• QMRA of adenovirus in drinking water at a drinking water treatment plant using UV and chlorine dioxide disinfection.

      Schijven, Jack; Teunis, Peter; Suylen, Trudy; Ketelaars, Henk; Hornstra, Luc; Rutjes, Saskia (2019-07-01)
      According to the Dutch Drinking Water Act of 2011, Dutch drinking water suppliers must conduct a Quantitative Microbial Risk Assessment (QMRA) for infection by the following index pathogens: enterovirus, Campylobacter, Cryptosporidium and Giardia at least once every four years in order to assess the microbial safety of drinking water. The health-based target for safe drinking water is set at less than one infection per 10 000 persons per year. At Evides Water Company, concern has arisen whether their drinking water treatment, mainly based on UV inactivation and chlorine dioxide, reduces levels of adenovirus (AdV) sufficiently. The main objective was, therefore, to conduct a QMRA for AdV. Estimates of the AdV concentrations in source water were based on enumeration of total AdV by integrated cell culture PCR (iccPCR), most probable number PCR (mpnPCR) and quantitative PCR (qPCR), and on enumeration of AdV40/41 by mpnPCR and qPCR. AdV40/41 represents a large fraction of total AdV and only a small fraction of AdV is infectious (1/1700). By comparison of literature data and plant scale data, somatic coliphages appeared a good, conservative indicator for AdV disinfection by UV irradiation. Similarly, bacteriophage MS2 appeared to be a good, conservative indicator for disinfection by chlorine dioxide. Literature data on the efficiency of chlorine dioxide disinfection were fitted with the extended HOM model. Chlorine dioxide disinfection at low initial concentrations (0.05-0.1 mg/l) was found to be the major treatment step, providing sufficient treatment on its own for compliance with the health-based target. UV disinfection of AdV at 40 mJ/cm2 or 73 mJ/cm2 was insufficient without chlorine dioxide disinfection.
    • QSAR-based estimation of SSD parameters - an exploratory investigation.

      Hoondert, Renske; Oldenkamp, Rik; de Zwart, Dick; van de Meent, Dik; Posthuma, Leo (2019-09-25)
      Ecological risk assessments are hampered by limited availability of ecotoxicity data. The present study aimed to explore the possibility of deriving SSD (species sensitivity distribution) parameters for non-tested compounds, based on simple physicochemical characteristics, known SSDs for data-rich compounds and a QSAR-type approach. The median toxicity of a data-poor chemical for species assemblages significantly varies with values of the physicochemical descriptors, especially when based on high quality SSD data (either from acute EC50 s or chronic NOECs). Beyond exploratory uses, we discussed how the precision of QSAR-based SSDs can be improved to construct models that accurately predict the SSD-parameters of data poor chemicals. The current models show that the concept of QSAR-based SSDs supports screening-level evaluations of the potential ecotoxicity of compounds for which data are lacking. This article is protected by copyright. All rights reserved.
    • Qualitative Evaluation of the STOEMP Network in Ghent: An Intersectoral Approach to Make Healthy and Sustainable Food Available to All.

      Vos, Marjolijn; Romeo-Velilla, Maria; Stegeman, Ingrid; Bell, Ruth; Vliet, Nina van der; Lippevelde, Wendy Van (2020-04-28)
    • Qualitative modelling of social determinants of health using group model building: the case of debt, poverty, and health.

      Reumers, Laurens; Bekker, Marleen; Hilderink, Henk; Jansen, Maria; Helderman, Jan-Kees; Ruwaard, Dirk (2022-05-19)
    • Qualitative Research: Institutional Preparedness During Threats of Infectious Disease Outbreaks.

      de Rooij, Doret; Belfroid, Evelien; Eilers, Renske; Roßkamp, Dorothee; Swaan, Corien; Timen, Aura (2020-01-01)
      A qualitative three-step study among infectious disease prevention and control experts was performed. First, interviews (n = 5) were conducted to identify which factors trigger preparedness activities during an unfolding threat. Second, these triggers informed the design of a phased preparedness system which was tested in a focus group discussion (n = 5) were conducted to identify which factors trigger preparedness activities during an unfolding threat. Second, these triggers informed the design of a phased preparedness system which was tested in a focus group discussion (n = 5) were conducted to identify which factors trigger preparedness activities during an unfolding threat. Second, these triggers informed the design of a phased preparedness system which was tested in a focus group discussion (.
    • A qualitative study of parental associations and beliefs regarding the HPV vaccination for Dutch boys.

      Venderbos, Judith R; Eilers, Renske; de Vries, Hein; van Zoonen, Kim (2022-06-14)
    • "": A Qualitative Study of the Support Needs of Working Caregivers Taking Care of Older Adults.

      Vos, Eline E; De Bruin, Simone R; van der Beek, Allard J; Proper, Karin I (2021-05-26)
    • Quality assurance of colonoscopy within the Dutch national colorectal cancer screening program.

      Bronzwaer, Maxime E S; Depla, Annekatrien C T M; van Lelyveld, Niels; Spanier, Marcel B W; Oosterhout, Yvonne H; van Leerdam, Monique E; Spaander, Manon C W; Dekker, Evelien; van Haastert, M; Keller, J J; et al. (2018-09-18)
      Colorectal cancer (CRC) screening is capable of reducing CRC-related morbidity and mortality. Colonoscopy is the reference standard to detect CRC, also providing the opportunity to detect and resect its precursor lesions; colorectal polyps. Therefore, colonoscopy is either used as a primary screening tool or as a subsequent procedure after a positive triage test in screening programs based on non-invasive stool testing or sigmoidoscopy. However, in both settings, colonoscopy is not fully protective for the occurrence of post-colonoscopy CRCs (PCCRCs). Because the majority of PCCRCs are the result of colonoscopy-related factors, a high-quality procedure is of paramount importance to assure optimal effectiveness of CRC screening programs. For this reason, at the start of the Dutch fecal immunochemical test (FIT)-based screening program, quality criteria for endoscopists performing colonoscopies in FIT-positive screenees, as well as for endoscopy centers, were defined. In conjunction, an accreditation and auditing system was designed and implemented. In this report we describe the quality assurance process for endoscopists participating in the Dutch national CRC Screening Program, including a detailed description of the evidence-based quality criteria. We believe that our experience might serve as an example for colonoscopy quality assurance programs in other CRC screening programs.
    • Quality evaluation of human and environmental toxicity studies performed with nanomaterials – the GUIDEnano approach

      Fernández-Cruz, M. L.; Hernández-Moreno, D.; Catalán, J.; Cross, R. K.; Stockmann-Juvala, H.; Cabellos, J.; Lopes, Viviana R.; Matzke, M.; Ferraz, N.; Izquierdo, J. J.; et al. (2018)
      The GUIDEnano quality tool establishes objective criteria to score the quality of eco/toxicity studies performed with nanomaterials.
    • Quantification of Salmonella Survival and Infection in an In vitro Model of the Human Intestinal Tract as Proxy for Foodborne Pathogens.

      Wijnands, Lucas M; Teunis, Peter F M; Kuijpers, Angelina F A; Delfgou-Van Asch, Ellen H M; Pielaat, Annemarie (2017)
      Different techniques are available for assessing differences in virulence of bacterial foodborne pathogens. The use of animal models or human volunteers is not expedient for various reasons; the use of epidemiological data is often hampered by lack of crucial data. In this paper, we describe a static, sequential gastrointestinal tract (GIT) model system in which foodborne pathogens are exposed to simulated gastric and intestinal contents of the human digestive tract, including the interaction of pathogens with the intestinal epithelium. The system can be employed with any foodborne bacterial pathogens. Five strains of Salmonella Heidelberg and one strain of Salmonella Typhimurium were used to assess the robustness of the system. Four S. Heidelberg strains originated from an outbreak, the fifth S. Heidelberg strain and the S. Typhimurium strain originated from routine meat inspections. Data from plate counts, collected for determining the numbers of surviving bacteria in each stage, were used to quantify both the experimental uncertainty and biological variability of pathogen survival throughout the system. For this, a hierarchical Bayesian framework using Markov chain Monte Carlo (MCMC) was employed. The model system is able to distinguish serovars/strains for in vitro infectivity when accounting for within strain biological variability and experimental uncertainty.
    • Quantification of T-cell dynamics during latent cytomegalovirus infection in humans.

      van den Berg, Sara P H; Derksen, Lyanne Y; Drylewicz, Julia; Nanlohy, Nening M; Beckers, Lisa; Lanfermeijer, Josien; Gessel, Stephanie N; Vos, Martijn; Otto, Sigrid A; de Boer, Rob J; et al. (2021-12-16)
    • Quantifying antibiotic impact on within-patient dynamics of extended-spectrum beta-lactamase resistance.

      Niehus, Rene; van Kleef, Esther; Mo, Yin; Turlej-Rogacka, Agata; Lammens, Christine; Carmeli, Yehuda; Goossens, Herman; Tacconelli, Evelina; Carevic, Biljana; Preotescu, Liliana; et al. (2020-05-07)
      Antibiotic-induced perturbation of the human gut flora is expected to play an important role in mediating the relationship between antibiotic use and the population prevalence of antibiotic resistance in bacteria, but little is known about how antibiotics affect within-host resistance dynamics. Here we develop a data-driven model of the within-host dynamics of extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae. We use blaCTX-M (the most widespread ESBL gene family) and 16S rRNA (a proxy for bacterial load) abundance data from 833 rectal swabs from 133 ESBL-positive patients followed up in a prospective cohort study in three European hospitals. We find that cefuroxime and ceftriaxone are associated with increased blaCTX-M abundance during treatment (21% and 10% daily increase, respectively), while treatment with meropenem, piperacillin-tazobactam, and oral ciprofloxacin is associated with decreased blaCTX-M (8% daily decrease for all). The model predicts that typical antibiotic exposures can have substantial long-term effects on blaCTX-M carriage duration.
    • Quantifying biomass production for assessing ecosystem services of riverine landscapes

      Koopman, K.R.; Straatsma, M.W.; Augustijn, D.C.M.; Breure, A.M.; Lenders, H.J.R.; Stax, S.J.; Leuven, R.S.E.W. (2018-05)
    • Quantifying contributions of chlorofluorocarbon banks to emissions and impacts on the ozone layer and climate.

      Lickley, Megan; Solomon, Susan; Fletcher, Sarah; Velders, Guus J M; Daniel, John; Rigby, Matthew; Montzka, Stephen A; Kuijpers, Lambert J M; Stone, Kane (2020-03-17)
      Chlorofluorocarbon (CFC) banks from uses such as air conditioners or foams can be emitted after global production stops. Recent reports of unexpected emissions of CFC-11 raise the need to better quantify releases from these banks, and associated impacts on ozone depletion and climate change. Here we develop a Bayesian probabilistic model for CFC-11, 12, and 113 banks and their emissions, incorporating the broadest range of constraints to date. We find that bank sizes of CFC-11 and CFC-12 are larger than recent international scientific assessments suggested, and can account for much of current estimated CFC-11 and 12 emissions (with the exception of increased CFC-11 emissions after 2012). Left unrecovered, these CFC banks could delay Antarctic ozone hole recovery by about six years and contribute 9 billion metric tonnes of equivalent CO2 emission. Derived CFC-113 emissions are subject to uncertainty, but are much larger than expected, raising questions about its sources.
    • Quantifying heterogeneity in sexual behaviour and distribution of STIs before and after pre-exposure prophylaxis among men who have sex with men.

      van Wees, Daphne Amanda; Diexer, Sophie; Rozhnova, Ganna; Matser, Amy; den Daas, Chantal; Heijne, Janneke; Kretzschmar, Mirjam (2021-10-29)
      Objectives: Pre-exposure prophylaxis (PrEP) use may influence sexual behaviour and transmission of STIs among men who have sex with men (MSM). We aimed to quantify the distribution of STI diagnoses among MSM in the Netherlands based on their sexual behaviour before and after the introduction of PrEP.Methods: HIV-negative MSM participating in a prospective cohort study (Amsterdam Cohort Studies) completed questionnaires about sexual behaviour and were tested for STI/HIV during biannual visits (2009-2019). We developed a sexual behaviour risk score predictive of STI diagnosis and used it to calculate Gini coefficients for gonorrhoea, chlamydia and syphilis diagnoses in the period before (2009 to mid-2015) and after PrEP (mid-2015 to 2019). Gini coefficients close to zero indicate that STI diagnoses are homogeneously distributed over the population, and close to one indicate that STI diagnoses are concentrated in individuals with a higher risk score.Results: The sexual behaviour risk score (n=630, n visits=10 677) ranged between 0.00 (low risk) and 3.61 (high risk), and the mean risk score increased from 0.70 (SD=0.66) before to 0.93 (SD=0.80) after PrEP. Positivity rates for chlamydia (4%) and syphilis (1%) remained relatively stable, but the positivity rate for gonorrhoea increased from 4% before to 6% after PrEP. Gini coefficients increased from 0.37 (95% CI 0.30 to 0.43) to 0.43 (95% CI 0.36 to 0.49) for chlamydia, and from 0.37 (95% CI 0.19 to 0.52) to 0.50 (95% CI 0.32 to 0.66) for syphilis comparing before to after PrEP. The Gini coefficient for gonorrhoea remained stable at 0.46 (95% CI 0.40 to 0.52) before and after PrEP.Conclusions: MSM engaged in more high-risk sexual behaviour and gonorrhoea diagnoses increased after PrEP was introduced. Chlamydia and syphilis diagnoses have become more concentrated in a high-risk subgroup. Monitoring the impact of increasing PrEP coverage on sexual behaviour and STI incidence is important. Improved STI prevention is needed, especially for high-risk MSM.
    • Quantifying the impact of mass vaccination programmes on notified cases in the Netherlands.

      van Wijhe, M; Tulen, A D; Korthals Altes, H; McDonald, S A; de Melker, H E; Postma, M J; Wallinga, J (2018-03-14)
      Vaccination programmes are considered a main contributor to the decline of infectious diseases over the 20th century. In recent years, the national vaccination coverage in the Netherlands has been declining, highlighting the need for continuous monitoring and evaluation of vaccination programmes. Our aim was to quantify the impact of long-standing vaccination programmes on notified cases in the Netherlands. We collected and digitised previously unavailable monthly case notifications of diphtheria, poliomyelitis, mumps and rubella in the Netherlands over the period 1919-2015. Poisson regression models accounting for seasonality, multi-year cycles, secular trends and auto-correlation were fit to pre-vaccination periods. Cases averted were calculated as the difference between observed and expected cases based on model projections. In the first 13 years of mass vaccinations, case notifications declined rapidly with 82.4% (95% credible interval (CI): 74.9-87.6) of notified cases of diphtheria averted, 92.9% (95% CI 85.0-97.2) cases of poliomyelitis, and 79.1% (95% CI 67.1-87.4) cases of mumps. Vaccination of 11-year-old girls against rubella averted 49.9% (95% CI 9.3-73.5) of cases, while universal vaccination averted 68.1% (95% CI 19.4-87.3) of cases. These findings show that vaccination programmes have contributed substantially to the reduction of infectious diseases in the Netherlands.
    • Quantifying the impact of social groups and vaccination on inequalities in infectious diseases using a mathematical model.

      Munday, James D; van Hoek, Albert Jan; Edmunds, W John; Atkins, Katherine E (2018-09-26)
      Social and cultural disparities in infectious disease burden are caused by systematic differences between communities. Some differences have a direct and proportional impact on disease burden, such as health-seeking behaviour and severity of infection. Other differences-such as contact rates and susceptibility-affect the risk of transmission, where the impact on disease burden is indirect and remains unclear. Furthermore, the concomitant impact of vaccination on such inequalities is not well understood.
    • Quantifying the public's view on social value judgments in vaccine decision-making: A discrete choice experiment.

      Luyten, Jeroen; Kessels, Roselinde; Atkins, Katherine E; Jit, Mark; van Hoek, Albert Jan (2019-03-20)
      Vaccination programs generate direct protection, herd protection and, occasionally, side effects, distributed over different age groups. This study elicits the general public's view on how to balance these outcomes in funding decisions for vaccines. We performed an optimal design discrete choice experiment with partial profiles in a representative sample (N = 1499) of the population in the United Kingdom in November 2016. Using a panel mixed logit model, we quantified, for four different types of infectious disease, the importance of a person's age during disease, how disease was prevented-via direct vaccine protection or herd protection-and whether the vaccine induced side effects. Our study shows clear patterns in how the public values vaccination programs. These diverge from the assumptions made in public health and cost-effectiveness models that inform decision-making. We found that side effects and infections in newborns and children were of primary importance to the perceived value of a vaccination program. Averting side effects was, in any age group, weighted three times as important as preventing an identical natural infection in a child whereas the latter was weighted six times as important as preventing the same infection in elderly aged 65-75 years. These findings were independent of the length or severity of the disease, and were robust across respondents' backgrounds. We summarize these patterns in a set of preference weights that can be incorporated into future models. Although the normative significance of these weights remains a matter open for debate, our study can, hopefully, contribute to the evaluation of vaccination programs beyond cost-effectiveness.