Prevalence of nonpolio enteroviruses in the sewage of Guangzhou city, China, from 2009 to 2012

Intensified Circulation of Echovirus 11 after the COVID-19 Pandemic in Poland: Detection of a Highly Pathogenic Virus Variant

After the first phase of the COVID-19 pandemic in Europe, a new highly pathogenic variant of echovirus 11 (E11) was detected. The aim of this study was to analyze the genetic diversity of Polish E11 environmental and clinical strains circulating between 2017 and 2023 as well as compare them with E11 strains isolated from severe neonatal sepsis cases reported in Europe between 2022 and 2023. Additionally, the study explores the effectiveness of environmental monitoring in tracking the spread of new variants. For this purpose, the complete sequences of the VP1 capsid protein gene were determined for 266 E11 strains isolated in Poland from 2017 to 2023, and phylogenetic analysis was performed. In the years 2017-2023, a significant increase in the detection of E11 strains was observed in both environmental and clinical samples in Poland. The Polish E11 strains represented three different genotypes, C3, D5 and E, and were characterized by a high diversity. In Poland, the intensive circulation of the new variant E11, responsible for severe neonatal infections with a high mortality in Europe, was detected in the years 2022-2023. This investigation demonstrates the important role of environmental surveillance in the tracking of enteroviruses circulation, especially in settings with limited clinical surveillance.

Analysis of the distribution characteristics of enterovirus types based on environmental surveillance from 2013 to 2021 in Fujian Province, China

Environmental surveillance (ES) is a useful approach for monitoring circulating viruses, including polioviruses (PVs) and non-polio enteroviruses (NPEVs). In this study, the results of nine years of ES from 2013 to 2021 at six sampling sites in three cities in Fujian Province, China, were summarized. It showed that the sewage samples contained abundant viruses, but the positive rate was affected by different sampling sites. From the 520 samples, 431 PVs, 1,713 NPEVs, and 281 human adenoviruses (HAdVs) were isolated. PV isolates had been markedly affected following the adjustment of the immunization strategy. All but one PV isolate were Sabin-like strains without wild PVs. One isolate was vaccine-derived PV type 3 with 10 variation points in the VP1 region. After May 2016, PV type 2 was no longer detected, and PV type 3 became a superior serotype. Of 1,713 NPEVs, 24 serotypes were identified, including echovirus11 (E11), E6, coxsackievirus B3 (CVB3), CVB5, E7, and E3 were the predominant serotypes (37.65%, 20.96%, 11.50%, 8.87%, 8.23%, and 7.06%, respectively). The temporal dynamic of the six common serotypes was inconsistent. E3 was frequently isolated, but the number of isolates was low, with no obvious peaks. E6, E7, and CVB3 exhibited periodic changes with a high peak every three to four years, and E11 only had one high peak lasting four years. Summer-fall peaks of the echoviruses and spring-winter peaks of CVB were observed in the monthly distribution of virus isolation. The infectious isolates of various serotypes of different species identified from the sewage samples showed that ES is an essential part of pathogen surveillance.

Prevalence of Non-Polio Enteroviruses in the Sewage of Guangzhou City, China, from 2013 to 2021

Continuous surveillance of enteroviruses (EVs) in urban domestic sewage can timely reflect the circulation of EVs in the environment and crowds, and play a predictive and early warning role in EV-related diseases. To better understand the long-term epidemiological trends of circulating EVs and EV-related diseases, we conducted a 9-year (2013 to 2021) surveillance study of non-polio EVs (NPEVs) in urban sewage in Guangzhou city, China. After concentrating and isolating the viruses from the sewage samples, NPEVs were detected and molecular typing was performed. Twenty-one different NPEV serotypes were identified. The most isolated EVs were echovirus 11 (E11), followed by coxsackievirus (CV) B5, E6, and CVB3. EV species B prevailed in sewage samples, but variations in the annual frequency of different serotypes were also observed in different seasons, due to spatial and temporal factors. E11 and E6 were detected continuously before 2017, and the number of isolates was relatively stable during the surveillance period. However, after their explosive growth in 2018 and 2019, their numbers suddenly decreased significantly. CVB3 and CVB5 had alternating trends; CVB5 was most frequently detected in 2013 to 2014 and 2017 to 2018, while CVB3 was most frequently detected in 2015 to 2016 and 2020 to 2021. Phylogenetic analysis showed that at least two different transmission chains of CVB3 and CVB5 were prevalent in Guangzhou City. Our results show that in the absence of a comprehensive and systematic EV-related disease surveillance system in China, environmental surveillance is a powerful and effective tool to strengthen and further investigate the invisible transmission of EVs in the population. IMPORTANCE This study surveilled urban sewage samples from north China for 9 years to monitor enteroviruses. Samples were collected, processed, and viral identification and molecular typing were performed. We detected 21 different non-polio enteroviruses (NPEVs) with yearly variations in prevalence and peak seasons. In addition, this study is very important for understanding the epidemiology of EVs during the COVID-19 pandemic, as the detection frequency and serotypes of EVs in sewage changed considerably around 2020. We believe that our study makes a significant contribution to the literature because our results strongly suggest that environmental surveillance is an exceptionally important tool, which can be employed to detect and monitor organisms of public health concern, which would otherwise be missed and under-reported by case-based surveillance systems alone.

A comparative study on environmental surveillance of enterovirus: Using a two-phase separation method and a filtration method with a mixed cellulose ester (MCE) membrane

This study aimed to compare the sensitivity of two-phase separation and the filtration method using a mixed cellulose ester (MCE) membrane to detect enteroviruses in sewage samples. From December 2015 to July 2016, four domestic sewage samples (1 L/sample) were collected monthly from the Guangzhou Liede Sewage Treatment Plant, and each sewage sample was divided into two aliquots (500 mL). The sewage sample was concentrated using the two-phase separation and the filtration method using an MCE membrane, and the treated solutions were inoculated into cells for enterovirus isolation. Polymerase chain reaction amplification, VP1 sequencing, and enterovirus molecular typing were performed on the positive isolates. The detection rates of poliovirus (PV) and non-polio enterovirus (NPEV) obtained using the filtration method using an MCE membrane were higher than those using the two-phase separation method. McNemar's test showed that the detection rates of PV, NPEV, type 1 Sabin-like (SL1), type 2 Sabin-like (SL2), and type 3 Sabin-like (SL3) strain were not statistically significant (P > 0.05). In Guangdong Province, China, the detection rates for PV and NPEV were 53.13% and 62.50% (20/32), respectively. Twenty-seven PVs were isolated, three highly variable strains of the type 1 vaccine, with seven nucleotide substitutions in the VP1 region, compared with the type 1 Sabin strains. Eighty-seven strains of NPEV were isolated and nine serotypes were identified, among which coxsackievirus B3 (CVB3), echovirus 6(E6), and echovirus 11(E11) were the dominant strains. The filtration method using an MCE membrane is more sensitive than two-phase separation and can be used as a robust, sensitive, and cost-effective method to isolate enteroviruses from sewage.

Looking into sewage: how far can metagenomics help to detect human enteric viruses?

The impact of human sewage on environmental and food contamination constitutes an important safety issue. Indeed, human sewage reflects the microbiome of the local population, and a variety of human viruses can be detected in wastewater samples. Being able to describe the diversity of viruses present in sewage will provide information on the health of the surrounding population health and will help to prevent further transmission. Metagenomic developments, allowing the description of all the different genomes present in a sample, are very promising tools for virome analysis. However, looking for human enteric viruses with short RNA genomes which are present at low concentrations is challenging. In this study we demonstrate the benefits of performing technical replicates to improve viral identification by increasing contig length, and the set-up of quality criteria to increase confidence in results. Our approach was able to effectively identify some virus sequences and successfully describe the viral diversity. The method yielded full genomes either for norovirus, enterovirus and rotavirus, even if, for these segmented genomes, combining genes remain a difficult issue. Developing reliable viromic methods is important as wastewater sample analysis provides an important tool to prevent further virus transmission by raising alerts in case of viral outbreaks or emergence.

Whole Genomic Sequence Analysis of Human Adenovirus Species C Shows Frequent Recombination in Tianjin, China

Human adenovirus species C (HAdV-C) is frequently detected in China and worldwide. For the first time, 16 HAdV-C strains were isolated from sewage water (14 strains) and hospitalised children with diarrhoea (2 strains,) in Tianjin, China. Nearly complete genome data were successfully obtained for these viruses. Subsequently, genomic and bioinformatics analyses of the 16 HAdV-C strains were performed. A phylogenetic tree of the complete HAdV-C genome divided these strains into three types: HAdV-C1, HAdV-C2, HAdV-C5. Phylogenetic analysis based on the fiber gene showed similar outcomes to analyses of the hexon gene and complete HAdV-C genomes, whereas the penton gene sequences showed more variation than previously reported. Furthermore, analysis of the whole-genome sequencing revealed seven recombination patterns transmitted in Tianjin, of which at least four patterns have not been previously reported. However, the penton base gene sequences of the HAdV-C species had significantly lower heterogeneity than those of the hexon and fiber gene sequences of recombinant isolates; that is, many strains were distinct in origin, but shared hexon and fiber genes. These data illustrate the importance of frequent recombination in the complexity of the HAdV-C epidemic in Tianjin, thus emphasising the necessity for HAdV-C sewage and virological monitoring in China.

Wastewater Surveillance for Infectious Disease: A Systematic Review

Wastewater surveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown to be a valuable source of information regarding SARS-CoV-2 transmission and coronavirus disease 2019 (COVID-19) cases. Although the method has been used for several decades to track other infectious diseases, there has not been a comprehensive review outlining all of the pathogens that have been surveilled through wastewater. Herein we identify the infectious diseases that have been previously studied via wastewater surveillance prior to the COVID-19 pandemic. Infectious diseases and pathogens were identified in 100 studies of wastewater surveillance across 38 countries, as were themes of how wastewater surveillance and other measures of disease transmission were linked. Twenty-five separate pathogen families were identified in the included studies, with the majority of studies examining pathogens from the family Picornaviridae, including polio and nonpolio enteroviruses. Most studies of wastewater surveillance did not link what was found in the wastewater to other measures of disease transmission. Among those studies that did, the value reported varied by study. Wastewater surveillance should be considered as a potential public health tool for many infectious diseases. Wastewater surveillance studies can be improved by incorporating other measures of disease transmission at the population-level including disease incidence and hospitalizations.

Capturing noroviruses circulating in the population: sewage surveillance in Guangdong, China (2013-2018)

Noroviruses (NoVs) are the leading cause of acute gastroenteritis (AGE) outbreaks. Since 2014, novel genetic variants of NoV have been continuously identified and have caused a sharp increase in the number of AGE outbreaks. The specific geographical distribution and expanding genetic diversity of NoV has posed a challenge to conventional surveillance. Here, we describe the long-term dynamic correlation between NoV distribution in sewage and in the local population through the molecular surveillance of NoV in Guangdong, 2013-2018. The relative viral loads of the GI and GII genotypes in sewage were calculated through RT-PCR. A high-throughput sequencing method and operational taxonomic unit (OTU) clustering pipeline were developed to illustrate the abundances of different genotypes and genetic variants in sewage. Our results showed that the NoV viral loads and the emergence of new variants in sewage were closely associated with NoV outbreak risks in the population. Compared with the outbreaks surveillance, the dominance of the newly emerged variants, GII.P17-GII.17 and GII.P16-GII.2, could be detected one or two months ahead in sewage of a hub city. In addition, the dynamics of pre-epidemic variants, which were rarely detected in clinics, could be captured through sewage surveillance, thus improving our understanding of the origin and evolution of these novel epidemic variants. Our data highlight that sewage surveillance could provide nearly real-time and high-throughput data on NoV circulation in the community. With the advances in sequencing techniques, the sewage surveillance system could also be extended to other related infectious diseases.

Prevalence and Bayesian Phylogenetics of Enteroviruses Derived From Environmental Surveillance Around Polio Vaccine Switch Period in Shandong Province, China

We present the results of environmental surveillance for poliovirus (PV) and non-poliovirus (NPEV) around the switch from trivalent to bivalent oral polio-vaccine (OPV) which occurred in China in May 2016. Sewage samples were collected in Jinan and Linyi city from 2015 to 2017. Enterovirus (EV) isolation, VP1 amplification, Sanger sequencing, and phylogenetic analyses were performed. Among105 sewage samples (36 in Jinan and 69 in Linyi), 101 were positive for EV, with 74.3% (78/105) PV-positive samples and 90.5% (95/105) NPEV-positive samples. A total of 893 EV isolates were obtained, including 326 (36.5%) PVs and 567 (63.5%) NPEVs. Echovirus (E) -11 was the most common serotype out of 18 detected NPEV types (120/567), followed by E-3 (75/567) and E-6 (74/567). PV2 vanished and PV3 came to be the ascendant PV type in sewage after May 2016. Eight PV isolates were judged as pre-vaccine-derived poliovirus (pre-VDPV) and no VDPV or wild PV isolates were monitored. Bayesian phylogenetics demonstrated global E-11 originated in 1876 and evolved with the estimated rate of 4.63 × 10^-3 nucleotide substitutions per site per year (s/s/y). Multiple circulating clusters that originated at different times were coexisting in Shandong province. The most recently common ancestor of global coxsackievirus B5 could date back to 1867, at the evolutionary rate of 3.95 × 10^-3 s/s/y. In conclusion, our study described the changes of PVs and NPEVs around the polio vaccine switch period and provided meaningful global molecular epidemiological data for further studies of EV-related diseases among the population.

Detection of enteroviruses in urban sewage by next generation sequencing and its application in environmental surveillance

Environmental surveillance has been used successfully in monitoring enterovirus (EV) circulation; however cell culture method may introduce a selective bias in those EV strains that are recovered from the environment. In this study, urban sewage samples were collected monthly in Jinan, China in 2018 and concentrated via membrane adsorption/elution method. A P1 seminested RT-PCR (RT-snPCR) and NGS method was developed, by which amplicons of 4000 nucleotide in length covering the entire P1 region of EVs were obtained from sewage concentrates and were further analyzed by next generation sequencing (NGS). In addition, for each sewage concentrate, two other assays - cell culture and NGS based partial VP1 amplicon sequencing - were conducted in parallel and compared. The results showed that the P1 RT-snPCR and NGS method generated the most data, with 32 serotypes identified belonging to species EV-A (n = 11), EV-B (n = 14), and EV-C (n = 7). These serotypes covered all those detected from the methods of cell culture (n = 10) and partial VP1 amplicon sequencing (n = 16). EV serotypes from acute flaccid paralysis surveillance correlated with those from sewage. Phylogenetic analysis on coxsackievirus B5, a common pathogen of meningitis, revealed close genetic relationship between environmental and clinical sequences. These results demonstrate sewage contains different EVs related to a variety of diseases. Traditional cell culture method underestimates the existence of some serotypes. NGS based environmental surveillance provides data which are consistent with those from clinical diseases, greatly improves our understanding on the actual circulation in the population, and should be encouraged for public health surveillance.

Tracking echovirus eleven outbreaks in Guangdong, China: a metatranscriptomic, phylogenetic, and epidemiological study

In April 2019, a suspect cluster of enterovirus cases was reported in a neonatology department in Guangdong, China, resulting in five deaths. We aimed to investigate the pathogen profiles in fatal cases, the circulation and transmission pattern of the viruses by combining metatranscriptomic, phylogenetic, and epidemiological analyses. Metatranscriptomic sequencing was used to characterize the enteroviruses. Clinical and environmental surveillance in the local population was performed to understand the prevalence and genetic diversity of the viruses in the local population. The possible source(s), evolution, transmission, and recombination of the viruses were investigated by incorporating genomes from the current outbreak, from local retrospective surveillance, and from public databases. Metatranscriptomic analysis identified Echovirus 11 (E11) in three fatal cases. Seroprevalence of neutralization antibody to E11 was 35 to 44 per cent in 3–15 age groups of general population, and the viruses were associated with various clinical symptoms. From the viral phylogeny, nosocomial transmissions were identified and all E11 2019 outbreak strains were closely related with E11 strains circulating in local population 2017–19. Frequent recombination occurred among the 2019 Guangdong E11 outbreak strains and various genotypes in enterovirus B species. This study provides an example of combining advanced genetic technology and epidemiological surveillance in pathogen diagnosis, source(s), and transmission tracing during an infectious disease outbreak. The result highlights the hidden E11 circulation and the risk of viral transmission and infection in the young age population in China. Frequent recombination between Guangdong-like strains and other enterovirus genotypes also implies the prevalence of these emerging E11 strains.

Environmental Surveillance Can Dynamically Track Ecological Changes in Enteroviruses

Environmental surveillance can be used to trace enteroviruses shed from human stool using a sewer network that is independent of symptomatic or asymptomatic infection. In this study, the local transmission of enteroviruses was analyzed using two wastewater treatment plants, which were relatively close to each other (15 km), designated as sentinels. Influent was collected at both sentinels once a month from 2013 to 2016, and viruses were isolated. Using neutralizing tests with type-specific polyclonal antisera and molecular typing, 933 isolates were identified as enteroviruses. Our results showed that the frequency of virus isolation varied for each serotype at the two sentinels in a time-dependent manner. Because echovirus 11 (Echo11) and coxsackievirus B5 isolates showed a high frequency and were difficult to distinguish, they were further grouped into various lineages based on the VP1 amino acid sequences. The prevalence of each lineage was visualized using multidimensional scaling. The results showed that Echo11 isolates of the same lineage were isolated continuously, similar to coxsackievirus B5 isolates of three lineages. Conversely, Echo1, Echo13, Echo18, Echo19, Echo20, Echo29, and Echo33 were isolated only once each. Our findings suggested that if an enterovirus is imported into the population, it may result in small-scale transmission, whereas if there are initially many infected individuals, it may be possible for the virus to spread to a wide area, beyond the local community, over time. In addition, our findings could provide insights into risk assessment of transmission for importation of poliovirus in polio-free countries and regions.IMPORTANCE In this study, we showed that environmental enterovirus surveillance can be used to monitor the propagation of nonpolio enteroviruses in addition to poliovirus detection. Since epidemiological studies of virus transmission based on the past were performed using specimens from humans, there were limitations to research design, such as specimen collection for implementation on a large-scale target population. However, environmental monitoring can dynamically track the ecological changes in enteroviruses in the region by monitoring viruses in chronological order and targeting the population within the area by monitoring viruses over time. We observed differences in the transmission of echovirus 11 and coxsackievirus B5 in the region according to lineage in a time-dependent manner and with a multidimensional scaling pattern.

Environmental Surveillance of Human Enteroviruses in Córdoba City, Argentina: Prevalence and Detection of Serotypes from 2009 to 2014

Environmental surveillance is an effective approach to investigate the circulation of human enteroviruses (EVs) in the population. EVs excreted by patients who present diverse clinical syndromes can remain infectious in the environment for several weeks, and limited data on circulating environmental EVs are available. A 6-year (2009-2014) surveillance study was conducted to detect non-polio enteroviruses (NPEVs) in the urban sewage of Cordoba city, Argentina. Echovirus 6 (E-6) was the most prevalent (28%), followed by E-14 (17%), E-16 (14%), Coxsackievirus (CV) A9 (11%), E-20 (9%), and CVA24 (6%). Other minority serotypes (E-7, E-13, E-21, E-25, and CVB4) were found, which together represented 14% of the total. In the absence of a systematic EV disease surveillance system, the detection and characterization of sewage-borne NPEVs will help us better understand the changes in EV disease trends and the epidemic background of circulating EVs, which could help interpret the EV trends and warn of future outbreaks in this area.

Environmental Surveillance of Enteroviruses in Central Argentina: First Detection and Evolutionary Analyses of E14

Environmental surveillance is an effective approach to investigate the circulation of human enteroviruses in the population. Enteroviruses E14, CVA9, E-6, E16, E20, E25, E13, and CVA24 were detected in sewage and a watercourse in central Argentina. E14 was the most frequent serotype and was found for the first time in environmental samples in our region. Phylogenetic and coalescence analyses showed at least two recent introduction events.

Recombination analysis of coxsackievirus B5 genogroup C

Coxsackievirus B5 (CVB5) is a member of the species Enterovirus B of the genus Enterovirus, family Picornaviridae. Based on its VP1 sequence, CVB5 is divided into four genogroups: A, B, C, and D. From 2002 to 2012, CVB5 serotype genogroup C caused an outbreak of aseptic meningitis in China. In order to study the evolution of CVB5 genogroup C, phylogenetic and recombination analysis was performed using the 399 available enterovirus B genome sequences in the GenBank database. The results indicated that 10 strains of CVB5 serotype genogroup C resulted from recombination between members of genogroup B and echovirus serotype E6, and another 5 strains resulted from recombination between members of genogroup C and serotype CVB4. These recombination events were confirmed by phylogenetic analysis.

A cluster of coxsackievirus A21 associated acute respiratory illness: the evidence of efficient transmission of CVA21

In March 2016, a cluster of unexplained respiratory illnesses was reported by the acute respiratory infections (ARI) surveillance system of Guangdong Province, China. Twenty-three high school students and one teacher from the four neighboring classes were admitted to a hospital. CVA21 was found in eight of fourteen patients. Phylogenetic analysis suggested that the CVA21 outbreak was most likely caused by transmission of the virus from person to person. This is the first report of an ARI outbreak caused by CVA21, which suggests that CVA21 has the potential to be transmitted efficiently from person to person and should be closely monitored by clinicians and public health agencies.

One-year Survey of human enteroviruses from sewage and the factors affecting virus adsorption to the suspended solids

This study described the results of environmental enterovirus surveillance conducted in Shandong Province of China in 2013. Altogether 39 sewage samples were collected and 873 enterovirus isolates (including 334 polioviruses) belonging to 22 serotypes were obtained. Echovirus (E) -7, coxsackievirus (CV) -B5, E-11, E-6, and E-3 were the most commonly detected non-polio enterovirus serotypes, and phylogeny of E-7 and CV-B5 was described. The numbers of isolates of different serotypes from sewage supernatant were compared with those from the solids. Interestingly, dramatic divergence was observed between the supernatant and solids origin for the serotypes of E-3 and E-6, which were prone to the solids and supernatant, respectively. A following adsorption test with E-3 and E-6 added sewage specimens confirmed the different preference. Furthermore, the adsorption of Sabin poliovirus type 1 to the solids under different conditions was investigated, and the results showed that acid medium, cold temperature, and high solids concentration facilitated the viral adsorption to the solids, whereas change of virus titer did not influence the proportion of adsorption. These results highlighted the importance of combining the enterovirus isolates from the supernatant and solids together in environmental surveillance so as to better understand the local circulation of different serotypes.

High Incidence of Mammalian Orthoreovirus Identified by Environmental Surveillance in Taiwan

Wild poliovirus (WPV) persists in diverse locales worldwide, spreading outward from endemic areas. In response to the international threat of WPV transmission and changes in the national vaccination policy, we established an environmental surveillance system to monitor the circulation of wild and vaccine-related poliovirus in Taiwan. From July 2012 to December 2013, we collected sewage specimens every month from 10 sewage treatment plants located throughout Taiwan. The specimens were concentrated by the two-phase separation method and then inoculated into L20B, RD, and A549 cells for virus isolation. Viral isolates were identified and serotyped by immunofluorescence assay or molecular analysis. A total of 300 sewage samples were collected, and the results showed 163 samples (54.3%) were positive for virus, and 268 isolates were identified. Among these, 75 samples (25%) were positive for enterovirus (EV), but no poliovirus was found. In addition, 92 isolates were identified as enteroviruses and the most common serotypes were coxsackievirus B4, coxsackievirus B3, and coxsackievirus B2. Interestingly, 102 (34%) and 82 (27.3%) specimens were positive for mammalian orthoreovirus (MRV) and adenovirus, respectively. This study confirmed that sewage surveillance can be a useful additional modality for monitoring the possible presence of wild-type or vaccine-derived poliovirus in wastewater, and can indicate the current types of viruses circulating in the population. Furthermore, since MRV was found in children with acute necrotizing encephalopathy and meningitis, the high incidence of MRV detected by environmental surveillance warrants further investigation.

Environmental surveillance of human enteroviruses in Shandong Province, China, 2008 to 2012: serotypes, temporal fluctuation, and molecular epidemiology

Environmental surveillance is an effective approach in investigating the circulation of polioviruses (PVs) and other human enteroviruses (EVs) in the population. The present report describes the results of environmental surveillance conducted in Shandong Province, China, from 2008 to 2012. A total of 129 sewage samples were collected, and 168 PVs and 1,007 nonpolio enteroviruses (NPEVs) were isolated. VP1 sequencing and typing were performed on all isolates. All PV strains were Sabin-like, with the numbers of VP1 substitutions ranging from 0 to 7. The NPEVs belonged to 19 serotypes, and echovirus 6 (E6), E11, coxsackievirus B3 (CVB3), E3, E12, and E7 were the six main serotypes, which accounted for 18.3%, 14.8%, 14.5%, 12.9%, 9.0%, and 5.7% of NPEVs isolated, respectively. Typical summer-fall peaks of NPEV were observed in the monthly distribution of isolation, and an epidemic pattern of annual circulation was revealed for the common serotypes. Phylogenetic analysis was performed on environmental CVB3 and E3 strains with global reference strains and local strains from aseptic meningitis patients. Shandong strains formed distinct clusters, and a close relationship was observed between local environmental and clinical strains. As an EV-specific case surveillance system is absent in China and many other countries, continuous environmental surveillance should be encouraged to investigate the temporal circulation and phylogeny of EVs in the population.

Sporadic isolation of sabin-like polioviruses and high-level detection of non-polio enteroviruses during sewage surveillance in seven Italian cities, after several years of inactivated poliovirus vaccination

Sewage surveillance in seven Italian cities between 2005 and 2008, after the introduction of inactivated poliovirus vaccination (IPV) in 2002, showed rare polioviruses, none that were wild-type or circulating vaccine-derived poliovirus (cVDPV), and many other enteroviruses among 1,392 samples analyzed. Two of five polioviruses (PV) detected were Sabin-like PV2 and three PV3, based on enzyme-linked immunosorbent assay (ELISA) and PCR results. Neurovirulence-related mutations were found in the 5'noncoding region (5'NCR) of all strains and, for a PV2, also in VP1 region 143 (Ile>Thr). Intertypic recombination in the 3D region was detected in a second PV2 (Sabin 2/Sabin 1) and a PV3 (Sabin 3/Sabin 2). The low mutation rate in VP1 for all PVs suggests limited interhuman virus passages, consistent with efficient polio immunization in Italy. Nonetheless, these findings highlight the risk of wild or Sabin poliovirus reintroduction from abroad. Non-polio enteroviruses (NPEVs) were detected, 448 of which were coxsackievirus B (CVB) and 294 of which were echoviruses (Echo). Fifty-six NPEVs failing serological typing were characterized by sequencing the VP1 region (nucleotides [nt] 2628 to 2976). A total of 448 CVB and 294 Echo strains were identified; among those strains, CVB2, CVB5, and Echo 11 predominated. Environmental CVB5 and CVB2 strains from this study showed high sequence identity with GenBank global strains. The high similarity between environmental NPEVs and clinical strains from the same areas of Italy and the same periods indicates that environmental strains reflect the viruses circulating in the population and highlights the potential risk of inefficient wastewater treatments. This study confirmed that sewage surveillance can be more sensitive than acute flaccid paralysis (AFP) surveillance in monitoring silent poliovirus circulation in the population as well as the suitability of molecular approaches to enterovirus typing.

Removal properties of human enteric viruses in a pilot-scale membrane bioreactor (MBR) process

In order to evaluate removal properties of human enteric viruses from wastewater by a membrane bioreactor (MBR), influent, anoxic and oxic mixed liquor, and membrane effluent samples were collected in a pilot-scale anoxic-oxic MBR process for 16 months, and concentrations of enteroviruses, norovirus GII, and sapoviruses were determined by real-time PCR using murine norovirus as a process control. Mixed liquor samples were separated into liquid and solid phases by centrifugation, and viruses in the bulk solution and those associated with mixed liquor suspended solids (MLSS) were quantified. Enteroviruses, norovirus GII, and sapoviruses were detected in the influent throughout the sampling period (geometrical mean, 4.0, 3.1, and 4.4 log copies/mL, respectively). Enterovirus concentrations in the solid phase of mixed liquor were generally lower than those in the liquid phase, and the mean log reduction value between influent and anoxic mixed liquor was 0.40 log units. In contrast, norovirus GII and sapovirus concentrations in the solid phase were equal to or higher than those in the liquid phase, and higher log reduction values (1.3 and 1.1 log units, respectively) were observed between influent and anoxic mixed liquor. This suggested that enteroviruses were less associated with MLSS than norovirus GII and sapoviruses, resulting in lower enterovirus removal in the activated sludge process. Enteroviruses and norovirus GII were detected in the MBR effluent but sapoviruses were not in any effluent samples. When MLSS concentration was reduced to 50-60% of a normal operation level, passages of enteroviruses and norovirus GII through a PVDF microfiltration membrane were observed. Since rejection of viruses by the membrane was not related to trans-membrane pressure which was monitored as a parameter of membrane fouling, the results indicated that adsorption to MLSS plays an important role in virus removal by an MBR, and removal properties vary by viruses reflecting different adsorptive behavior to MLSS. Our observations suggested that sapoviruses are more associated with MLSS and removed more efficiently than enteroviruses and norovirus GII.

Elucidation of echovirus 30's origin and transmission during the 2012 aseptic meningitis outbreak in Guangdong, China, through continuing environmental surveillance

An aseptic meningitis outbreak occurred in Luoding City of Guangdong, China, in 2012, and echovirus type 30 (ECHO30) was identified as the major causative pathogen. Environmental surveillance indicated that ECHO30 was detected in the sewage of a neighboring city, Guangzhou, from 2010 to 2012 and also in Luoding City sewage samples (6/43, 14%) collected after the outbreak. In order to track the potential origin of the outbreak viral strains, we sequenced the VP1 genes of 29 viral strains from clinical patients and environmental samples. Sequence alignments and phylogenetic analyses based on VP1 gene sequences revealed that virus strains isolated from the sewage of Guangzhou and Luoding cities matched well the clinical strains from the outbreak, with high nucleotide sequence similarity (98.5% to 100%) and similar cluster distribution. Five ECHO30 clinical strains were clustered with the Guangdong environmental strains but diverged from strains from other regions, suggesting that this subcluster of viruses most likely originated from the circulating virus in Guangdong rather than having been more recently imported from other regions. These findings underscore the importance of long-term, continuous environmental surveillance and genetic analysis to monitor circulating enteroviruses.