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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    Risk factors for persistence of livestock-associated MRSA and environmental exposure in veal calf farmers and their family members: an observational longitudinal study
    Dorado-Garcia, A. ; Bos, M.E.H. ; Graveland, H. ; Cleef, B.A.G.L. van; Verstappen, K.M. ; Kluytmans, J.A.J.W. ; Wagenaar, J.A. ; Heederik, D.J.J. - \ 2013
    BMJ Open 3 (2013)9. - ISSN 2044-6055
    resistant staphylococcus-aureus - animals - carriage - origin - health - st398 - infections - emergence - france - calves
    Objectives: Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) emergence is a major public health concern. This study was aimed at assessing risk factors for persistently carrying MRSA in veal calf farmers and their family members. We also evaluate the dynamics of MRSA environmental load during the veal-calf production cycle. Design: Observational, longitudinal, repeated cross-sectional study. Setting: 52 veal calf farms in the Netherlands. Participants: From the end of 2010 to the end of 2011, a total of 211 farmers, family members and employees were included in the study. Primary outcome and secondary outcome measures: Nasal swabs were taken from participants on days 0, 4, 7 and week 12. A persistent MRSA carrier was defined as a person positive for MRSA on days 0, 4 and 7. Participants filled in an extensive questionnaire to identify potential risk factors and confounders. For estimation of MRSA prevalence in calves and environmental contamination, animal nasal swabs and Electrostatic Dust Collectors were taken on day 0 and week 12. Results: The presence of potential animal reservoirs (free-ranging farm cats and sheep) and the level of contact with veal calves was positively associated with persistent MRSA carriage. Interestingly, at the end of the study (week 12), there was a twofold rise in animal prevalence and a significantly higher MRSA environmental load in the stables was found on farms with MRSA carriers. Conclusions: This study supports the hypothesis that environmental contamination with MRSA plays a role in the acquisition of MRSA in farmers and their household members and suggests that other animal species should also be targeted to implement effective control strategies.
    Consumption of antimicrobials in pigs, veal calves, and broilers in the Netherlands: Quantitative results of nationwide collection of data in 2011
    Bos, M.E.H. ; Taverne, F.J. ; Geijlswijk, I.M. van; Mouton, J.W. ; Mevius, D.J. ; Heederik, D.J.J. - \ 2013
    PLoS ONE 8 (2013)10. - ISSN 1932-6203 - 9 p.
    resistant staphylococcus-aureus - escherichia-coli - animals - farmers - health - costs - herds - usage - meat - food
    In 2011, Dutch animal production sectors started recording veterinary antimicrobial consumption. These data are used by the Netherlands Veterinary Medicines Authority to create transparency in and define benchmark indicators for veterinary consumption of antimicrobials. This paper presents the results of sector wide consumption of antimicrobials, in the form of prescriptions or deliveries, for all pig, veal calf, and broiler farms. Data were used to calculate animal defined daily dosages per year (ADDD/Y) per pig or veal calf farm. For broiler farms, number of animal treatment days per year was calculated. Furthermore, data were used to calculate the consumption of specific antimicrobial classes per administration route per pig or veal calf farm. The distribution of antimicrobial consumption per farm varied greatly within and between farm categories. All categories, except for rosé starter farms, showed a highly right skewed distribution with a long tail. Median ADDD/Y values varied from 1.2 ADDD/Y for rosé finisher farms to 83.2 ADDD/Y for rosé starter farms, with 28.6 ADDD/Y for white veal calf farms. Median consumption in pig farms was 9.3 ADDD/Y for production pig farms and 3.0 ADDD/Y for slaughter pig farms. Median consumption in broiler farms was 20.9 ATD/Y. Regarding specific antimicrobial classes, fluoroquinolones were mainly used on veal calf farms, but in low quantities: P75 range was 0 – 0.99 ADDD/Y, and 0 – 0.04 ADDD/Y in pig farms. The P75 range for 3rd/4th-generation cephalosporins was 0 – 0.07 ADDD/Y for veal calf farms, and 0 – 0.1 ADDD/Y for pig farms. The insights obtained from these results, and the full transparency obtained by monitoring antimicrobial consumption per farm, will help reduce antimicrobial consumption and endorse antimicrobial stewardship. The wide and skewed distribution in consumption has important practical and methodological implications for benchmarking, surveillance and future analysis of trends.
    Within-farm dynamics of ESBL/AmpC-producing Escherichia coli in veal calves: a longitudinal approach
    Hordijk, J. ; Mevius, D.J. ; Kant, A. ; Bos, M.E.H. ; Graveland, H. ; Bosman, A.B. ; Hartskeerl, M. ; Heederik, D.J.J. ; Wagenaar, J.A. - \ 2013
    Journal of Antimicrobial Chemotherapy 68 (2013)11. - ISSN 0305-7453 - p. 2468 - 2476.
    spectrum-beta-lactamase - food-producing animals - plasmids encoding ctx-m-14 - extended-spectrum - klebsiella-pneumoniae - antimicrobial agents - companion animals - fecal carriage - young calves - resistance
    OBJECTIVES: To assess the within-farm dynamics of extended-spectrum ß-lactamase (ESBL)/AmpC-producing Escherichia coli in veal calves. METHODS: Three veal-calf fattening farms were screened. Faecal samples from all calves within a compartment (109-150 per farm) were taken upon arrival on the farm (T0) and after 3, 6, 8 and 10 weeks (T3-T10). ESBL/AmpC genes were characterized by PCR and sequencing. Plasmids were characterized by transformation, PCR-based replicon typing and plasmid multilocus sequence typing (MLST). E. coli genotypes were analysed by MLST. RESULTS: At T0 the prevalence of ESBL/AmpC-producing E. coli ranged from 18% to 26%. These were predominantly isolates carrying blaCTX-M-1 and blaCTX-M-15 genes, located on various plasmids and E. coli sequence types (STs). Farm 1 was negative for ESBL/AmpC-producing E. coli after T0. Farm 2 showed an increase up to 37% at T3, which subsequently decreased gradually to 0% at T10. The presence from T3 to T10 on farm 2 was mainly caused by the clonal spread of a multiresistant E. coli ST57 harbouring blaCTX-M-14 on an IncF F2:A-:B- plasmid. Farm 3 showed a gradual decrease in prevalence to 1.4% at T10, with a relative increase of the identical clonal variant as shown for farm 2. A second clonal variant found in farm 3 was a multiresistant E. coli ST10 harbouring blaCTX-M-14 on an IncK plasmid. CONCLUSIONS: The prevalence of ESBL/AmpC-producing E. coli decreased over time. A clonal spread was observed on farm 2 and farm 3, illustrative of the complex dynamics probably associated with the use of antimicrobials.
    Livestock-associated MRSA prevalence in veal calf production is associated with farm hygiene, use of antimicrobials, and age of the calves
    Bos, M.E.H. ; Graveland, H. ; Portengen, L. ; Wagenaar, J.A. ; Heekerik, D.J.J. - \ 2012
    Preventive Veterinary Medicine 105 (2012)1-2. - ISSN 0167-5877 - p. 155 - 159.
    resistant staphylococcus-aureus - strains - origin - meat
    Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is highly prevalent in pork and veal production chains. In this study, we used data from a crosssectional survey on 2151 calves from 102 veal calf farms to identify potential risk factors, with the goal of reducing MRSA prevalence by developing intervention strategies. Overall, calves from rose veal farms had a lower risk of LA-MRSA carriage than calves from white veal farms. Data were analysed separately for white and rose veal calves, because management systems of the two production chains were largely different. Group treatment with antimicrobials appeared to be a risk factor for MRSA carriage in white veal calves in univariate analyses, but was not included in the final multiple regression model that included age of the calves and rodent control. Number of start treatment days was positively associated with LA-MRSA carriage in rose veal calves, and was the only risk factor selected for the final multiple regression model for this group. Interpretation of the results from this cross-sectional study is complicated by the strong correlation between antimicrobial use, LA-MRSA carriage and age of the calves. Other age-related factors may be more influential. However, taken together these findings emphasize the need for prudent use of antimicrobials, and point to improvement of farm hygiene as a control measure.
    Dynamics of MRSA carriage in veal calves: A longitudinal field study
    Graveland, H. ; Wagenaar, J.A. ; Verstappen, K.M.H.W. ; Oosting-van Schothorst, I. ; Heederik, D.J.J. ; Bos, M.E.H. - \ 2012
    Preventive Veterinary Medicine 107 (2012)3-4. - ISSN 0167-5877 - p. 180 - 186.
    resistant staphylococcus-aureus - methicillin-resistant - escherichia-coli - pig farms - animals - transmission - epidemiology - flora - swine
    Colonization of Methicillin-Resistant Staphylococcus aureus (MRSA) in food producing animals has public health implications, but intervention targets have not yet been identified. In this field study occurrence and dynamics of MRSA in veal calves were investigated longitudinally on three farms. Determinants generally associated with MRSA carriage, such as environmental exposure and antimicrobial use, were explored. In addition, the reliability and reproducibility of MRSA detection in nasal samples from veal calves were investigated as well as the additional value of rectal samples to establish MRSA status of an individual animal. On these three farms, MRSA prevalence and MRSA air loads in stables rapidly increased during the production cycle, especially after releasing calves from their individual houses, but not simultaneously with or directly after treatment with antimicrobials. These observations constitute the hypothesis that antimicrobial use may not necessarily be the only condition for MRSA transmission in veal calves, but indicate that other factors may contribute to transmission as well. MRSA in calves was present both nasally and rectally. The reproducibility and repeatability of the nasal samples were moderate. The results of this study give a better understanding of the dynamics of MRSA in a field situation.
    Livestock-associated MRSA ST398 carriage in pig slaughterhouse workers related to quantitative environmental exposure
    Gilbert, M.J. ; Bos, M.E.H. ; Duim, B. ; Urlings, H.A.P. ; Heres, L. ; Wagenaar, J.A. ; Heederik, D.J.J. - \ 2012
    Occupational and Environmental Medicine 69 (2012)7. - ISSN 1351-0711 - p. 472 - 478.
    resistant staphylococcus-aureus - time pcr assay - methicillin-resistant - high prevalence - netherlands - endocarditis - infections - personnel - bacteria - contact
    Objectives To assess livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) carriage among workers in pig slaughterhouses and assess associated risk factors, including occupational exposure to LA-MRSA. Methods A cross-sectional study in three Dutch pig slaughterhouses was undertaken. Nasal swabs of participants were taken. Nasal swabs and surface wipes, air and glove samples were screened for presence of methicillin-resistant Staphylococcus aureus (MRSA). MRSA was quantitatively determined on gloves and in air samples by culturing and real-time PCR. Results 11 of 341 (3.2%) participants were identified as nasal MRSA carriers. MRSA-positive workers were predominantly found at the start of the slaughter process. Major risk factors for carriage were working in the lairage and working in the scalding and dehairing area. Most nasal isolates (73%) belonged to the LA-MRSA clone ST398. MRSA ST398-positive environmental samples were found throughout the slaughter process. A clear decrease was seen along the slaughterline in the number of MRSA-positive samples and in the MRSA amount per sample. Conclusions This study showed that working in the lairage area or scalding and dehairing area were the major risk factors for MRSA carriage in pig slaughterhouse workers, while the overall prevalence of MRSA carriage is low. Occupational exposure to MRSA decreased along the slaughterline, and the risk of carriage showed a parallel decrease.
    Back-calculation method shows that within-flock transmission of highly pathogenic avian influenza (H7N7) virus in the Netherlands is not influenced by housing risk factors
    Bos, M.E.H. ; Nielen, M. ; Koch, G. ; Bouma, A. ; Jong, M.C.M. de; Stegeman, J.A. - \ 2009
    Preventive Veterinary Medicine 88 (2009)4. - ISSN 0167-5877 - p. 278 - 285.
    poultry farms - chickens - epidemic - susceptibility - vaccination - infection - turkeys - spread - age
    To optimize control of an avian influenza outbreak knowledge of within-flock transmission is needed. This study used field data to estimate the transmission rate parameter (ß) and the influence of risk factors on within-flock transmission of highly pathogenic avian influenza (HPAI) H7N7 virus in the 2003 epidemic in The Netherlands. The estimation is based on back-calculation of daily mortality data to fit a susceptible-infectious-dead format, and these data were analysed with a generalized linear model. This back-calculation method took into account the uncertainty of the length of the latent period, the survival of an infection by some birds and the influence of farm characteristics. After analysing the fit of the different databases created by back-calculation, it could be concluded that an absence of the latency period provided the best fit. The transmission rate parameter (ß) from these field data was estimated at 4.50 per infectious chicken per day (95% CI: 2.68¿7.57), which was lower than what was reported from experimental data. In contrast to general belief, none of the studied risk factors (housing system, flock size, species, age of the birds in weeks and date of depopulation) had significant influence on the estimated ß
    Effect of H7N1 vaccination on highly pathogenic avian influenza H7N7 virus transmission in turkeys
    Bos, M.E.H. ; Nielen, M. ; Koch, G. ; Stegeman, A. ; Jong, M.C.M. de - \ 2008
    Vaccine 26 (2008)50. - ISSN 0264-410X - p. 6322 - 6328.
    infection - chickens - susceptibility - patterns - efficacy - h5
    This study describes the results of a transmission experiment with highly pathogenic avian influenza (HPAI) H7N7 virus in 12-week-old turkeys. Cloacal and tracheal swabs as well as serum samples were taken to monitor the infection both in inoculated and in susceptible contact turkeys, which were all either unvaccinated, vaccinated once or vaccinated twice with H7N1. Swabs were tested by real-time RT-PCR and serum samples with hemagglutination inhibition test (HI). Unvaccinated contact birds had a mean infectious period of 6.2 days, and an estimated transmission rate parameter of 1.26 per infectious bird per day. However, no virus shedding was found in inoculated vaccinated turkeys and thus we concluded that vaccination with H7N1 protected against challenge with HPAI H7N7 virus.
    Using field mortality data to estimate transmission parameters for HPAI H7N7
    Bos, M.E.H. ; Boven, R.M. van; Bouma, A. ; Elbers, A.R.W. ; Nodelijk, G. - \ 2007
    Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data
    Bos, M.E.H. ; Boven, R.M. van; Nielen, M. ; Bouma, A. ; Elbers, A.R.W. ; Nodelijk, G. ; Koch, G. ; Stegeman, A. ; Jong, M.C.M. de - \ 2007
    Veterinary Research 38 (2007)3. - ISSN 0928-4249 - p. 493 - 504.
    classical swine-fever - realistic distributions - infectious periods - epidemic models - transmission - netherlands - outbreaks - chickens - h5n1
    Despite continuing research efforts, knowledge of the transmission of the highly pathogenic avian influenza (HPAI) virus still has considerable gaps, which complicates epidemic control. The goal of this research was to develop a model to back-calculate the day HPAI virus is introduced into a flock, based on within-flock mortality data. The back-calculation method was based on a stochastic SEIR (susceptible (S) - latently infected (E) - infectious (I) - removed (= dead; R)) epidemic model. The latent and infectious period were assumed to be gamma distributed. Parameter values were based on experimental H7N7 within-flock transmission data. The model was used to estimate the day of virus introduction based on a defined within-flock mortality threshold (detection rule for determining AI). Our results indicate that approximately two weeks can elapse before a noticeable increase in mortality is observed after a single introduction into a flock. For example, it takes twelve (minimum 11 - maximum 15) days before AI is detected if the detection rule is fifty dead chickens on two consecutive days in a 10 000 chicken flock (current Dutch monitoring rule for notification). The results were robust for flock size and detection rule, but sensitive to the length of the latent and infectious periods. Furthermore, assuming multiple introductions on one day will result in a shorter estimated period between infection and detection. The implications of the model outcomes for detecting and tracing outbreaks of H7N7 HPAI virus are discussed.
    Estimating the Moment of H7N7 HPAI Virus Introduction into a Poultry Flock, Based on Mortality Data.
    Bos, M.E.H. ; Boven, R.M. van; Nielen, M. ; Bouma, A. ; Elbers, A.R.W. ; Nodelijk, G. ; Koch, G. ; Stegeman, J.A. ; Jong, M.C.M. de - \ 2007
    Using field mortality data to estimate transmission parameters for HPAI H7N7.
    Bos, M.E.H. ; Boven, R.M. van; Bouma, A. ; Elbers, A.R.W. ; Nodelijk, G. ; Koch, G. ; Nielen, M. ; Stegeman, J.A. ; Jong, M.C.M. de - \ 2007
    Can short-term frustration facilitate feather pecking in laying hens?
    Rodenburg, T.B. ; Koene, P. ; Bokkers, E.A.M. ; Bos, M.E.H. ; Uitdehaag, K.A. ; Spruijt, B.M. - \ 2005
    Applied Animal Behaviour Science 91 (2005)1-2. - ISSN 0168-1591 - p. 85 - 101.
    gallus-gallus-domesticus - induced aggression - different ages - behavior - chicks - fowl - line - heritability - cannibalism - food
    Feather pecking is a major problem in laying hens. Frustration, i.e. the omission of expected reward, may play a role in the development of feather pecking. In two experiments, we studied if feather pecking could be facilitated by short-term frustration in birds with a high feather pecking phenotype and victims of feather pecking (experiment 1), and in birds with a high or low feather pecking genotype (experiment 2). Furthermore, the motivation to peck a key for a food reward was assessed in birds with a high or low feather pecking genotype in experiment 3, as birds that have a stronger motivation may also react stronger to the omission of a reward. We trained birds to peck a key for a food reward in an automated Skinnerbox and tested them in control and frustration sessions. During frustration, the feeder was covered with Perspex. Frustration did not facilitate feather pecking in either experiment. In experiment 1, birds with a high feather pecking phenotype did show more gentle feather pecking and aggressive pecking than victims of feather pecking during some of the control sessions. Furthermore, victims of feather pecking vocalised more than birds with a high feather pecking phenotype. In experiment 2, birds with a high feather pecking genotype scratched more than birds with a low feather pecking genotype, indicating differences in motivation for foraging or dust-bathing behaviour, which shows a relation to feather pecking. Birds with a low feather pecking genotype also had a stronger motivation to peck at a key for a food reward than birds with a high feather pecking genotype. No evidence was found that feather pecking could be facilitated by short-term frustration in a Skinnerbox. However, differences in reaction to frustration and in motivation to peck a key for a food reward in birds with a high or low feather pecking phenotype or genotype indicate that frustration may still play a role in the development of feather pecking.
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