Discharge of inadequately treated human wastewater into surface waters used for recreation, drinking water, irrigation and shellfish cultivation may present a public health hazard due to the ...potential shedding of high concentrations of pathogenic viruses from the human gastrointestinal tract. Human adenovirus (HAdV) and human polyomavirus (HPyV) are ubiquitous in humans and have excellent survival characteristics in the environment, so are potential candidates for indicators of human sewage contamination. Using qPCR assays, the prevalence and quantity of HAdV and HPyV JC and BK were determined in influent and effluent wastewater and receiving waters (river, urban stream, estuarine), then compared with norovirus (NoV) presence, a significant human pathogen which is not necessarily ubiquitously excreted into the environment. HAdV and HPyV were frequently detected in high concentrations in wastewater and wastewater-contaminated waters confirming their use as potential indicators for the presence of human sewage. Overall, there was a correlation between the presence of HAdV and HPyV with NoV but there were some notable exceptions including the higher frequency of NoV compared to HAdV and HPyV in estuarine waters impacted by wastewater overflows. We found that HAdV and HPyV detection by qPCR was a suitable tool for evaluating water quality and that their detection can aid in determining pollution sources, thus providing useful information for health risk assessments.
•HAdV and HPyV prevalence in environmental matrices were determined by qPCR.•HAdV and HPyV were suitable as human sewage indicators.•NoV were more frequently detected in estuarine water than HAdV and HPyV.•NoV were more frequently detected in urban stream water than HAdV and HPyV.•No strong correlations between different virus concentrations were observed.
Human adenovirus (AdV and AdV species F), enterovirus (EV) and norovirus (NoV) concentrations entering wastewater treatment plants (WWTP) serving different-sized communities, and effectiveness of ...different treatment processes in reducing concentrations were established. Data was combined to create a characteristic and unique descriptor of the individual viral composition and termed as the sample virus profile.
Virus profiles were generally independent of population size and treatment process (moving bed biofilm reactors, activated sludge, waste stabilisation ponds). AdV and EV concentrations in wastewater were more variable in small (<4000) and medium-sized (10,000–64,000) WWTP than in large-sized (>130,000 inhabitants) plants. AdV and EV concentrations were detected in influent of most WWTP (AdV range 1.00–4.08
log
10 infectious units (IU)/L, 3.25–8.62
log
10 genome copies/L; EV range 0.7–3.52
log
10 plaque forming units (PFU)/L; 2.84–6.67
log
10 genome copies/L) with a reduced median concentration in effluent (AdV range 0.70–3.26
log
10 IU/L, 2.97–6.95
log
10 genome copies/L; EV range 0.7–2.15 log
10PFU/L, 1.54–5.28
log
10 genome copies/L). Highest culturable AdV and EV concentrations in effluent were from a medium-sized WWTP. NoV was sporadic in all WWTP with GI and GII concentrations being similar in influent (range 2.11–4.64 and 2.19–5.46
log
10 genome copies/L) as in effluent (range 2.18–5.06 and 2.88–5.46
log
10 genome copies/L).
Effective management of WWTP requires recognition that virus concentration in influent will vary – particularly in small and medium plants. Irrespective of treatment type, culturable viruses and NoV are likely to be present in non-disinfected effluent, with associated human health risks dependent on concentration and receiving water usage.
► Influent virus concentrations were independent of population size served by the WWTP. ► Small WWTP were characterised by variable virus concentrations with sporadic spikes. ► NoV prevalence was sporadic in both influent and effluent wastewater. ► A similar NoV concentration range was found in influent and effluent wastewater. ► Irrespective of treatment type, viable viruses are likely to be present in effluent.
BackgroundNoroviruses (NoVs) are the most common cause of viral gastroenteritis. Their high incidence and importance in health care facilities result in a great impact on public health. Studies from ...around the world describing increasing prevalence have been difficult to compare because of differing nomenclatures for variants of the dominant genotype, GII.4. We studied the global patterns of GII.4 epidemiology in relation to its genetic diversity MethodsData from NoV outbreaks with dates of onset from January 2001 through March 2007 were collected from 15 institutions on 5 continents. Partial genome sequences (n=775) were collected, allowing phylogenetic comparison of data from different countries ResultsThe 15 institutions reported 3098 GII.4 outbreaks, 62% of all reported NoV outbreaks. Eight GII.4 variants were identified. Four had a global distribution—the 1996, 2002, 2004, and 2006b variants. The 2003Asia and 2006a variants caused epidemics, but they were geographically limited. Finally, the 2001Japan and 2001Henry variants were found across the world but at low frequencies ConclusionsNoV epidemics resulted from the global spread of GII.4 strains that evolved under the influence of population immunity. Lineages show notable (and currently unexplained) differences in geographic prevalence. Establishing a global NoV network by which data on strains with the potential to cause pandemics can be rapidly exchanged may lead to improved prevention and intervention strategies
Aims: To determine the suitability of murine norovirus (MNV) as a surrogate for human norovirus (HuNoV) in heat inactivation studies.
Methods and Results: MNV, hepatitis A virus (HAV) and HuNoV ...genogroup I and II (GI and GII) specific real‐time quantitative reverse transcription (qRT)‐PCR assays were used to determine the effects of heat exposure (63 and 72°C) for up to 10 min in water and milk. Using culture assays, MNV and HAV showed similar reductions in infectivity over time. Both HuNoV GI and GII showed lower log reductions in qRT‐PCR titre following heat exposure than either MNV or HAV. No significant protective effect of milk was observed for any virus.
Conclusions: MNV is as suitable a surrogate for HuNoV as HAV. In heat inactivation studies at 63 and 72°C, qRT‐PCR results indicate that HuNoV is less susceptible to heat than either HAV or MNV and so neither virus may be an appropriate surrogate for HuNoV.
Significance and Impact of the Study: Caution should be used when extrapolating surrogate virus data for HuNoV. Although not conclusive, our results suggest that HuNoV may be more resistant to heat than either HAV or MNV.
The etiology of an outbreak of gastroenteritis in humans cannot always be determined, and ∼25% of outbreaks remain unsolved in New Zealand. It is hypothesized that novel viruses may account for a ...proportion of unsolved cases, and new unbiased high-throughput sequencing methods hold promise for their detection. Analysis of the fecal metagenome can reveal the presence of viruses, bacteria, and parasites which may have evaded routine diagnostic testing. Thirty-one fecal samples from 26 gastroenteritis outbreaks of unknown etiology occurring in New Zealand between 2011 and 2012 were selected for de novo metagenomic analysis. A total data set of 193 million sequence reads of 150 bp in length was produced on an Illumina MiSeq. The metagenomic data set was searched for virus and parasite sequences, with no evidence of novel pathogens found. Eight viruses and one parasite were detected, each already known to be associated with gastroenteritis, including adenovirus, rotavirus, sapovirus, and Dientamoeba fragilis. In addition, we also describe the first detection of human parechovirus 3 (HPeV3) in Australasia. Metagenomics may thus provide a useful audit tool when applied retrospectively to determine where routine diagnostic processes may have failed to detect a pathogen.
In July 2006, public health services investigated an outbreak of acute gastroenteritis among staff and visitors of a popular ski resort in southern New Zealand. The source of the outbreak was a ...drinking water supply contaminated by human sewage. The virological component of the investigation played a major role in confirming the source of the outbreak. Drinking water, source stream water, and 31 fecal specimens from gastroenteritis outbreak cases were analyzed for the presence of norovirus (NoV). Water samples were concentrated by ultrafiltration, and real-time reverse transcription-PCR (RT-PCR) was used for rapid detection of NoV from both water and fecal samples. The implicated NoV strain was further characterized by DNA sequencing. NoV genogroup GI/5 was identified in water samples and linked case fecal specimens, providing clear evidence of the predominant pathogen and route of exposure. A retrospective cohort study demonstrated that staff who consumed drinking water from the resort supply were twice as likely to have gastroenteritis than those who did not. This is the first time that an outbreak of gastroenteritis in New Zealand has been conclusively linked to NoV detected in a community water supply. To our knowledge, this is the first report of the use of ultrafiltration combined with quantitative real-time RT-PCR and DNA sequencing for investigation of a waterborne NoV outbreak.
Quantitative real-time reverse transcription PCR (qRT-PCR) and cell culture (50% tissue culture infectious dose TCID50) were used to determine the effect of heat treatments on norovirus and hepatitis ...A virus (HAV) in the New Zealand Greenshell mussel (Perna canaliculus). Since it is common practice to cook mussels until the shells open, internal temperatures and opening times of mussels on boiling and steaming were determined at regular time intervals. Fifty mussels in batches of six were exposed to boiling and steaming. A mean internal temperature of 90°C (recommended for virus inactivation when maintained for 90 s) was reached after boiling for 170 s, with all 50 mussels open at 210 s. For steaming, the mean internal temperature achieved was only 83°C after 300 s, and all 50 mussels were open. When mussels were steamed for 180 s (mean internal temperature of 63°C), a significant 1.5-log decrease in the HAV titer (log TCID50) was observed. Following the immersion of mussels in boiling water for 180 s (mean internal temperature of 92°C), no viable HAV was detected. For both boiling and steaming experiments, there was no significant change in the norovirus or HAV qRT-PCR titers compared with the controls. Our results show that when New Zealand Greenshell mussels open on heating, their internal temperature may not reach the parameters required for virus inactivation. Immersion for a minimum of 3 min in boiling water rather than steaming is recommended to reduce the risk of viral foodborne illness from contaminated shellfish.
Background. Previously reported outbreaks of norovirus gastroenteritis associated with aircraft have been limited to transmission during a single flight sector. During October 2009, an outbreak of ...diarrhea and vomiting occurred among different groups of flight attendants who had worked on separate flight sectors on the same airplane. We investigated the cause of the outbreak and whether the illnesses were attributable to work on the airplane. Methods. Information was obtained from flight attendants on demographic characteristics, symptoms, and possible transmission risk factors. Case patients were defined as flight attendants with diarrhea or vomiting <51 hours after the end of their first flight sector on the airplane during 13—18 October 2009. Stool samples were tested for norovirus RNA. Results. A passenger had vomited on the Boeing 777-200 airplane on the 13 October flight sector. Sixty-three (82%) of 77 flight attendants who worked on the airplane during 13—18 October provided information, and 27 (43%) met the case definition. The attack rate among flight attendants decreased significantly over successive flight sectors from 13 October onward (P <.001). Working as a supervisor was independently associated with development of illness (adjusted odds ratio, 5.8; 95% confidence interval, 1.3—25.6). Norovirus genotype GI.6 was detected in stool samples from 2 case patients who worked on different flight sectors. Conclusions. Sustained transmission of norovirus is likely to have occurred because of exposures on this airplane during successive flight sectors. Airlines should make provision for adequate disinfection of airplanes with use of products effective against norovirus and other common infectious agents after vomiting has occurred.
Noroviruses (NV) and hepatitis A virus (HAV) are foodborne enteric viruses associated with outbreaks of disease following consumption of raw or lightly cooked bivalve shellfish. Marinated mussels are ...a popular delicacy, but there is no published information on whether enteric viruses survive the marination process. The survival and persistence of HAV, NV, and a surrogate calicivirus, feline calicivirus (FCV), in marinated mussels over time was determined. NV, HAV, and FCV were inoculated into marinated mussels and marinade liquid and then held at 4°C for up to 4 weeks. Survival of HAV and FCV was quantified by determining the 50% tissue culture infectious dose (TCID50), and these results were correlated with those of the reverse transcription (RT)-PCR assay. The persistence of nonculturable NV was determined by RT-PCR assay only. Over 4 weeks, HAV survived exposure to acid marinade at pH 3.75. There was a 1.7-log reduction in HAV TCID50 titer but no reduction in NV or HAV RT-PCR titer after 4 weeks in marinated mussels. FCV was inactivated in acid conditions although it was still detectable by RT-PCR. To simulate preharvest virus contamination and commercial marination processing, experiments using fresh mussels infected with HAV and NV were performed. HAV and NV persistence was determined using semiquantitative real-time RT-PCR, and HAV infectivity was determined by the TCID50 assay. HAV retained infectivity following simulated commercial marination and exposure to acid conditions over 4 weeks. The survival of pathogenic enteric viruses in marinated mussels constitutes a potential health risk and so is of concern to public health authorities.
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