RESUMEN
Wastewater-based surveillance (WBS) has become a widespread method to monitor transmission of SARS-CoV-2 and other human pathogens in Europe. We conducted a survey about WBS systems' objectives, approaches, representativeness and usefulness in 10 invited European countries in 2023, i.e. Austria, Belgium, Denmark, Finland, Greece, Hungary, Italy, Luxembourg, the Netherlands and Norway. All countries completed the study questionnaire about their SARS-CoV-2 WBS systems, and shared information about WBS of other pathogens as deemed relevant. SARS-CoV-2 WBS systems primarily monitored national and subnational trends (population coverage: 25-99%), and a majority (8/10) also tracked variant distribution. Nine of 10 countries reported that their SARS-CoV-2 WBS systems were representative of their population and all countries remarked that the findings were valuable for public health decision-making. Results were shared with relevant public health authorities and published via dedicated websites and/or dashboards. WBS systems of other pathogens were mostly in the early stages, with some countries implementing pilots. Notable exceptions were the well-established poliovirus surveillance systems in Finland, Italy and the Netherlands. This study brings understanding the diverse landscape of WBS in Europe, offering insights for future developments and collaborations. Furthermore, it highlights the need for further integration of WBS into other European surveillance systems.
Asunto(s)
COVID-19 , SARS-CoV-2 , Aguas Residuales , Humanos , Europa (Continente)/epidemiología , COVID-19/epidemiología , COVID-19/transmisión , Encuestas y Cuestionarios , Aguas Residuales/virología , Pandemias , Monitoreo Epidemiológico Basado en Aguas Residuales , Vigilancia de la Población/métodos , Neumonía Viral/epidemiología , Salud Pública , Infecciones por Coronavirus/epidemiología , BetacoronavirusRESUMEN
Legionnaires' disease (LD) is a severe pneumonia mainly caused by the bacterium Legionella pneumophila. Although many environmental sources of LD have been described, the sources of the majority of non-outbreak LD cases have not been identified. In several outbreaks in the Netherlands, wastewater treatment plants (WWTPs) were identified as the most likely source of infection. In this study, four criteria for Legionella growth and emission to air and surface waters were selected based on the literature and a risk matrix was drafted. An inventory was made of all WWTPs and their characteristics in the Netherlands. The risk matrix was applied to identify WWTPs at risk for Legionella growth and emission. Wastewater was collected at WWTPs with moderate to high risk for Legionella growth and emission. In 18% of the sampled WWTPs, Legionella spp. was detected using culture methods. The presented risk matrix can be used to assess the risks of Legionella growth and emission for WWTPs and support surveillance by prioritizing WWTPs. When Legionella is detected in the wastewater, it is recommended to take action to prevent emission to air or discharge on surface waters and, if possible, reduce the Legionella concentration.
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Legionella pneumophila , Legionella , Enfermedad de los Legionarios , Humanos , Aguas Residuales , Enfermedad de los Legionarios/epidemiología , Brotes de EnfermedadesRESUMEN
BackgroundSurveillance of SARS-CoV-2 in wastewater offers a near real-time tool to track circulation of SARS-CoV-2 at a local scale. However, individual measurements of SARS-CoV-2 in sewage are noisy, inherently variable and can be left-censored.AimWe aimed to infer latent virus loads in a comprehensive sewage surveillance programme that includes all sewage treatment plants (STPs) in the Netherlands and covers 99.6% of the Dutch population.MethodsWe applied a multilevel Bayesian penalised spline model to estimate time- and STP-specific virus loads based on water flow-adjusted SARS-CoV-2 qRT-PCR data for one to four sewage samples per week for each of the more than 300 STPs.ResultsThe model captured the epidemic upsurges and downturns in the Netherlands, despite substantial day-to-day variation in the measurements. Estimated STP virus loads varied by more than two orders of magnitude, from ca 1012 virus particles per 100,000 persons per day in the epidemic trough in August 2020 to almost 1015 per 100,000 in many STPs in January 2022. The timing of epidemics at the local level was slightly shifted between STPs and municipalities, which resulted in less pronounced peaks and troughs at the national level.ConclusionAlthough substantial day-to-day variation is observed in virus load measurements, wastewater-based surveillance of SARS-CoV-2 that is performed at high sampling frequency can track long-term progression of an epidemic at a local scale in near real time.
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COVID-19 , Aguas del Alcantarillado , Humanos , Países Bajos/epidemiología , SARS-CoV-2 , Monitoreo Epidemiológico Basado en Aguas Residuales , Teorema de Bayes , COVID-19/epidemiología , ARN ViralRESUMEN
Wastewater-based surveillance enables tracking of SARS-CoV-2 circulation at a local scale in near-real time. Here we investigate the relation between virus loads and the number of hospital admissions in the Netherlands. Inferred virus loads from August 2020 until February 2022 in each of the 344 Dutch municipalities are analysed in a Bayesian multilevel Poisson regression to relate virus loads to daily age-stratified (in groups of 20 years) hospital admissions. Covariates include municipal vaccination coverages stratified by age and dose (first, second, and booster) and prevalence of the circulating coronavirus variants (wildtype, Alpha, Delta, and Omicron (BA.1 and BA.2)). Our model captures the relation between hospital admissions and virus loads well. Estimated hospitalisation rates per 1,000,000 persons per day at a virus load of 1013 particles range from 0.18 (95 % Prediction Interval (PI): 0.046-0.48) in children (0-19 years) to 20.1 (95 % PI: 9.46-36.8) in the oldest age group (80 years and older) in an unvaccinated population with only wildtype SARS-CoV-2 circulation. The analyses indicate a nearly twofold (1.92 (95 % PI: 1.78-2.05)) decrease in the expected number of hospitalisations at a given virus load between the Alpha and the Omicron variant. Our analyses show that virus load estimates in wastewater are closely related to the expected number of hospitalisations and provide an attractive tool to detect increased SARS-CoV-2 circulation at a local scale, even when there are few hospital admissions. Our analyses enable integration of data at the municipality level into meaningful conversion rates to translate virus loads at a local level into expected numbers of hospital admissions, which would allow for a better interpretation of virus loads detected in wastewater.
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COVID-19 , Aguas Residuales , Adulto , Anciano de 80 o más Años , Niño , Humanos , Adulto Joven , Teorema de Bayes , COVID-19/epidemiología , Hospitalización , Hospitales , Países Bajos/epidemiología , SARS-CoV-2 , Recién Nacido , Lactante , Preescolar , AdolescenteRESUMEN
Wastewater-based epidemiological surveillance at municipal wastewater treatment plants has proven to play an important role in COVID-19 surveillance. Considering international passenger hubs contribute extensively to global transmission of viruses, wastewater surveillance at this type of location may be of added value as well. The aim of this study is to explore the potential of long-term wastewater surveillance at a large passenger hub as an additional tool for public health surveillance during different stages of a pandemic. Here, we present an analysis of SARS-CoV-2 viral loads in airport wastewater by reverse-transcription quantitative polymerase chain reaction (RT-qPCR) from the beginning of the COVID-19 pandemic in Feb 2020, and an analysis of SARS-CoV-2 variants by whole-genome next-generation sequencing from Sep 2020, both until Sep 2022, in the Netherlands. Results are contextualized using (inter)national measures and data sources such as passenger numbers, clinical surveillance data and national wastewater surveillance data. Our findings show that wastewater surveillance was possible throughout the study period, irrespective of measures, as viral loads were detected and quantified in 98.6 % (273/277) of samples. Emergence of SARS-CoV-2 variants, identified in 91.0 % (161/177) of sequenced samples, coincided with increases in viral loads. Furthermore, trends in viral load and variant detection in airport wastewater closely followed, and in some cases preceded, trends in national daily average viral load in wastewater and variants detected in clinical surveillance. Wastewater-based epidemiology at a large international airport is a valuable addition to classical COVID-19 surveillance and the developed expertise can be applied in pandemic preparedness plans for other (emerging) pathogens in the future.
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Aeropuertos , COVID-19 , SARS-CoV-2 , Carga Viral , Aguas Residuales , COVID-19/epidemiología , Aguas Residuales/virología , Países Bajos/epidemiología , Humanos , Monitoreo Epidemiológico Basado en Aguas Residuales , Monitoreo del Ambiente/métodosRESUMEN
Detection of Aichi virus in humans was initially reported in Japan in 1989. To establish a timeline for the prevalence of Aichi virus infection among humans in the Netherlands, we conducted molecular analysis of archival water samples from 1987-2000 and 2009-2012. Aichi virus RNA was detected in 100% (8/8) of sewage samples and 100% (7/7) of surface water samples collected during 1987-2000 and 100% (8/8) of sewage samples and 71% (5/7) of surface water samples collected during 2009-2012. Several genotype A and B Aichi virus lineages were observed over the 25-year period studied, but the time course of viral genetic diversity showed recent expansion of the genotype B population over genotype A. Our results show that Aichi virus has been circulating among the human population in the Netherlands since before its initial detection in humans was reported and that genotype B now predominates in this country.
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Agua Dulce/virología , Kobuvirus/genética , Aguas del Alcantarillado/virología , Microbiología del Agua , Teorema de Bayes , ADN Viral/genética , Variación Genética , Humanos , Modelos Genéticos , Tipificación Molecular , Países Bajos , Filogenia , Análisis de Secuencia de ADNRESUMEN
Hepatitis E virus genotype 3 (HEV-3) is a food-borne pathogen causative of hepatitis E infections in humans. In Europe, HEV-3 is mainly transmitted through the consumption of raw or undercooked pork. In order to determine the effectiveness of control measures that can be taken in the industry or by the consumer, it is pivotal to determine the infectivity of HEV present in pork products after thermal food-processing steps. First, we implemented a method for the detection of infectious HEV-3c and HEV-3e in a cell culture medium and in extracts from inoculated pork products. Next, we investigated the effect of the thermal inactivation of HEV by mimicking food-processing steps specific for dried sausage and liver homogenate matrices. After four weeks, HEV-inoculated dried sausage subjected to 21 °C or lower temperatures was still infectious. For the liver homogenate, the highest HEV-3c/e inactivation of the conditions tested was observed at 71 °C for five min or longer. Finally, our method was able to successfully detect and estimate viral loads of infectious HEV in naturally infected pig livers. Our data provide a basis for the future use of the quantitative microbial risk assessment of infectious HEV in pork products that are subjected to thermal food processing steps.
RESUMEN
The implementation and integration of wastewater-based epidemiology constitutes a valuable addition to existing pathogen surveillance systems, such as clinical surveillance for SARS-CoV-2. In the Netherlands, SARS-CoV-2 variant circulation is monitored by performing whole-genome sequencing on wastewater samples. In this manuscript, we describe the detection of an AY.43 lineage (Delta variant) amid a period of BA.5 (Omicron variant) dominance in wastewater samples from two wastewater treatment plants (WWTPs) during the months of August and September of 2022. Our results describe a temporary emergence, which was absent in samples from other WWTPs, and which coincided with peaks in viral load. We show how these lineage estimates can be traced back to lineage-specific substitution patterns. The absence of this variant from reported clinical data, but high associated viral loads suggest cryptic transmission. Our findings highlight the additional value of wastewater surveillance for generating insights into circulating pathogens.
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COVID-19 , Humanos , COVID-19/epidemiología , SARS-CoV-2/genética , Aguas Residuales , Monitoreo Epidemiológico Basado en Aguas ResidualesRESUMEN
Since the start of the COVID-19 pandemic in 2020, wastewater surveillance programs were established, or upscaled, in many countries around the world and have proven to be a cost-effective way of monitoring infectious disease pathogens. Many of these programs use RT-qPCR, and quantify the viral concentrations in samples based on standard curves, by including preparations of a reference material with known nucleic acid or virus concentrations in the RT-qPCR analyses. In high-throughput monitoring programs it is possible to combine data from multiple previous runs, circumventing the need for duplication and resulting in decreased costs and prolonged periods during which the reference material is obtained from the same batch. However, over time, systematic shifts in standard curves are likely to occur. This would affect the reliability and usefulness of wastewater surveillance as a whole. We aim to find an optimal combination of standard curve data to compensate for run-to-run measurement variance while ensuring enough flexibility to capture systematic longitudinal shifts. Based on more than 4000 observations obtained with the CDC N1 and N2 assays, taken as a part of the National Sewage Surveillance program at the Dutch National Institute for Public Health and the Environment, we show that seasonal and long-term shifts in RT-qPCR efficiency and sensitivity occur. We find that in our setting, using five days of standard-curve data to quantify, results in the least error prone curve or best approximation. This results in differences up to 100% in quantified viral loads when averaged out over a nationwide program of >300 treatment plants. Results show that combining standard curves from a limited set of runs can be a valid approach to quantification without obscuring the trends in the viral load of interest.
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COVID-19 , SARS-CoV-2 , Humanos , Aguas Residuales , Monitoreo Epidemiológico Basado en Aguas Residuales , Pandemias , Reproducibilidad de los Resultados , COVID-19/diagnóstico , COVID-19/epidemiología , Reacción en Cadena de la Polimerasa , Prueba de COVID-19RESUMEN
Non-travel-related hepatitis E virus (HEV) genotype 3 infections in persons in the Netherlands may have a zoonotic, foodborne, or water-borne origin. Possible reservoirs for HEV transmission by water, food, and animals were studied. HEV genotype 3/open reading frame 2 sequences were detected in 53% of pig farms, 4% of wild boar feces, and 17% of surface water samples. HEV sequences grouped within 4 genotype 3 clusters, of which 1 is so far unique to the Netherlands. The 2 largest clusters contained 35% and 43% of the animal and environmental sequences and 75% and 6%, respectively, of human HEV sequences obtained from a study on Dutch hepatitis E patients. This finding suggests that infection risk may be also dependent on transmission routes other than the ones currently studied. Besides the route of exposure, virus characteristics may be an important determinant for HEV disease in humans.
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Arvicolinae/virología , Virus de la Hepatitis E , Hepatitis E/transmisión , Ríos/virología , Sus scrofa/virología , Porcinos/virología , Zoonosis/transmisión , Crianza de Animales Domésticos , Animales , Heces/virología , Microbiología de Alimentos , Genotipo , Hepatitis E/epidemiología , Hepatitis E/virología , Virus de la Hepatitis E/clasificación , Virus de la Hepatitis E/genética , Virus de la Hepatitis E/aislamiento & purificación , Humanos , Países Bajos/epidemiología , Enfermedades de los Roedores/transmisión , Enfermedades de los Roedores/virología , Enfermedades de los Porcinos/epidemiología , Enfermedades de los Porcinos/transmisión , Enfermedades de los Porcinos/virología , Zoonosis/virologíaRESUMEN
Swimming in fecally contaminated recreational water may lead to gastrointestinal illness. A recreational water-associated outbreak of norovirus (NoV) infections affecting at least 100 people in The Netherlands occurred in August 2012. Questionnaire responses from patients indicated swimming in recreational lake Zeumeren as the most likely cause of illness. Most patients visited the lake during the weekend of 18â»19 August, during which the weather was exceptionally warm (maximum temperatures 32â»33 °C), and visitor numbers elevated. Patients, mostly children, became ill with gastroenteritis 1â»6 days (median 2 days) after exposure. Four stool samples from patients were NoV GI positive. Subsurface sandy soil from one of the beaches where most patients swam was NoV GI positive; the water sample was negative. The epidemiological curve and the timeline of investigation based on reported symptoms demonstrate the difficulty in discovering the source in recreational water outbreaks. A NoV outbreak in a recreational lake that is not subjected to external fecal contamination sources shows the need for active communication about human shedding of viruses during and after diarrheal episodes and the advice to refrain from swimming, even a few weeks after the symptoms have resolved.
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Infecciones por Caliciviridae/epidemiología , Gastroenteritis/epidemiología , Lagos/virología , Natación , Adolescente , Adulto , Infecciones por Caliciviridae/transmisión , Niño , Preescolar , Brotes de Enfermedades , Heces/virología , Femenino , Gastroenteritis/virología , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Países Bajos/epidemiología , Norovirus , Microbiología del Suelo , Microbiología del Agua , Adulto JovenRESUMEN
Pigs have been suggested to be a potential reservoir for locally acquired human hepatitis E virus (HEV) infections in the Netherlands. To study possible trends in HEV prevalence in the Dutch pig population, 97 pig farms have been screened for the presence of HEV in stools. The prevalence rate of HEV was estimated at 55% (53/97) in 2005, indicating a significant increase as compared to the prevalence rate of 22% (25/115) as was reported in 1999. The current data suggest that this increase is due to the inclusion of appropriate quality assurance controls such as internal amplification controls for RT-PCR. The abundant presence of pigs excreting HEV raises concerns on potential zoonotic transmission of the virus, either by exposure through the environment or by consumption of contaminated pork products. Moreover, one of the detected strains belonged to a European cluster which was not detected in the Netherlands before, suggesting that HEV strains spread through European countries. These data demonstrate the need to include appropriate controls in diagnostic assays, especially in complex matrices such as feces which are known to contain PCR inhibitory substances.
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Virus de la Hepatitis E/aislamiento & purificación , Hepatitis E/veterinaria , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/normas , Enfermedades de los Porcinos/epidemiología , Animales , Genotipo , Hepatitis E/virología , Humanos , Datos de Secuencia Molecular , Países Bajos/epidemiología , Filogenia , Prevalencia , Control de Calidad , Porcinos , ZoonosisRESUMEN
The intestinal parasites Cryptosporidium and Giardia cause gastro-enteritis in humans and can be transmitted via contaminated water. Oysters are filter feeders that have been demonstrated to accumulate pathogens such as Salmonella, Vibrio, norovirus and Cryptosporidium from contaminated water and cause foodborne infections. Oysters are economically important shellfish that are generally consumed raw. Commercial and non-commercial oysters (Crassostrea gigas) and oyster culture water from the Oosterschelde, The Netherlands, were examined for the presence of Cryptosporidium oocysts and Giardia cysts. Nine of 133 (6.7%) oysters from two non-commercial harvesting sites contained Cryptosporidium, Giardia or both. Six of 46 (13.0%) commercial oysters harboured Cryptosporidium or Giardia in their intestines. Data on the viability of (oo)cysts recovered from Oosterschelde oysters were not obtained, however viable (oo)cysts were detected in surface waters that enter the Oosterschelde oyster harvesting areas. The detection of Cryptosporidium and Giardia in oysters destined for human consumption has implications for public health only when human pathogenic (oo)cysts that have preserved infectivity during their stay in a marine environment are present. Our data suggest that consumption of raw oysters from the Oosterschelde may occasionally lead to cases of gastro-intestinal illness.
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Cryptosporidium/aislamiento & purificación , Contaminación de Alimentos/análisis , Parasitología de Alimentos , Giardia/aislamiento & purificación , Ostreidae/parasitología , Mariscos/parasitología , Animales , Seguridad de Productos para el Consumidor , Humanos , Países Bajos , Oocistos , Salud PúblicaRESUMEN
Urban canal swimming events are popular in the Netherlands. In 2015, two city canal swimming events took place, in Utrecht (Utrecht Singel Swim, USS) and in Amsterdam (Amsterdam City Swim, ACS). This prospective study characterizes the health risks associated with swimming in urban waters. Online questionnaires were sent to 160 (USS) and 2,692 (ACS) participants, with relatives of participants who did not swim completing the questionnaire as a control. Swimming water specimens and stool specimens of diarrheic participants in the ACS group were analysed. A total of 49% of USS and 51% of ACS swimmers returned their questionnaires. Nine percent of USS swimmers and 4% of non-swimmers reported gastrointestinal complaints (aRR 2.1; 95% CI: 0.3-16), while a total of 31% of ACS swimmers and 5% of non-swimmers reported gastrointestinal complaints (aRR 6.3; 95% CI: 4.1-9.5). AGI risk among ACS participants was directly related to increasing number of mouthfuls of water swallowed. Various norovirus genotypes were detected in five out of seven stool specimens taken from ACS participants and in all three tested ACS water samples. We conclude that the AGI risk among open-water swimmers in urban areas depends on the circumstances around the event. The epidemiological curve, the statistical association between swimming and AGI, and the microbiological evidence for norovirus in stool and water specimens suggest that AGI outbreak after the ACS event was due to water contamination by multiple norovirus strains, which is possibly linked to sewage overflow due to prior heavy rainfall. There is need for more targeted preventive measurements and recommendations for organizers, municipal authorities and participants to prevent this reoccurring in the future.
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Infecciones por Caliciviridae/epidemiología , Infecciones por Enterobacteriaceae/epidemiología , Enterobacteriaceae/aislamiento & purificación , Gastroenteritis/epidemiología , Gastroenteritis/microbiología , Norovirus/aislamiento & purificación , Natación , Adolescente , Adulto , Infecciones por Caliciviridae/virología , Brotes de Enfermedades/prevención & control , Brotes de Enfermedades/estadística & datos numéricos , Infecciones por Enterobacteriaceae/microbiología , Heces/microbiología , Femenino , Agua Dulce/microbiología , Agua Dulce/virología , Humanos , Masculino , Persona de Mediana Edad , Países Bajos/epidemiología , Estudios Prospectivos , Factores de Riesgo , Encuestas y Cuestionarios , Microbiología del Agua , Contaminación del Agua/efectos adversos , Calidad del Agua , Adulto JovenAsunto(s)
Monkeypox virus , Mpox , Humanos , Monkeypox virus/genética , Aguas Residuales , Países Bajos , Mpox/diagnóstico , ADN Viral/genéticaRESUMEN
Faecally impacted surface waters used for drinking water production may encompass risk for norovirus infections. To be able to assess a possible health risk, noroviruses should be quantified and fluctuations identified. In 2001, norovirus concentrations in the river Meuse displayed a seasonal distribution with high peaks during wintertime as determined by RT-PCR on serially diluted RNA. An intensified day-by-day sampling scheme in the winter of 2002/2003 revealed that the winter peak consisted of several peaks of varying duration and magnitude, possibly due to contamination events in the catchment. The highest estimated concentration was 1700 PCR-detectable units per litre (95% CI 250-8000), which if coinciding with failing treatment could lead to significant numbers in drinking water. Adaptive dynamic filtering was shown to adequately predict subsequent sample concentrations. If valid, such analyses could prove to be useful as early warning systems in risk management of water sources.
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Norovirus/aislamiento & purificación , Ríos/microbiología , Países Bajos , Probabilidad , Factores de TiempoRESUMEN
Human noroviruses cause gastroenteritis in humans, leading to high virus loads in sewage. Norovirus concentrations in raw and treated sewage samples from two sewage treatment plants (STP) were studied, along with virus removal and genetic diversity. Over one year, the average norovirus concentrations in raw sewage were approximately 10(5) pcr detectable units (pdu) per liter compared with 10(3) pdu/l of treated sewage. Similar sewage treatment processes at STP-A and STP-B led to 2.7 and 2.0 log(10)-units of virus removal, respectively. In total, 11 different norovirus variants were detected in 49 out of 53 sewage samples, with up to four different norovirus strains in a single sewage sample. Along with GGI.6 Sindlesham and GGII.2 Melksham, the GGIIb variant was one of the most prevalent noroviruses in both raw and treated sewage. This strain emerged among populations in Europe in 2000 and 2001. Treated sewage containing 10(2)-10(3) norovirus pdu is discharged into the surface water. The use of such fecally contaminated surface waters for shellfish culture, drinking water production and recreational purposes poses a potential health risk. We showed the presence of multiple norovirus strains in raw and treated sewage, confirming the need to clone before sequencing the RT-PCR products. Exposure to multiple norovirus strains in sewage contaminated food or water may lead to the occurrence of norovirus recombinants, which may be more virulent and pathogenic than the norovirus strains already circulating in the population.
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Norovirus/genética , ARN Viral/genética , Aguas del Alcantarillado/virología , Eliminación de Residuos Líquidos , Monitoreo del Ambiente , Variación Genética , Países Bajos , Norovirus/aislamiento & purificación , Filogenia , ARN Viral/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Aguas del Alcantarillado/análisisRESUMEN
Noroviruses are the most common agents causing outbreaks of viral gastroenteritis. Outbreaks originating from contaminated drinking water and from recreational waters have been described. Due to a lack of cell culture systems, noroviruses are detected mostly by molecular methods. Molecular detection assays for viruses in water are often repressed by inhibitory factors present in the environment, like humic acids and heavy metals. To study the effect of environmental inhibitors on the performance of nucleic acid sequence-based amplification (NASBA), we developed a real-time norovirus NASBA targeting part of the RNA-dependent RNA polymerase (RdRp) gene. Specificity of the assay was studied with 33 divergent clones that contained part of the targeted RdRp gene of noroviruses from 15 different genogroups. Viral RNA originated from commercial oysters, surface waters, and sewage treatment plants in The Netherlands. Ninety-seven percent of the clones derived from human noroviruses were detected by real-time NASBA. Two clones containing animal noroviruses were not detected by NASBA. We compared the norovirus detection by real-time NASBA with that by conventional reverse transcriptase PCR (RT-PCR) with large-volume river water samples and found that inhibitory factors of RT-PCR had little or no effect on the performance of the norovirus NASBA. This consequently resulted in a higher sensitivity of the NASBA assay than of the RT-PCR. We show that by combining an efficient RNA extraction method with real-time NASBA the sensitivity of norovirus detection in water samples increased at least 100 times, which consequently has implications for the outcome of the infectious risk assessment.
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Norovirus/aislamiento & purificación , ARN Polimerasa Dependiente del ARN/genética , Replicación de Secuencia Autosostenida/métodos , Animales , Humanos , Norovirus/enzimología , Norovirus/genética , Ostreidae/virología , ARN Viral/análisis , ARN Viral/aislamiento & purificación , Ríos/virología , Sensibilidad y Especificidad , Aguas del Alcantarillado/virologíaRESUMEN
Application of recent techniques to detect current pathogens in archival effluent samples collected and concentrated in 1987 lead to the characterization of norovirus GGII.6 Seacroft, unrecognized until 1990 in a clinical sample. Retrospective studies will likely increase our knowledge about waterborne transmission of emerging pathogens.