Central Veterinary Institute CVI

Wageningen, Netherlands

Central Veterinary Institute CVI

Wageningen, Netherlands
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For some microbial species, such as Bacillus anthracis, the etiologic agent of the disease anthrax, correct detection and identification by molecular methods can be problematic. The detection of virulent B. anthracis is challenging due to multiple virulence markers that need to be present in order for B. anthracis to be virulent and its close relationship to Bacillus cereus and other members of the B. cereus group. This is especially the case in environments where build-up of Bacillus spores can occur and several representatives of the B. cereus group may be present, which increases the chance for false-positives. In this study we show the presence of B. anthracis-like bacteria and other members of the B. cereus group in a microbial community within the human environment of the International Space Station and their preliminary identification by using conventional culturing as well as molecular techniques including 16S rDNA sequencing, PCR and real-time PCR. Our study shows that when monitoring the microbial hygiene in a given human environment, health risk assessment is troublesome in the case of virulent B. anthracis, especially if this should be done with rapid, easy to apply and on-site molecular methods.


Hordijk J.,University Utrecht | Hordijk J.,Central Veterinary Institute CVI | Wagenaar J.A.,University Utrecht | Wagenaar J.A.,Central Veterinary Institute CVI | And 7 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2013

Objectives: Several studies on faecal carriage of extended-spectrum β-lactamase (ESBL)/AmpC-producing Escherichia coli have been performed in cattle, but little is known about faecal carriage in veal calves. This study describes the prevalence and molecular characteristics of ESBL/AmpC genes in E. coli isolated from faecal samples of veal calves from 1997 to 2010. Methods: Pooled faecal samples were inoculated using selective enrichment broth and subsequently selective MacConkey agar. All isolates with reduced susceptibility to cefotaxime were screened by PCR and sequencing analysis for the presence of ESBL/AmpC genes. Results: The prevalence of E. coli with reduced susceptibility to cefotaxime showed a discontinuous increasing trend, ranging from 4% in 1998 and 1999 to 39% in 2010. Promoter mutations of the chromosomal ampC gene were present in all years. In 2000, ESBL genes blaCTX-M-1, blaTEM-52 and blaTEM-20 were first observed. Before 2005 themajority of E. coli with reduced susceptibility to cefotaxime harboured ampC promoter mutations. From 2005 onwards the majority harboured blaCTX-M genes, of which blaCTX-M-1 was the most abundant, followed by blaCTX-M-14 and blaCTX-M-15. The diversity of blaCTX-M genes gradually increased from one variant in 2000 to six variants in 2010. The prevalence of blaTEM-52 was relatively low, but it was detected from 2000 onwards. blaCMY and blaSHV were found sporadically. Conclusions: The prevalence and molecular diversity of genes encoding cefotaxime resistance in E. coli isolated from veal calves over a 14 year period showed an increasing trend. From 2005 onwards, blaCTX-M genes were most abundant, especially blaCTX-M-1. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.


Gonzales J.L.,Central Veterinary Institute CVI part of Wageningen UR | Gonzales J.L.,University Utrecht | Elbers A.R.W.,Central Veterinary Institute CVI part of Wageningen UR | van der Goot J.A.,Central Veterinary Institute CVI part of Wageningen UR | And 4 more authors.
Preventive Veterinary Medicine | Year: 2012

Even though low pathogenic avian influenza viruses (LPAIv) affect the poultry industry of several countries in the world, information about their transmission characteristics in poultry is sparse. Outbreak reports of LPAIv in layer chickens have described drops in egg production that appear to be correlated with the virus transmission dynamics. The objective of this study was to use egg production data from LPAIv infected layer flocks to quantify the within-flock transmission parameters of the virus. Egg production data from two commercial layer chicken flocks which were infected with an H7N3 LPAIv were used for this study. In addition, an isolate of the H7N3 LPAIv causing these outbreaks was used in a transmission experiment. The field and experimental estimates showed that this is a virus with high transmission characteristics. Furthermore, with the field method, the day of introduction of the virus into the flock was estimated. The method here presented uses compartmental models that assume homogeneous mixing. This method is, therefore, best suited to study transmission in commercial flocks with a litter (floor-reared) housing system. It would also perform better, when used to study transmission retrospectively, after the outbreak has finished and there is egg production data from recovered chickens. This method cannot be used when a flock was affected with a LPAIv with low transmission characteristics (R0<2), since the drop in egg production would be low and likely to be confounded with the expected decrease in production due to aging of the flock. Because only two flocks were used for this analysis, this study is a preliminary basis for a proof of principle that transmission parameters of LPAIv infections in layer chicken flocks could be quantified using the egg production data from affected flocks. © 2012 Elsevier B.V.


Gonzales J.L.,Central Veterinary Institute CVI part of Wageningen UR | Gonzales J.L.,University Utrecht | Stegeman J.A.,University Utrecht | Koch G.,Central Veterinary Institute CVI | And 2 more authors.
Influenza and other Respiratory Viruses | Year: 2013

Background Targeted risk-based surveillance of poultry types (PT) with different risks of introduction of low pathogenic avian influenza virus (LPAIv) infection may improve the sensitivity of surveillance. Objective To quantify the rate of introduction of LPAIv infections in different PT. Methods Data from the Dutch LPAIv surveillance programme (2007-2010) were analysed using a generalised linear mixed and spatial model. Results Outdoor-layer, turkey, duck-breeder and meat-duck, farms had a 11, 8, 24 and 13 times higher rate of introduction of LPAIv than indoor-layer farms, respectively. Conclusion Differences in the rate of introduction of LPAIv could be used to (re)design a targeted risk-based surveillance programme. © 2012 Blackwell Publishing Ltd.


PubMed | Erasmus Medical Center, National Health Research Institute, University Utrecht, GD Animal Health Service AHS and Central Veterinary Institute CVI
Type: Journal Article | Journal: PloS one | Year: 2014

Current avian influenza surveillance in poultry primarily targets subtypes of interest for the veterinary sector (H5, H7). However, as virological and serological evidence suggest, surveillance of additional subtypes is important for public health as well as for the poultry industry. Therefore, we developed a protein microarray enabling simultaneous identification of antibodies directed against different HA-types of influenza A viruses in chickens. The assay successfully discriminated negative from experimentally and naturally infected, seropositive chickens. Sensitivity and specificity depended on the cut-off level used but ranged from 84.4% to 100% and 100%, respectively, for a cut off level of 1:40, showing minimal cross reactivity. As this testing platform is also validated for the use in humans, it constitutes a surveillance tool that can be applied in human-animal interface studies.


Mulders M.N.,National Institute of Public Health and the Environment RIVM | Haenen A.P.J.,National Institute of Public Health and the Environment RIVM | Geenen P.L.,National Institute of Public Health and the Environment RIVM | Vesseur P.C.,Association of Dutch Poultry Processing Industries NEPLUVI | And 10 more authors.
Epidemiology and Infection | Year: 2010

To determine methicillin-resistant Staphylococcus aureus (MRSA) carriage in poultry and slaughterhouse personnel, 40 Dutch broiler flocks, in six slaughterhouses and 466 personnel were sampled. Of the employees, 26 were positive (56%), indicating a higher risk of exposure when compared to the general Dutch population (01%). This risk was significantly higher for personnel having contact with live animals (52%) - especially hanging broilers on the slaughterline (200%) - than for all other personnel (19%). Conventional electric stunning conferred a significantly higher risk of MRSA carriage for employees than CO2 stunning (97% vs. 20%). A total of 405 broilers were sampled upon their arrival at the slaughterhouse, of which 69% were positive. These broilers originated from 40 Dutch slaughter flocks of which 350% were positive. MRSA contamination in the different compartments of slaughterhouses increased during the production day, from 8% to 35%. Of the 119 MRSA isolates, predominantly livestock-associated MRSA ST398 was found, although 277% belonged to ST9 (spa type t1430). There is an increased risk of MRSA carriage in personnel working at broiler slaughterhouses, particularly those having contact with live animals. © Cambridge University Press 2010.


Garcia P.,University of Oviedo | Garcia P.,University of La Coruña | Hopkins K.L.,Public Health England | Garcia V.,University of Oviedo | And 7 more authors.
PLoS ONE | Year: 2014

Plasmids encoding resistance and virulence properties in multidrug resistant (MDR) Salmonella enterica (S.) serovar Typhimurium monophasic variant 4,[5],12:i:- isolates recovered from pigs and humans (2006-2008) in Europe were characterised. The isolates were selected based on the detection by PCR-amplification of S. Typhimurium virulence plasmid pSLT genes and were analysed by multi-locus sequence typing (MLST). The resistance genes present in the isolates and the association of these genes with integrons, transposons and insertion sequences were characterised by PCR-sequencing, and their plasmid location was determined by alkaline lysis and by S1-nuclease pulsed-field gel electrophoresis (PFGE) Southern-blot hybridisation. Plasmids were further analysed by replicon typing, plasmid MLST and conjugation experiments. The 10 S. 4,[5],12,i:- selected isolates belonged to ST19. Each isolate carried a large plasmid in which MDR with pSLT-associated virulence genes were located. After analysis, eight different plasmids of three incompatibility groups (IncA/C, IncR and IncF) were detected. Two IncA/C plasmids represented novel variants within the plasmid family of the S. 4,[5],12:i:- Spanish clone, and carried an empty class 1 integron with a conventional qacEΔ1-sul1 3′ conserved segment or an In-sul3 type III with estX-psp-aadA2-cmlA1-aadA1-qacH variable region linked to tnpA440-sul3, part of Tn2, Tn21 and Tn1721 transposons, and ISCR2. Four newly described IncR plasmids contained the resistance genes within In-sul3 type I (dfrA12-orfF-aadA2-cmlA1-aadA1-qacH/tnpA440-sul3) and part of Tn10 [tet(B)]. Two pSLT-derivatives with FIIs-ST1+FIB-ST17 replicons carried cmlA1-[aadA1-aadA2]-sul3-dfrA12 and blaTEM-1 genes linked to an In-sul3 type I integron and to Tn2, respectively. In conclusion, three emerging European clones of S. 4,[5],12:i:- harboured MDR plasmids encoding additional virulence functions that could contribute significantly to their evolutionary success. © 2014 García et al.


Rutten N.,Wageningen University | Gonzales J.L.,Central Veterinary Institute CVI | Gonzales J.L.,University Utrecht | Elbers A.R.W.,Central Veterinary Institute CVI | Velthuis A.G.J.,Wageningen University
PLoS ONE | Year: 2012

Background: As low pathogenic avian influenza viruses can mutate into high pathogenic viruses the Dutch poultry sector implemented a surveillance system for low pathogenic avian influenza (LPAI) based on blood samples. It has been suggested that egg yolk samples could be sampled instead of blood samples to survey egg layer farms. To support future decision making about AI surveillance economic criteria are important. Therefore a cost analysis is performed on systems that use either blood or eggs as sampled material. Methodology/Principal Findings: The effectiveness of surveillance using egg or blood samples was evaluated using scenario tree models. Then an economic model was developed that calculates the total costs for eight surveillance systems that have equal effectiveness. The model considers costs for sampling, sample preparation, sample transport, testing, communication of test results and for the confirmation test on false positive results. The surveillance systems varied in sampled material (eggs or blood), sampling location (farm or packing station) and location of sample preparation (laboratory or packing station). It is shown that a hypothetical system in which eggs are sampled at the packing station and samples prepared in a laboratory had the lowest total costs (i.e. € 273,393) a year. Compared to this a hypothetical system in which eggs are sampled at the farm and samples prepared at a laboratory, and the currently implemented system in which blood is sampled at the farm and samples prepared at a laboratory have 6% and 39% higher costs respectively. Conclusions/Significance: This study shows that surveillance for avian influenza on egg yolk samples can be done at lower costs than surveillance based on blood samples. The model can be used in future comparison of surveillance systems for different pathogens and hazards. © 2012 Rutten et al.


Elbers A.R.W.,Central Veterinary Institute CVI | Meiswinkel R.,Maria de Monte | van Weezep E.,Central Veterinary Institute | Kooi E.A.,Central Veterinary Institute | van der Poel W.H.M.,Central Veterinary Institute
Transboundary and Emerging Diseases | Year: 2015

A total of 130 pools of Culicoides biting midges collected between May and September 2012 in the Netherlands were assayed for Schmallenberg virus (SBV). The Culicoides midges were caught in the same area as where in 2011 a high proportion of Culicoides pools tested positive for SBV, in majority with a high viral load (Ct values between 20 and 30). Two of a total of 42 pools comprising 50 midges/pool of the Obsoletus complex from the 2012 collection tested weak positive (Ct values: 34.96 and 37.66), indicating a relatively low viral load. On an individual midge level, the proportion of SBV-infected Culicoides of the Obsoletus complex caught in the same area and in a comparable period of the year was significantly lower in 2012 (0.1% = 1 per 1050 tested) compared with 2011 (0.56% = 13 per 2300 tested). © 2013 Blackwell Verlag GmbH.


PubMed | Central Veterinary Institute CVI and Santa Maria del Monte
Type: Journal Article | Journal: Veterinary parasitology | Year: 2014

Host preference is an important determinant of feeding behaviour in biting insects and a critical component in the transmission of vector-borne diseases. The aim of the study was to quantify Culicoides (Diptera: Ceratopogonidae) host preferences and biting rates using tethered livestock at pasture (a dairy cow and a sheep) and to compare the numbers of biting midges aspirated off them to those captured simultaneously in a black-light suction trap acting as a surrogate host. Culicoides collections were made hourly over seven hours (from five hours before official sunset to two hours after) between 27 May and 19 June, 2013 at a dairy farm (eastern Netherlands). The study involved 13 replicates of a site host randomised design. Culicoides collected by black-light suction trap and by direct aspiration were identified to species morphologically and age-graded. The C. obsoletus complex, C. dewulfi and C. pulicaris predominated on the back and flanks of the animals, C. punctatus on the belly, and C. chiopterus on the legs. Using comparable collection periods, 9.3 times (95% confidence interval: 8.6-10.0) more Culicoides were caught on the cow than on the sheep and 25.4 times (95% confidence interval: 18.4-35.1) less in the black-light suction trap compared to the sheep. Mean Culicoides biting rates on the cow across the 7-h collection period were 4.6, 3.5, 1.0, 1.0 and 0.5 min(-1) for C. dewulfi, the C. obsoletus complex, C. chiopterus, C. punctatus and C. pulicaris, respectively; for the sheep they were 0.6, 0.4 and 0.1 min(-1) for the C. obsoletus complex, C. dewulfi and C. punctatus, respectively. Though midges were aspirated off livestock during each of the seven hours, they only began to appear in the black-light suction trap 5h later, from sunset onwards. After sunset, its efficacy improved markedly, but occurred when midge activity overall had begun to decline. Though it was quite accurate in ranking Culicoides species abundance, the black-light suction trap proved to be of limited value for determining hours of peak biting activity, levels of abundance, and host preference, in Culicoides.

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