Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Implementation of PROMETHEUS 4‐step approach for evidence use in EFSA scientific assessments: benefits, issues, needs and solutions
    Aiassa, Elisa ; Martino, Laura ; Barizzone, Fulvio ; Ciccolallo, Laura ; Garcia, Ana ; Georgiadis, Marios ; Guajardo, Irene Muñoz ; Tomcikova, Daniela ; Alexander, Jan ; Calistri, Paolo ; Gundert‐remy, Ursula ; Hart, Andrew David ; Hoogenboom, Ron Laurentius ; Messean, Antoine ; Naska, Androniki ; Navarro, Maria Navajas ; Noerrung, Birgit ; Ockleford, Colin ; Wallace, Robert John ; Younes, Maged ; Abuntori, Blaize ; Alvarez, Fernando ; Aryeetey, Monica ; Baldinelli, Francesca ; Barrucci, Federica ; Bau, Andrea ; Binaglia, Marco ; Broglia, Alessandro ; Castoldi, Anna Federica ; Christoph, Eugen ; Sesmaisons‐Lecarré, Agnes De; Georgiadis, Nikolaos ; Gervelmeyer, Andrea ; Istace, Frederique ; López‐Gálvez, Gloria ; Manini, Paola ; Maurici, Daniela ; Merten, Caroline ; Messens, Winy ; Mosbach‐Schulz, Olaf ; Putzu, Claudio ; Bordajandi, Luisa Ramos ; Smeraldi, Camilla ; Tiramani, Manuela ; Martínez, Silvia Valtueña ; Sybren, Vos ; Hardy, Anthony Richard ; Hugas, Marta ; Kleiner, Juliane ; Seze, Guilhem De - \ 2018
    EFSA Supporting Publications 15 (2018)4. - ISSN 2397-8325
    In 2014, the European Food Safety Authority (EFSA) started the PROMETHEUS (PROmoting METHods for Evidence Use in Scientific assessments) project to improve further and increase the consistency of the methods it uses in its scientific assessments. The project defined a set of principles for the scientific assessment process and a 4‐step approach (plan/carry out/verify/report) for their fulfilment, which was tested in ten case studies, one from each EFSA panel. The present report describes the benefits, issues, needs and solutions related to the implementation of the 4‐step approach in EFSA, identified in a dedicated workshop in October 2017. The key benefits of the approach, which was deemed applicable to all types of EFSA scientific assessment including assessments of regulated products, are: 1) increased ‘scientific value’ of EFSA outputs, i.e. the extent of impartiality, methodological rigour, transparency and engagement; 2) guarantee of fitness‐for‐purpose, as it implies tailoring the methods to the specificities of each assessment; 3) efficiency gain, since preparing a protocol for the assessment upfront helps more streamlined processes throughout the implementation phase; 4) innovation, as the approach promotes the pioneering practice of ‘planning before doing’ (well established in primary research) for broad scientific assessments in regulatory science; and 5) increased harmonisation and consistency of EFSA assessments. The 4‐step approach was also considered an effective system for detecting additional methodological and/or expertise needs and a useful basis for further defining a quality management system for EFSA's scientific processes. The identified issues and solutions related to the implementation of the approach are: a) lack of engagement and need for effective communication on benefits and added value; b) need for further advances especially in the field of problem formulation/protocol development, evidence appraisal and evidence integration; c) need for specialised expertise in the previous aspects; and specific needs for d) assessments of regulated products and e) outsourced projects.
    DTREEv2, a computer-based support system for the risk assessment of genetically modified plants
    Pertry, I. ; Nothegger, C. ; Sweet, J. ; Kuiper, H.A. ; Davies, H. ; Iserentant, D. ; Hull, R. ; Mezzetti, B. ; Messens, K. ; Loose, M. De; Oliveira, D. de; Burssens, S. ; Gheysen, G. ; Tzotzos, G. - \ 2014
    New Biotechnology 31 (2014)2. - ISSN 1871-6784 - p. 166 - 171.
    Risk assessment of genetically modified organisms (GMOs) remains a contentious area and a major factor influencing the adoption of agricultural biotech. Methodologically, in many countries, risk assessment is conducted by expert committees with little or no recourse to databases and expert systems that can facilitate the risk assessment process. In this paper we describe DTREEv2, a computer-based decision support system for the identification of hazards related to the introduction of GM-crops into the environment. DTREEv2 structures hazard identification and evaluation by means of an Event-Tree type of analysis. The system produces an output flagging identified hazards and potential risks. It is intended to be used for the preparation and evaluation of biosafety dossiers and, as such, its usefulness extends to researchers, risk assessors and regulators in government and industry.
    Rodents are a risk factor for the spreading of pathogens on farms
    Meerburg, B.G. - \ 2010
    Veterinary Microbiology 142 (2010)3-4. - ISSN 0378-1135 - p. 464 - 465.
    campylobacter-jejuni - salmonella - transmission - colonization - pigs - mice
    In a recent paper Messens et al. (2009) investigate the genetic diversity of thermotolerant Campylobacter in commercial broiler flocks and in the environment of broiler farms in Belgium. One of their conclusions is that although rodents can serve as vectors and reservoirs of Campylobacter (Meerburg et al., 2006) these animals only impose a limited risk for introducing Campylobacter in broiler houses. This conclusion is based on the frequent presence of on-farm rodent control programs as previously described (Berndtson et al., 1996). Unfortunately, I cannot agree with Messens et al. on this point. Farmers generally apply rodent control programs to prevent economic losses, as rodents can cause considerable feed losses or structural damage (e.g. gnawing on insulation). However, farmers only do so when rodent densities exceed a certain subjective threshold (Meerburg and Kijlstra, 2007). In Denmark, it was found that mice were regularly observed on 69% of the farms but that their presence was rarely considered a problem by the farmers: only 9% thought it to be problematic (Leirs et al., 2004). This subjectivity means that farmers will act at different absolute numbers of rodents on their premises. The question remains at what absolute number rodent presence becomes a risk factor, but unfortunately exact quantification of this risk is extremely difficult (Berends et al., 1996). Potential contamination of livestock with pathogens of rodents is not yet seen as a problem by farmers. Furthermore, although many farmers claim to apply rodent control programs, these are often poorly operated, mostly due to lack of time. This attitude imposes a potential risk factor for the introduction of a number of different pathogens within livestock production and may cause food safety problems later in the chain. In case of Campylobacter, it was demonstrated that mice are able to carry this pathogen for a prolonged time and can act as reservoirs on the farm (Berndtson et al., 1994). Moreover, the presence of rats on farms has been associated with an increased risk of Campylobacter introduction into broiler houses (Kapperud et al., 1993), a conclusion shared by others (Kasrazadeh and Genigeorgis, 1987) who found that 87% of rat fecal samples tested were positive for C. jejuni. In the study of Berndtson et al. (1996) which is also mentioned by Messens and colleagues, it was shown that in flocks where mice were noticed, the Campylobacter frequency was 40% compared with 23% positive flocks were no mice were proven, although an estimation of the real number of mice was difficult in this study. Additionally, rodents were also identified as potential contamination source for other pathogens, such as Salmonella (Henzler and Opitz, 1992 D.J. Henzler and H.M. Opitz, The role of mice in the epizootiology of Salmonella enteritidis infection on chicken layer farms, Avian Dis. 36 (1992), pp. 625–631. View Record in Scopus | Cited By in Scopus (90)Henzler and Opitz, 1992) and more recently the protozoan parasite Toxoplasma gondii (Kijlstra et al., 2008). Thus, the conclusion that rodent presence can be considered a limited risk factor seems incorrect. Instead, the importance of proper on-farm rodent management for food safety purposes should be stressed in order to minimize this potential risk factor. Rodent management consists of a combination of three elements: prevention, monitoring and control. Good understanding of ecology of the pest species should be the main focus. Farmers should be advised that it is not only important to apply rodent management to prevent economic losses but also from a veterinary perspective. This is important, as agriculture in general is changing to more open production systems due to public demands (as is the case with organic farming), which may result in more interaction between livestock and wild fauna.
    Bacteriological contamination, dirt, and cracks of eggshells in furnished cages and noncage systems for laying hens: An international on-farm comparison
    Reu, K. de; Rodenburg, T.B. ; Messens, W. ; Heyndrickx, M. ; Tuyttens, F. ; Sonck, B. ; Zoons, J. ; Herman, L. - \ 2009
    Poultry Science 88 (2009)11. - ISSN 0032-5791 - p. 2442 - 2448.
    housing systems - conventional cages - egg quality - health - performance - design - hybrid - layers - flora
    For laying hens, the effects of housing system on bacterial eggshell contamination and eggshell quality is almost exclusively studied in experimental hen houses. The aim of this study was to compare eggshell hygiene and quality under commercial conditions. Six flocks of laying hens in furnished cages and 7 flocks in noncage systems were visited when hens were about 60 wk of age. Farms from Belgium, the Netherlands, and Germany were included in the study. The following parameters were determined on eggs sampled at the egg belts: 1) bacterial eggshell contamination, as expressed by total count of aerobic bacteria and number of Enterobacteriaceae; 2) proportion of dirty eggs; and 3) proportion of cracked eggs and eggs with microcracks. Considerable within-flock differences were found in eggshell contamination with total count of aerobic bacteria, both for furnished cages (P 0.001, range 4.24 to 5.22 log cfu/eggshell) and noncage systems (P 0.001, range 4.35 to 5.51 log cfu/eggshell). On average, lower levels of contamination with total count of aerobic bacteria (4.75 vs. 4.98 log cfu/eggshell; P 0.001) were found on eggshells from furnished cages compared with noncage systems. Concerning Enterobacteriaceae, no significant difference in average eggshell contamination between both systems could be shown. The total percentage of cracked eggs was higher (P 0.01) in furnished cages (7.8%) compared with noncage systems (4.1%). This was, however, due to the high percentage of cracked eggs (24%) observed on one of the furnished cage farms. We conclude that bacteriological eggshell contamination and percentage of cracked eggs differed substantially between individual farms using the same housing system. This may also explain some discrepancies between the findings of the present study versus some findings of previous experimental studies or studies on a small number of farms. Although statistically significant, the average differences in bacteriological contamination of nest eggs between both housing systems have limited microbiological relevancy
    Bacterial contamination of table eggs and the influence of housing systems
    Reu, K. de; Messens, W. ; Heyndrickx, M. ; Rodenburg, T.B. ; Uyttendaele, M. ; Herman, L. - \ 2008
    Worlds Poultry Science Journal 64 (2008). - ISSN 0043-9339 - p. 5 - 19.
    enterica serovar enteritidis - surface microbial-populations - experimentally infected hens - salmonella-enteritidis - laying hens - furnished cages - phage type-4 - yersinia-enterocolitica - production performance - conventional cages
    With the introduction of alternative housing systems for laying hens in the EU, recent research has focussed on the bacterial contamination of table eggs, e.g. eggshell and egg content contamination. Contamination of eggshells with aerobic bacteria is generally higher for nest eggs from non-cage systems compared to nest eggs from furnished cages or eggs from conventional cages. Studies indicate limited or no systematic differences in eggshell contamination with aerobic bacteria between eggs laid in the nest boxes of furnished cages and eggs laid in conventional cages. The major differences found in experimental studies between cage- and non-cage systems are less pronounced under commercial conditions. The effect of housing system on eggshell contamination with specific groups of bacteria is variable. Limited information is available on the influence of housing system on egg content contamination. Recent research does not indicate large differences in egg content contamination between eggs from cage- and non-cage systems (ignoring outside nest and floor eggs). The microflora of the eggshell is dominated by Gram-positive bacteria, whereas Gram-negative bacteria are best equipped to overcome the antimicrobial defences of the egg content. Much of the research on eggshell and egg content contamination focuses on Salmonella, since infection with Salmonella enteritidis, resulting from the consumption of contaminated eggs or egg products, is still a major health problem. Observed Salmonella prevalence on the eggshell and in the egg content vary, depending on the fact whether investigations were based on randomly sampled table eggs or on eggs from naturally infected hens. The limited information available on other pathogens shows that they are exclusively isolated from the eggshell and not from the internal contents.
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