Temperature is considered as the major factor determining virus inactivation in the environment. Food industries, therefore, widely apply temperature as virus inactivating parameter. This review ...encompasses an overview of viral inactivation and virus genome degradation data from published literature as well as a statistical analysis and the development of empirical formulae to predict virus inactivation. A total of 658 data (time to obtain a first log10 reduction) were collected from 76 published studies with 563 data on virus infectivity and 95 data on genome degradation. Linear model fitting was applied to analyse the effects of temperature, virus species, detection method (cell culture or molecular methods), matrix (simple or complex) and temperature category (<50 and ≥50°C). As expected, virus inactivation was found to be faster at temperatures ≥50°C than at temperatures <50°C, but there was also a significant temperature–matrix effect. Virus inactivation appeared to occur faster in complex than in simple matrices. In general, bacteriophages PRD1 and PhiX174 appeared to be highly persistent whatever the matrix or the temperature, which makes them useful indicators for virus inactivation studies. The virus genome was shown to be more resistant than infectious virus. Simple empirical formulas were developed that can be used to predict virus inactivation and genome degradation for untested temperatures, time points or even virus strains.
To establish a possible role for the natural environment in the transmission of clinically relevant AMR bacteria to humans, a literature review was conducted to systematically collect and categorize ...evidence for human exposure to extended-spectrum β-lactamase-producing Enterobacteriaceae, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus spp. in the environment. In total, 239 datasets adhered to inclusion criteria. AMR bacteria were detected at exposure-relevant sites (35/38), including recreational areas, drinking water, ambient air, and shellfish, and in fresh produce (8/16). More datasets were available for environmental compartments (139/157), including wildlife, water, soil, and air/dust. Quantitative data from exposure-relevant sites (6/35) and environmental compartments (11/139) were scarce. AMR bacteria were detected in the contamination sources (66/66) wastewater and manure, and molecular data supporting their transmission from wastewater to the environment (1/66) were found. The abundance of AMR bacteria at exposure-relevant sites suggests risk for human exposure. Of publications pertaining to both environmental and human isolates, however, only one compared isolates from samples that had a clear spatial and temporal relationship, and no direct evidence was found for transmission to humans through the environment. To what extent the environment, compared to the clinical and veterinary domains, contributes to human exposure needs to be quantified. AMR bacteria in the environment, including sites relevant for human exposure, originate from contamination sources. Intervention strategies targeted at these sources could therefore limit emission of AMR bacteria to the environment.
The quality of drinking water in the Netherlands has to comply with the Dutch Drinking Water Directive: less than one infection in 10,000 persons per year may occur due to consumption of unboiled ...drinking water. Since virus concentrations in drinking waters may be below the detection limit but entail a public health risk, the infection risk from drinking water consumption requires the assessment of the virus concentrations in source waters and of the removal efficiency of treatment processes. In this study, samples of source waters were taken during 4 years of regular sampling (1999 to 2002), and enteroviruses, reoviruses, somatic phages, and F-specific phages were detected in 75% (range, 0.0033 to 5.2 PFU/liter), 83% (0.0030 to 5.9 PFU/liter), 100% (1.1 to 114,156 PFU/liter), and 97% (0.12 to 14,403 PFU/liter), respectively, of 75 tested source water samples originating from 10 locations for drinking water production. By endpoint dilution reverse transcription-PCR (RT-PCR), 45% of the tested source water samples were positive for norovirus RNA (0.22 to 177 PCR-detectable units PDU/liter), and 48% were positive for rotavirus RNA (0.65 to 2,249 PDU/liter). Multiple viruses were regularly detected in the source water samples. A significant correlation between the concentrations of the two phages and those of the enteroviruses could be demonstrated. The virus concentrations varied greatly between 10 tested locations, and a seasonal effect was observed. Peak concentrations of pathogenic viruses occur in source waters used for drinking water production. If seasonal and short-term fluctuations coincide with less efficient or failing treatment, an unacceptable public health risk from exposure to this drinking water may occur.
In this work, a new approach towards virus reduction is taken, where modified membranes with large pore sizes (>450 nm) can reach high log10-unit virus reductions. Polyelectrolyte coatings were used ...to modify microfiltration (MF) membranes to impart antiviral properties. A stable covalent layer-by-layer (LBL) approach was used to create multilayers from a single polyelectrolyte, polyethyleneimine (PEI). Here terephthalaldehyde (TA) crosslinking was used to create crosslinked multilayers, both on model surfaces and on commercial polyether sulfone, (PES) MF membranes. The substrates were further coated with antiviral silver, and copper nanoparticles (Ag and CuNPs) stabilised with PEI. The specific fabrication during the LBL assembly was stepwise characterised using multi-surface analysis including Fourier transform infrared spectroscopy (FTIR), Atomic Force Microscope (AFM), ellipsometry, zeta potential and contact angle measurements. Model surfaces demonstrated a 4 log10-units reduction of MS2 viral titre, independent of the crosslinked PEI layer thickness. The crosslinked PEI and Ag/CuNPs-modified membranes efficiently reduced 4.5–5 log10-units of infectious MS2 bacteriophages by both adsorption and inactivation of viral particles. This was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR), which showed a stable performance over time. Pure water flux measurements on modified-membranes showed good long-term stability. Thus, 5000 L/m2 of virus-free water was produced in approximately 2 h, using gravity-based filtration. Furthermore, there was no observable leaching of nanoparticles from the membranes during filtration.
Display omitted
•Crosslinked PEI layers on model surfaces lead to significant 4 log10 MS2 reductions.•These layers were successfully applied to MF membranes, with only a small decrease in permeability.•The coatings were found to be stable and performed well under gravity filtration.•Coated MF membranes showed a >3 log10 MS2 reduction.•Coated MF membranes optimised with Cu and Ag NPs showed >5 log10 MS2 reductions.
Flooding and heavy rainfall have been associated with waterborne infectious disease outbreaks, however, it is unclear to which extent they pose a risk for public health. Here, risks of infection from ...exposure to urban floodwater were assessed using quantitative microbial risk assessment (QMRA). To that aim, urban floodwaters were sampled in the Netherlands during 23 events in 2011 and 2012. The water contained Campylobacter jejuni (prevalence 61%, range 14- >103 MPN/l), Giardia spp. (35%, 0.1–142 cysts/l), Cryptosporidium (30%, 0.1–9.8 oocysts/l), noroviruses (29%, 102–104 pdu/l) and enteroviruses (35%, 103–104 pdu/l). Exposure data collected by questionnaire, revealed that children swallowed 1.7 ml (mean, 95% Confidence Interval 0–4.6 ml) per exposure event and adults swallowed 0.016 ml (mean, 95% CI 0–0.068 ml) due to hand-mouth contact. The mean risk of infection per event for children, who were exposed to floodwater originating from combined sewers, storm sewers and rainfall generated surface runoff was 33%, 23% and 3.5%, respectively, and for adults it was 3.9%, 0.58% and 0.039%. The annual risk of infection was calculated to compare flooding from different urban drainage systems. An exposure frequency of once every 10 years to flooding originating from combined sewers resulted in an annual risk of infection of 8%, which was equal to the risk of infection of flooding originating from rainfall generated surface runoff 2.3 times per year. However, these annual infection risks will increase with a higher frequency of urban flooding due to heavy rainfall as foreseen in climate change projections.
•Urban flooding was measured for enteric pathogens to assess risks for public health.•Health risks were quantified for flooding of different urban drainage systems.•The annual risk of infection for flooding originating from combined sewers was 8%.
The water in the canals and some recreational lakes in Amsterdam is microbiologically contaminated through the discharge of raw sewage from houseboats, sewage effluent, and dog and bird feces. ...Exposure to these waters may have negative health effects. During two successive 1-year study periods, the water quality in two canals (2003 to 2004) and five recreational lakes (2004 to 2005) in Amsterdam was tested with regard to the presence of fecal indicators and waterborne pathogens. According to Bathing Water Directive 2006/7/EC, based on Escherichia coli and intestinal enterococcus counts, water quality in the canals was poor but was classified as excellent in the recreational lakes. Campylobacter, Salmonella, Cryptosporidium, and Giardia were detected in the canals, as was rotavirus, norovirus, and enterovirus RNA. Low numbers of Cryptosporidium oocysts and Giardia cysts were detected in the recreational lakes, despite compliance with European bathing water legislation. The estimated risk of infection with Cryptosporidium and Giardia per exposure event ranged from 0.0002 to 0.007% and 0.04 to 0.2%, respectively, for occupational divers professionally exposed to canal water. The estimated risk of infection at exposure to incidental peak concentrations of Cryptosporidium and Giardia may be up to 0.01% and 1%, respectively, for people who accidentally swallow larger volumes of the canal water than the divers. Low levels of viable waterborne pathogens, such as Cryptosporidium and Giardia, pose a possible health risk from occupational, accidental, and recreational exposure to surface waters in Amsterdam.
To date, sources of hepatitis E virus (HEV) in the Netherlands, including swine and wild boar, have been identified, but no direct attribution to Dutch hepatitis E cases have been demonstrated. Other ...animal sources may exist. To identify these species, HEV RNA detection by RT-PCR is required, but complicated. A preselection based on serology may be useful. Therefore, wildlife species were studied by serology and molecular methods. Using a species-independent double-antigen sandwich ELISA, HEV-specific antibodies were detected in sera from 12% of 1029 wild boar (
Sus scrofa scrofa), in 5% of 38 red deer (
Cervus elaphus) and in none of 8 studied roe deer (
Capreolus capreolus). Differences in background signals were observed between species and accounted for by fitting finite mixture distributions. HEV RNA was detected in 8% of 106 wild boars, in 15% of 39 red deer and in none of 8 roe deer. In conclusion, HEV was shown to be present in European red deer for the first time. This preselection based on species-independent serological assays may be beneficial to identify new potential animal reservoirs of HEV. The consumption of Dutch undercooked wild boar and red deer meat may lead to human exposure to HEV.
Since the transmission of pathogenic viruses via water is indistinguishable from the transmission via other routes and since the levels in drinking water, although significant for health, may be too ...low for detection, quantitative viral risk assessment is a useful tool for assessing disease risk due to consumption of drinking water. Quantitative viral risk assessment requires information concerning the ability of viruses detected in drinking water to infect their host. To obtain insight into the infectivity of viruses in relation to the presence of virus genomes, inactivation of three different enteroviruses in artificial ground and surface waters under different controlled pH, temperature, and salt conditions was studied by using both PCR and cell culture over time. In salt-peptone medium, the estimated ratio of RNA genomes to infectious poliovirus 1 in freshly prepared suspensions was about 10⁰. At 4°C this ratio was 10³ after 600 days, and at 22°C it was 10⁴ after 200 days. For poliovirus 1 and 2 the RNA/infectious virus ratio was higher in artificial groundwater than in artificial surface water, but this was not the case for coxsackievirus B4. When molecular detection is used for virus enumeration, it is important that the fraction of infectious virus (based on all virus genomes detected) decays with time, especially at temperatures near 22°C.
PDF
