention and the promotion of health. Viruses are important agents of waterborne diseases and have been described as important markers of human faecal contamination. This study aimed to investigate viruses' presence as an indicator of drinking water quality in low-income communities in the Manguinhos area, Rio de Janeiro, Brazil. Three hundred and four drinking water samples (2L/each) were collected along the drinking water distribution-to-consumption pathway in households, as well as healthcare and school units. Water samples were collected both directly from the water supply prior to distribution and after storage in tanks and filtration units. Using qPCR, viruses were detected 50 times in 45 water samples (15%), 19 of these being human adenovirus, 17 rotavirus A and 14 norovirus GII. Viral loads recovered ranged from 5E+10 to 8.7E+106 genome copies/Liter. Co-detection was observed in five household water samples and there was no difference regarding virus detection across sampling sites. Precarious and inadequate environmental conditions characterized by the lack of local infrastructure regarding basic sanitation and waste collection in the territory, as well as negligent hygiene habits, could explain viral detection in drinking water in regions with a water supply system.

Comparing Mouse Health Monitoring Between Soiled-bedding Sentinel and Exhaust Air Dust Surveillance Programs.

To monitor rodent colony health in research facilities, soiled-bedding sentinel (SBS) animals have traditionally been used. SBS can be tested by various methods, which may include serology, PCR analysis, and necropsy. Several pathogens are unreliably detected by using SBS or transmitted poorly through soiled bedding, and collection and evaluation of SBS samples can be time-intensive. Recently, exhaust air dust (EAD) testing through PCR analysis has emerged as an adjunct or replacement method for rodent colony health monitoring. EAD monitoring may provide a more efficient, sensitive, and humane method for monitoring health status. Using both EAD and SBS health monitoring, we evaluated colony health over the course of 1 y in 3 research barrier rooms in which mice were housed exclusively on IVC racks. Three pathogens-Helicobacter spp., Rodentibacter spp. (previously Pasteurella pneumotropica), and murine norovirus (MNV)-were not excluded in 2 of the rooms, and we expected that these mice would test positive with some regularity. EAD monitoring was significantly more sensitive than SBS for detection of the bacterial agents. SBS failed to detect Helicobacter spp. at time points when EAD had 100% detection in the rooms that did not exclude the bacteria. The detection of MNV did not differ between health monitoring systems at any time point. The findings suggest that EAD is especially valuable in detecting bacteria poorly transmitted through soiled bedding. In addition, the corresponding results with MNV detection suggest that EAD surveillance can reliably be implemented as an alternative to SBS monitoring in a facility in which mice are housed exclusively on IVC racks.

Estimate of the annual burden of foodborne illness in nondeployed active duty US Army Service Members: five major pathogens, 2010-2015.

In this study, we estimate the burden of foodborne illness (FBI) caused by five major pathogens among nondeployed US Army service members. The US Army is a unique population that is globally distributed, has its own food procurement system and a food protection system dedicated to the prevention of both unintentional and intentional contamination of food. To our knowledge, the burden of FBI caused by specific pathogens among the US Army population has not been determined. We used data from a 2015 US Army population survey, a 2015 US Army laboratory survey and data from FoodNet to create inputs for two model structures. Model type 1 scaled up case counts of Campylobacter jejuni, Shigella spp., Salmonella enterica non-typhoidal and STEC non-O157 ascertained from the Disease Reporting System internet database from 2010 to 2015. Model type 2 scaled down cases of self-reported acute gastrointestinal illness (AGI) to estimate the annual burden of Norovirus illness. We estimate that these five pathogens caused 45 600 (5%-95% range, 30 300-64 000) annual illnesses among nondeployed active duty US Army Service members. Of these pathogens, Norovirus, Campylobacter jejuni and Salmonella enterica non-typhoidal were responsible for the most illness. There is a tremendous burden of AGI and FBI caused by five major pathogens among US Army Soldiers, which can have a tremendous impact on readiness of the force. The US Army has a robust food protection program in place, but without a specific active FBI surveillance system across the Department of Defence, we will never have the ability to measure the effectiveness of modern, targeted, interventions aimed at the reduction of specific foodborne pathogens.

Norovirus Gastroenteritis among Hospitalized Patients, Germany, 2007-2012.

We estimated numbers of hospitalizations for norovirus gastroenteritis (NGE) and associated medical costs in Germany, where norovirus testing is high because reimbursement is affected. We extracted aggregate data for patients hospitalized with a primary or secondary code from the International Classification of Diseases, 10th Revision (ICD-10), NGE diagnosis during 2007-2012 from the German Federal Statistics Office. We assessed reliability of the coding system in patient records from a large academic hospital. Approximately 53,000-90,000 NGE hospitalizations occurred annually in Germany (21,000-33,000 with primary and 32,000-57,000 with secondary ICD-10-coded NGE diagnoses). Rates of hospitalization with NGE as primary diagnosis were highest in children <2 years of age; rates of hospitalization with NGE as secondary diagnosis were highest in adults >85 years of age. The average annual reimbursed direct medical cost of NGE hospitalizations was €31-43 million. Among patients with a NGE ICD-10 code, 87.6% had positive norovirus laboratory results.

Assessment of viral and bacterial contamination of fresh and ripened semi-hard cheeses.

This study aimed to evaluate viral and bacterial contamination from typical Brazilian cheeses, such as Minas (fresh) and Prato (ripened), commercially obtained in the Greater Metropolitan Region of the State of Rio de Janeiro, Brazil. Minas [30], Prato [30] and sliced Prato [30] cheese samples were investigated for norovirus genogroup I and II (NoV GI-II) and human adenovirus (HAdV) by direct nucleic acid extraction using TRIzol and amplification by TaqMan based quantitative polymerase chain reaction. Listeria monocytogenes, Salmonella spp., coagulase-positive staphylococci (CPS) and fecal coliforms were also assessed by using standard counting methods. NoV GI and GII were detected in one sample (1.1%) each and HAdV in nine samples (10.0%) while bacteriological analysis revealed five samples (5.5%) contaminated with L. monocytogenes, 27 (30.0%) with fecal coliforms and 10 (11.1%) with CPS. Salmonella spp. was not detected in any sample. Viruses were detected in 11 samples (12.2%), of which 9 met the microbiological criteria used to evaluate the microbiological quality of the cheeses, stressing the importance of considering virological parameters for monitoring this food matrix.

Single-step detection of norovirus tuning localized surface plasmon resonance-induced optical signal between gold nanoparticles and quantum dots.

A new method of label free sensing approach with superior selectivity and sensitivity towards virlabel-freeon is presented here, employing the localized surface plasmon resonance (LSPR) behavior of gold nanoparticles (AuNPs) and fluorescent CdSeTeS quantum dots (QDs). Inorganic quaternary alloyed CdSeTeS QDs were capped with L-cysteine via a ligand exchange reaction. Alternatively, citrate stabilized AuNPs were functionalized with 11-mercaptoundecanoic acid to generate carboxylic group on the gold surface. The carboxylic group on the AuNPs was subjected to bind covalently with the amine group of L-cysteine capped CdSeTeS QDs to form CdSeTeS QDs/AuNPs nanocomposites. The fluorescence of CdSeTeS QDs/AuNPs nanocomposite shows quenched spectrum of CdSeTeS QDs at 640 nm due to the close interaction with AuNPs. However, after successive addition of norovirus-like particles (NoV-LPs), steric hindrance-induced LSPR signal from the adjacent AuNPs triggered the fluorescence enhancement of QDs in proportion to the concentration of the target NoV-LPs. A linear range of 10-14 to 10-9 g mL-1 NoV-LPs with a detection limit of 12.1 × 10-15 g mL-1 was obtained. This method was further applied on clinically isolated norovirus detection, in the range of 102-105 copies mL-1 with a detection limit of 95.0 copies mL-1, which is 100-fold higher than commercial ELISA kit. The superiority of the proposed sensor over other conventional sensors is found in its ultrasensitive detectability at low virus concentration even in clinically isolated samples. This proposed detection method can pave an avenue for the development of high performance and robust sensing probes for detection of virus in biomedical applications.

Urban sanitation coverage and environmental fecal contamination: Links between the household and public environments of Accra, Ghana.

Exposure to fecal contamination in public areas, especially in dense, urban environments, may significantly contribute to enteric infection risk. This study examined associations between sanitation and fecal contamination in public environments in four low-income neighborhoods in Accra, Ghana. Soil (n = 72) and open drain (n = 90) samples were tested for E. coli, adenovirus, and norovirus. Sanitation facilities in surveyed households (n = 793) were categorized by onsite fecal sludge containment ("contained" vs. "uncontained") using previous Joint Monitoring Program infrastructure guidelines. Most sanitation facilities were shared by multiple households. Associations between spatial clustering of household sanitation coverage and fecal contamination were examined, controlling for neighborhood and population density (measured as enumeration areas in the 2010 census and spatially matched to sample locations). E. coli concentrations in drains within 50m of clusters of contained household sanitation were more than 3 log-units lower than those outside of clusters. Further, although results were not always statistically significant, E. coli concentrations in drains showed consistent trends with household sanitation coverage clusters: concentrations were lower in or near clusters of high coverage of household sanitation facilities-especially contained facilities-and vice versa. Virus detection in drains and E. coli concentrations in soil were not significantly associated with clustering of any type of household sanitation and did not exhibit consistent trends. Population density alone was not significantly associated with any of the fecal contamination outcomes by itself and was a significant, yet inconsistent, effect modifier of the association between sanitation clusters and E. coli concentrations. These findings suggest clustering of contained household sanitation, even when shared, may be associated with lower levels of fecal contamination within drains in the immediate public domain. Further research is needed to better quantify these relationships and examine impacts on health.

Quantitative microbial risk assessment to estimate the risk of diarrheal diseases from fresh produce consumption in India.

This study estimates illness (diarrhea) risks from fecal pathogens that can be transmitted via fecal-contaminated fresh produce. To do this, a quantitative microbial risk assessment (QMRA) framework was developed in National Capital Region, India based on bacterial indicator and pathogen data from fresh produce wash samples collected at local markets. Produce wash samples were analyzed for fecal indicator bacteria (Escherichia coli, total Bacteroidales) and pathogens (Salmonella, Shiga-toxin producing E. coli (STEC), enterohemorrhagic E. coli (EHEC)). Based on the E. coli data and on literature values for Cryptosporidium and norovirus, the annual mean diarrhea risk posed by ingestion of fresh produce ranged from 18% in cucumbers to 59% in cilantro for E. coli O157:H7, and was <0.0001% for Cryptosporidium; for norovirus the risk was 11% for cucumbers and up to 46% for cilantro. The risks were drastically reduced, from 59% to 4% for E. coli O157:H7, and from 46% to 2% for norovirus for cilantro in post-harvest washing and disinfection scenario. The present QMRA study revealed the potential hazards of eating raw produce and how post-harvest practices can reduce the risk of illness. The results may lead to better food safety surveillance systems and use of hygienic practices pre- and post-harvest.

Burden of Severe Norovirus Disease in Taiwan, 2003-2013.

Background: Despite the increasingly recognized role of norovirus in global acute gastroenteritis (AGE), specific estimates of the associated disease burden remain sparse, primarily due to limited availability of sensitive norovirus diagnostics in the clinical setting. We sought to estimate the incidence of norovirus-associated hospitalizations by age group in Taiwan using a previously developed indirect regression method. Methods: AGE-related hospitalizations in Taiwan were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes abstracted from a national database; population data were provided from the Department of Household Registration Affairs. Population and hospitalizations were aggregated by month and year (July 2003-June 2013) and grouped by age: <5 years, 5-19 years, 20-64 years, and ≥65 years. Monthly counts of cause-unspecified AGE hospitalizations were modeled as a function of counts of known causes, and the residuals were then analyzed to estimate norovirus-associated hospitalizations. Results: Over the study period, an annual mean of 101400 gastroenteritis-associated hospitalizations occurred in Taiwan (44 per 10000 person-years), most of which (83%) had no specified cause. The overall estimated rate of norovirus-associated hospitalizations was 6.7 per 10000 person-years, with the highest rates in children aged <5 years (63.7/10000 person-years). Predicted norovirus peaked in 2006-2007 and 2012-2013. Conclusions: Our study is one of the first to generate a population-based estimate of severe norovirus disease incidence in Asia, and highlights the large burden of norovirus in Taiwan, particularly in children. Predicted peak norovirus seasons coincided with the emergence of new strains and resulting pandemics, supporting the validity of the estimates.

Estimating the Hospital Burden of Norovirus-Associated Gastroenteritis in England and Its Opportunity Costs for Nonadmitted Patients.

Background: Norovirus places a substantial burden on healthcare systems, arising from infected patients, disease outbreaks, beds kept unoccupied for infection control, and staff absences due to infection. In settings with high rates of bed occupancy, opportunity costs arise from patients who cannot be admitted due to beds being unavailable. With several treatments and vaccines against norovirus in development, quantifying the expected economic burden is timely. Methods: The number of inpatients with norovirus-associated gastroenteritis in England was modeled using infectious and noninfectious gastrointestinal Hospital Episode Statistics codes and laboratory reports of gastrointestinal pathogens collected at Public Health England. The excess length of stay from norovirus was estimated with a multistate model and local outbreak data. Unoccupied bed-days and staff absences were estimated from national outbreak surveillance. The burden was valued conventionally using accounting expenditures and wages, which we contrasted to the opportunity costs from forgone patients using a novel methodology. Results: Between July 2013 and June 2016, 17.7% (95% confidence interval [CI], 15.6%‒21.6%) of primary and 23.8% (95% CI, 20.6%‒29.9%) of secondary gastrointestinal diagnoses were norovirus attributable. Annually, the estimated median 290000 (interquartile range, 282000‒297000) occupied and unoccupied bed-days used for norovirus displaced 57800 patients. Conventional costs for the National Health Service reached £107.6 million; the economic burden approximated to £297.7 million and a loss of 6300 quality-adjusted life-years annually. Conclusions: In England, norovirus is now the second-largest contributor of the gastrointestinal hospital burden. With the projected impact being greater than previously estimated, improved capture of relevant opportunity costs seems imperative for diseases such as norovirus.

Incidence and Clinical Profile of Norovirus Disease in Guatemala, 2008-2013.

Background: Acute gastroenteritis (AGE) is a leading infectious cause of morbidity worldwide, particularly among children in developing countries. With the decline of rotavirus disease rates following introduction of rotavirus vaccines, the relative importance of norovirus will likely increase. Our objectives in this study were to determine the incidence and clinical profile of norovirus disease in Guatemala. Methods: We analyzed data from a population-based surveillance study conducted in Guatemala from 2008 through 2013. Demographic information, clinical data, and stool samples were collected from patients who presented with AGE (≥3 liquid stools within 24 hours that initiated 7 days before presentation). Estimated incidence of hospitalized, outpatient, and total community norovirus disease was calculated using surveillance data and household surveys of healthcare use. Results: We included 999 AGE hospitalizations and 3189 AGE outpatient visits at facilities, of which 164 (16%) and 370 (12%), respectively, were positive for norovirus. Severity of norovirus was milder than of rotavirus. Community incidence of norovirus ranged from 2068 to 4954 per 100000 person-years (py) in children aged<5 years. Children aged <5 years also had higher incidence of norovirus-associated hospitalization (51-105 per 100000 py) compared with patients aged ≥5 years (0-1.6 per 100000 py and 49-80 per 100000 py, respectively). Conclusions: This study highlights the burden of norovirus disease in Guatemala, especially among young children. These data can help prioritize development of control strategies, including the potential use of vaccines, and provide a baseline to evaluate the impact of such interventions.

Evaluation of the suitability of a plant virus, pepper mild mottle virus, as a surrogate of human enteric viruses for assessment of the efficacy of coagulation-rapid sand filtration to remove those viruses.

Here, we evaluated the removal of three representative human enteric viruses - adenovirus (AdV) type 40, coxsackievirus (CV) B5, and hepatitis A virus (HAV) IB - and one surrogate of human caliciviruses - murine norovirus (MNV) type 1 - by coagulation-rapid sand filtration, using water samples from eight water sources for drinking water treatment plants in Japan. The removal ratios of a plant virus (pepper mild mottle virus; PMMoV) and two bacteriophages (MS2 and φX174) were compared with the removal ratios of human enteric viruses to assess the suitability of PMMoV, MS2, and φX174 as surrogates for human enteric viruses. The removal ratios of AdV, CV, HAV, and MNV, evaluated via the real-time polymerase chain reaction (PCR) method, were 0.8-2.5-log10 when commercially available polyaluminum chloride (PACl, basicity 1.5) and virgin silica sand were used as the coagulant and filter medium, respectively. The type of coagulant affected the virus removal efficiency, but the age of silica sand used in the rapid sand filtration did not. Coagulation-rapid sand filtration with non-sulfated, high-basicity PACls (basicity 2.1 or 2.5) removed viruses more efficiently than the other aluminum-based coagulants. The removal ratios of MS2 were sometimes higher than those of the three human enteric viruses and MNV, whereas the removal ratios of φX174 tended to be smaller than those of the three human enteric viruses and MNV. In contrast, the removal ratios of PMMoV were similar to and strongly correlated with those of the three human enteric viruses and MNV. Thus, PMMoV appears to be a suitable surrogate for human enteric viruses for the assessment of the efficacy of coagulation-rapid sand filtration to remove viruses.

Quantitative microbial risk assessment to estimate the health risk from exposure to noroviruses in polluted surface water in South Africa.

This study assessed the risks posed by noroviruses (NoVs) in surface water used for drinking, domestic, and recreational purposes in South Africa (SA), using a quantitative microbial risk assessment (QMRA) methodology that took a probabilistic approach coupling an exposure assessment with four dose-response models to account for uncertainty. Water samples from three rivers were found to be contaminated with NoV GI (80-1,900 gc/L) and GII (420-9,760 gc/L) leading to risk estimates that were lower for GI than GII. The volume of water consumed and the probabilities of infection were lower for domestic (2.91 × 10-8 to 5.19 × 10-1) than drinking water exposures (1.04 × 10-5 to 7.24 × 10-1). The annual probabilities of illness varied depending on the type of recreational water exposure with boating (3.91 × 10-6 to 5.43 × 10-1) and swimming (6.20 × 10-6 to 6.42 × 10-1) being slightly greater than playing next to/in the river (5.30 × 10-7 to 5.48 × 10-1). The QMRA was sensitive to the choice of dose-response model. The risk of NoV infection or illness from contaminated surface water is extremely high in SA, especially for lower socioeconomic individuals, but is similar to reported risks from limited international studies.

Methods for ascertaining norovirus disease burdens.

Norovirus is the commonest cause of gastrointestinal disease worldwide in. Infections with norovirus occur in all age groups, however, the highest incidence is in children aged less than five years. Surveillance of norovirus is complicated because most people do not contact medical services when they are ill. Nevertheless, Public health laboratory surveillance worldwide has demonstrated the dominance of GII.4 viruses in the population. Better epidemiological surveillance and outbreak investigations, coupled with wider implementation of molecular-based laboratory diagnostics are leading to better estimates of the burden of norovirus infections as well as improved outbreak control. Recent advances in cell culture systems for norovirus and current research investigating the distribution of norovirus-associated disease in the population, for whom the disease burden is greatest, understanding host susceptibility factors, and methodologies for ascertaining cases, are important in increasing our understanding of norovirus. The key to surveillance of norovirus is allying the epidemiology with surveillance of virology. With recent advances in laboratory culture systems for norovirus, next generation sequencing technologies, improved diagnostics and measuring phenotypic characteristics of noroviruses, there are new opportunities to advance understanding of this common and important human pathogen that will help design strategies for vaccine and antiviral development, and how these might be best deployed to control norovirus infection.

Nanofluidic digital PCR for the quantification of Norovirus for water quality assessment.

Sensitive detection of water- and foodborne enteric viruses is extremely relevant, especially due to the low concentrations in which they are found. Accurate and sensitive detection of Norovirus, the primary responsible for water- and foodborne outbreaks, is of particular importance. Quantification of Norovirus is commonly performed by quantitative RT-PCR (RT-qPCR). In recent years a new platform was developed, digital PCR, that quantifies without the need for a standard curve thus decreasing the errors associated with its utilization. The platform developed by LifeTechnologies, QuantStudio 3D Digital PCR is amongst the least studied digital platform and although it allows the direct detection of DNA targets it requires a two-step RT-PCR for the detection of RNA targets. In this work we developed a new protocol able to detect Norovirus using a one-step digital PCR reaction (RT-dPCR). The performance of the newly developed one-step digital PCR was compared to RT-qPCR for the detection of Norovirus genogroup I and genogroup II. The sensitivity of RT-dPCR was identical to that of RT-qPCR, and the quantitative data determined by both methods were not significantly different for most samples. This one-step absolute quantification approach is a useful tool to minimize the time spent currently using this particular platform to amplify viral RNA and to standardize quantification of enteric viruses in food and environmental samples. This study proved the usefulness of the newly developed RT-dPCR protocol for a sensitive and accurate detection of low-copy targets.

Probabilistic quantitative microbial risk assessment model of norovirus from wastewater irrigated vegetables in Ghana using genome copies and fecal indicator ratio conversion for estimating exposure dose.

The need to replace the commonly applied fecal indicator conversions ratio (an assumption of 1:10-5 virus to fecal indicator organism) in Quantitative Microbial Risk Assessment (QMRA) with models based on quantitative data on the virus of interest has gained prominence due to the different physical and environmental factors that might influence the reliability of using indicator organisms in microbial risk assessment. The challenges facing analytical studies on virus enumeration (genome copies or particles) have contributed to the already existing lack of data in QMRA modelling. This study attempts to fit a QMRA model to genome copies of norovirus data. The model estimates the risk of norovirus infection from the intake of vegetables irrigated with wastewater from different sources. The results were compared to the results of a corresponding model using the fecal indicator conversion ratio to estimate the norovirus count. In all scenarios of using different water sources, the application of the fecal indicator conversion ratio underestimated the norovirus disease burden, measured by the Disability Adjusted Life Years (DALYs), when compared to results using the genome copies norovirus data. In some cases the difference was >2 orders of magnitude. All scenarios using genome copies met the 10-4 DALY per person per year for consumption of vegetables irrigated with wastewater, although these results are considered to be highly conservative risk estimates. The fecal indicator conversion ratio model of stream-water and drain-water sources of wastewater achieved the 10-6 DALY per person per year threshold, which tends to indicate an underestimation of health risk when compared to using genome copies for estimating the dose.

Burden of acute gastroenteritis caused by norovirus in China: A systematic review.

BACKGROUND: To understand the epidemiology and disease burden of norovirus (NoVs) gastroenteritis in China, a systematic review was conducted. METHODS: Studies on acute gastroenteritis (AGE) caused by NoVs from mainland China, published before 2017 were searched. All retrieved articles were screened and reviewed by a standardized algorithm. NoVs detection rates as well as strain variations by ages, seasonal variations and geographic locations were analyzed using random-effects model. RESULTS: A total of 225 articles were included in the final analysis. Similar detection rates at 21.0% and 19.8% were obtained from the North and the South, respectively. NoVs infection occurred year round, with a peak between October and January in the North and between August and November in the South. High detection rates (∼29%) of NoVs were found in adults and the elderly and in children aged 6-35 months (∼22%). The predominant strains were GII.4 (70.4%), followed by GII.3 (13.5%). CONCLUSION: NoVs cause significant disease burden in China which warrants development of vaccines against NoVs, particularly for children and the elderly who are vulnerable to gastroenteritis diseases. To achieve a broad protection, continual monitoring NoV epidemics and strain variations for selection of proper vaccine strains is critical.

Assessment and risk modeling of airborne enteric viruses emitted from wastewater reused for irrigation.

Reclamation of wastewater (WW) for irrigation, after treatment represents a challenge that could alleviate pressure on water resources and address the increasing demand for agriculture. However, the risks to human health must be assessed, particularly those related to human enteric viruses that resist standard treatments in most wastewater treatment plants (WWTP). The risks associated with exposure to viral bioaerosols near WWTP and near agricultural plots irrigated with WW are poorly documented. The objectives of this study were to 1) better characterize human enteric viruses found in bioaerosols near a "standard WWTP" and over fields irrigated with treated WW and 2) propose a numeric model to assess the health risk to populations located close to the irrigated areas, with particular attention to norovirus, which is responsible for most viral gastroenteritis in France. Water and air samples were collected at various locations in the largest French WW-irrigated site near Clermont-Ferrand, at the WWTP entrance and after treatment, in the air above activated sludge basins, and above fields irrigated with WW. Various enteric viruses were found in the water samples collected both before and after treatment. Norovirus was the most abundant with >10e4 genome copies/l (GC/L) before treatment and ~10e3 GC/L after treatment. Low quantities (<10e3GC/m3) were detected in the air above active sludge pools and irrigated plots. Hepatitis E virus was detected in all sampled compartments. A quantitative microbial risk assessment (QMRA) approach, including a simplified atmospheric dispersion model, allowed assessment of norovirus infection risk. The Bayesian QMRA approach considered wind speed measurements over 21years, and the variability and uncertainty of all measurements throughout the chain up to the risk. The probability of infection within one year for the most exposed WWTP employees was >10e-4 for strong wind speed (≥3m/s) and a constant emission rate of 8e3 GC/m3/s. This probability decreases by 3 log when the distance to the emission source is doubled. This information can aid development of safe water reuse policies in terms of local setback distance and wind conditions for wastewater reuse.

Optimal strategies for the diagnosis of community-onset diarrhea in solid organ transplant recipients: Less is more.

BACKGROUND: Diarrhea, a common complication after solid organ transplant (SOT), is associated with allograft failure and death. No evidence-based guidelines exist for the evaluation of diarrhea in SOT recipients. We performed a cost analysis to derive a testing algorithm for the diagnosis of community-onset diarrhea that minimizes costs without compromising diagnostic yields. DESIGN: A cost analysis was performed on a retrospective cohort of 422 SOT admissions for community-onset diarrhea over an 18-month period. A stepwise testing model was applied on a population level to assess test costs relative to diagnostic yields. RESULTS: Over an 18-month period, 1564 diagnostic tests were performed and 127 (8.1%) returned positive. Diagnostic testing accounted for $95 625 of hospital costs. The tests with the lowest cost per decrease in the false-omission rate (FOR) were stool Clostridium difficile polymerase chain reaction (PCR) ($156), serum cytomegalovirus quantitative PCR ($1529), stool norovirus (NV) PCR ($4673), and stool culture ($6804). A time-to-event analysis found no significant difference in the length of hospital stay between patients with and without NV testing (P=.520). CONCLUSIONS: A stepwise testing strategy can reduce costs without compromising diagnostic yields. In the first-stage testing, we recommend assessment for C. difficile, cytomegalovirus, and food-borne bacterial pathogens. For persistent diarrheal episodes, second-stage evaluation should include stool NV PCR, Giardia/Cryptosporidium enzyme immunoassay, stool ova and parasite, reductions in immunosuppressive therapy, and possibly endoscopy. Although NV testing had a relatively low cost per FOR, we recommend NV testing during second-stage evaluation, as an NV diagnosis may not lead to changes in clinical management or further reductions in length of hospital stay.