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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    Rapid Assessment of Floating Macroplastic Transport in the Rhine
    Vriend, Paul ; Calcar, Caroline van; Kooi, Merel ; Landman, Harm ; Pikaar, Remco ; Emmerik, Tim van - \ 2020
    Frontiers in Marine Science 7 (2020). - ISSN 2296-7745
    flux measurements - hydrology - macroplastic - marine litter - passive sampling - riverine plastic - visual sampling

    Most marine litter pollution is assumed to originate from land-based sources, entering the marine environment through rivers. To better understand and quantify the risk that plastic pollution poses on aquatic ecosystems, and to develop effective prevention and mitigation methods, a better understanding of riverine plastic transport is needed. To achieve this, quantification of riverine plastic transport is crucial. Here, we demonstrate how established methods can be combined to provide a rapid and cost-effective characterization and quantification of floating macroplastic transport in the River Rhine. We combine visual observations with passive sampling to arrive at a first-order estimate of macroplastic transport, both in number (10–75 items per hour) and mass per unit of time (1.3–9.7 kg per day). Additionally, our assessment gives insight in the most abundant macroplastic polymer types the downstream reach of the River Rhine. Furthermore, we explore the spatial and temporal variation of plastic transport within the river, and discuss the benefits and drawbacks of current sampling methods. Finally, we present an outlook for future monitoring of major rivers, including several suggestions on how to expand the rapid assessment presented in this paper.

    An avian influenza virus H6N1 outbreak in commercial layers: case report and reproduction of the disease
    Landman, W.J.M. ; Germeraad, Evelien ; Kense, M.J. - \ 2018
    Avian Pathology 48 (2018)2. - ISSN 0307-9457 - p. 1 - 35.
    An outbreak of low pathogenic avian influenza (LPAI) subtype H6N1 (intravenous pathogenicity index = 0.11) infection occurred in four productive brown layer flocks on three farms in the Netherlands within a period of two months. The farms were located at a maximum distance of 4.6 km from each other. The infections were associated with egg production drops up to 74%, pale eggshells and persisting high mortality up to 3.2% per week. Three flocks were slaughtered prematurely as they were not profitable anymore. Newcastle disease, infectious bronchitis, egg drop syndrome and Mycoplasma gallisepticum infections could very likely be excluded as cause of or contributor to the condition in the field. Also, the anticoccidial drug nicarbazin, which can cause egg production drops and eggshell decolouration, was not detected in eggs from affected flocks. Furthermore, post mortem examinations revealed no lesions indicative of bacterial infection. Moreover, bacteriological analysis of hens was negative. The condition was reproduced in commercial brown layers after intratracheal inoculation with virus isolates from affected flocks. It is concluded that the LPAI H6N1 virus is very likely the only cause of the disease. An overview of main manuscripts published since 1976 describing non-H5 and non-H7 avian influenza (AI) virus infections in chickens and their biological significance is included in the present study, in which once more is shown that not only high pathogenic AI virus subtypes H5 and H7 can be detrimental to flocks of productive layers, but also non-H5 and non-H7 LPAI viruses (H6N1 virus). RESEARCH HIGHLIGHTS LPAI H6N1 can be detrimental to productive layers Detrimental effects are severe egg drop and persistent high mortality LPAI H6N1 virus outbreak seems to be self-limiting.
    In vivo screening of five phytochemicals/extracts and a fungal immunomodulatory protein against colibacillosis in broilers
    Peek, H.W. ; Halkes, S.B.A. ; Mes, J.J. ; Landman, W.J.M. - \ 2013
    Veterinary Quarterly 33 (2013)3. - ISSN 0165-2176 - p. 132 - 138.
    dietary betaine - avian eimeria - herb polysaccharides - anticoccidial drugs - immune-responses - coccidiosis - tenella - chicks - resistance - performance
    Besides the anticoccidial drug resistance problem, increasing consumer concerns about food safety and residues have propelled the quest for alternative prevention and control strategies amongst which phytotherapy has gained appeal due to a renewed interest in natural medicine.Objective: The objective was in vivo screening of four phytochemicals/extracts and a fungal immunomodulatory protein (FIP) against an Eimeria acervulina infection in broilers.Animals and methods: Four phytochemicals/extracts (extract from Echinacea purpurea, betaine (Betain™), curcumin, carvacrol (two different doses)), and a recombinant FIP from Ganoderma lucidum cloned and expressed in Escherichia coli were investigated for their anticoccidial potential. The experiment was conducted in a battery cage trial with 54 cages of eight birds each. Broilers infected with E. acervulina (a low and high infection dose of 104 and 105 sporulated oocysts, respectively) and treated with the phytochemicals/extracts or the FIP were compared with broilers treated with the anticoccidial salinomycin sodium (Sacox®) and with an untreated uninfected and an untreated infected control group. Coccidiosis lesion scores, body weight gains and oocyst shedding were used as parameters.Results: The results showed a coccidiosis infection dose effect on the mean coccidiosis lesion scores. The phytochemicals/extracts and the FIP failed to reduce coccidiosis lesion scores and oocyst shedding, while salinomycin efficiently controlled the E. acervulina infection and enabled significantly higher body weight gains.Conclusion: In conclusion, the selected phytochemicals/extracts and the FIP did not reduce the lesions of an experimentally induced E. acervulina infection.
    In vivo screening of five phytochemicals/extracts and a fungal immunomodulatory protein against colibacillosis in broilers
    Peek, H.W. ; Halkes, S.B.A. ; Tomassen, M.M.M. ; Mes, J.J. ; Landman, W.J.M. - \ 2013
    Avian Pathology 42 (2013)3. - ISSN 0307-9457 - p. 235 - 247.
    infectious-bronchitis virus - eimeria-tenella - immune-responses - dietary betaine - antimicrobial resistance - herb polysaccharides - commercial broilers - ganoderma-lucidium - escherichia-coli - chicks
    Five phytochemicals/extracts (an extract from Echinacea purpurea, a ß-glucan-rich extract from Shiitake, betaine [Betain™], curcumin from Curcuma longa [turmeric] powder, carvacrol and also a recombinant fungal immunomodulatory protein [FIP] from Ganoderma lucidum) cloned and expressed in Escherichia coli were investigated for their anticolibacillosis potential in three chicken experiments, which were conducted in floor pens. Birds that were inoculated with E. coli intratracheally were treated with the phytochemicals/extracts or the FIP and compared with doxycycline-medicated and non-medicated infected broilers. Non-medicated and non-infected birds were used as negative controls. Mortality, colibacillosis lesions and body weight gains were used as parameters. Considering the sum of dead birds and chickens with generalized colibacillosis per group, there was no significant difference between the positive control groups and birds treated with phytochemicals/extracts or the FIP. In contrast, doxycycline-treated birds showed significantly lower mortality and generalized colibacillosis. Moreover, none of the phytochemicals/extracts and the FIP improved recovery from colibacillosis lesions, while all doxycycline-treated broilers recovered completely. The negative control birds and doxycycline-treated groups consistently showed the highest weight gains. Pulsed-field gel electrophoresis of reisolates showed that they were genetically indistinguishable from the inoculation strain. In conclusion, none of the tested phytochemicals/extracts and the FIP significantly reduced the E. coli-induced mortality and generalized colibacillosis, and nor did they improve recovery from colibacillosis lesions.
    Enterococcus hirae-associated endocarditis outbreaks in broiler flocks: clinical and pathological characteristics and molecular epidemiology.
    Velkers, F.C. ; Graaf-Blois, L. Van de; Wagenaar, J.A. ; Westendorp, S.T. ; Bergen, M.A.P. Van; Dwars, R.M. ; Landman, W.J.M. - \ 2011
    Veterinary Quarterly 31 (2011)1. - ISSN 0165-2176 - p. 3 - 17.
    amyloid arthropathy - bacterial endocarditis - durans infection - chickens - faecalis - identification - septicemia - encephalomalacia - arthritis - heart
    Background: Enterococcus hirae-associated endocarditis, characterized by a peak in mortality during the second week of the grow-out, and occasionally lameness, was diagnosed at Dutch broiler farms. Objectives: Field cases were studied to increase knowledge on clinical and pathological characteristics, pathogenesis and epidemiology of these infections. Animals and methods. In total, 1266 birds of 25 flocks from 12 farms were examined. Post-mortem examinations, bacteriology, histopathology, PCR and DNA fingerprinting was carried out. Six flocks were followed longitudinally (n¿=¿1017 birds). Results: Average mortality was 4.1% for the entire grow-out, of which 36% was attributed to endocarditis. Fibrinous thromboendocarditis of the right atrioventricular (AV) valve was found in 24% of hearts, compared to 7% and 4% with lesions of left and both AV valves, respectively. Thrombotic lesions were found in 24% (n¿=¿432) of lungs, but only in larger branches of the Arteria pulmonalis. Occasionally, thrombi were found in the Arteria ischiadica externa and in liver and brain vessels. Enterococcus was cultured from 54% (n¿=¿176) of heart and in 75% (n¿=¿28), 62% (n¿=¿106) and 31% (n¿=¿16) of liver, bone marrow and lung samples, respectively. Further identification, using the Rapid ID Strep 32 API system and a PCR targeting mur-2 and mur-2(ed) genes was carried out on a subset of Enterococcus positive isolates (n¿=¿65): both techniques identified the isolates as Enterococcus hirae. Pulsed-field gel electrophoresis did not indicate evidence of clonality between farms and flocks. Conclusions: The relevance of these findings for pathogenesis and epidemiology of E. hirae infections is discussed. Clinical importance. This study may facilitate diagnosis of field cases and may contribute to the design of further research and development of control measures
    Scrubber capabilities to remove airborne microorganisms and other aerial pollutants from the exhaust air of animal houses
    Aarnink, A.J.A. ; Landman, W.J.M. ; Melse, R.W. ; Zhao, Y. ; Ploegaert, J.P.M. ; Huynh, T.T.T. - \ 2011
    Transactions of the ASABE / American Society of Agricultural and Biological Engineers 54 (2011)5. - ISSN 2151-0032 - p. 1921 - 1930.
    henrys law constant - operations - water - acid
    Two studies were conducted to assess the efficiency of air scrubbers to reduce airborne microorganisms in the exhaust air from animal houses. First, in a field study, the effects of a bio-scrubber and an acid scrubber on total bacterial counts were assessed. Higher bacterial counts were found in the outlet air compared to the inlet air of a bio-scrubber (increase from 6.1 × 104 to 2.4 × 105 CFU m-3), while an acid scrubber with sulfuric acid reduced bacterial emissions from 2.7 × 105 to 8.4 × 104 CFU m-3. Second, in a laboratory study, the effects of three disinfectants, added to the circulating water of an experimental air scrubber, on reductions of bacteria and virus were tested and compared with the effect of using only water. The air to the scrubber was extracted from four isolators each harboring seven roosters. Enterococcus faecalis and Gumboro vaccine virus were aerosolized in the air of one of the isolators. Hydrogen peroxide (H2O2; 0.6%), peracetic acid (CH3CO3H; a solution of 0.13% acetic acid, 0.6% peroxide, and 0.13% peracetic acid), or ozone (O3; 0.015%) were used as disinfectants. Peracetic acid was the only disinfectant that reduced bacteria and virus concentrations to below the sampler detection limits. We conclude that an acid scrubber with sulfuric acid is very useful at reducing ammonia emissions to the atmosphere but cannot significantly prevent emissions of microorganisms. Peracetic acid has a high potential to reduce these emissions and could replace or supplement sulfuric acid in existing scrubbers during periods of high risk of disease outbreak.
    Investigation of the Efficiencies of Bioaerosol Samplers for Collecting Aerosolized Bacteria Using a Fluorescent Tracer. II: Sampling Efficiency and Half-Life Time
    Zhao, Y. ; Aarnink, A.J.A. ; Doornenbal, P. ; Huynh, T.T.T. ; Groot Koerkamp, P.W.G. ; Landman, W.J.M. ; Jong, M.C.M. de - \ 2011
    Aerosol Science and Technology 45 (2011)3. - ISSN 0278-6826 - p. 432 - 442.
    escherichia-coli-b - relative-humidity - enterococcus-faecalis - airborne survival - performance - viruses - air - microorganisms - enumeration - rotavirus
    Using uranine as a physical tracer, this study assessed the sampling efficiencies of four bioaerosol samplers (Andersen 6-stage impactor, all glass impinger “AGI-30,” OMNI-3000, and Airport MD8 with gelatin filter) for collecting Gram-positive bacteria (Enterococcus faecalis), Gram-negative bacteria (Escherichia coli and Campylobacter jejuni), and bacteria without cell wall (Mycoplasma synoviae) which were aerosolized in a HEPA isolator. In addition, the half-life times of these bacteria in aerosols were estimated. The uranine concentrations collected by the samplers were used for calculating the physical efficiencies, and the bacteria/uranine ratios were used for calculating the biological efficiencies. The results show the Airport MD8 had the highest physical efficiency. Compared with the Airport MD8, the physical efficiencies of the AGI-30 and the OMNI-3000 were 74% and 49%, respectively. A low physical efficiency of the Andersen impactor (18%) was obtained, but it was mainly caused by the incomplete recovery of uranine when handling the air samples, so could not be ascribed to the sampler efficiency. Both the Andersen impactor and the AGI-30 showed high biological efficiencies for all four bacterial species. The biological efficiencies of the OMNI-3000 for C. jejuni (1%) and of the Airport MD8 for E. coli (38%) and C. jejuni (2%) were significantly lower than 100%, indicating that their sampling stresses inactivated the bacterial culturability. The half-life times at 21-23°C temperature and 80-85% relative humidity were 43.3 min for E. faecalis, 26.7 min for M. synoviae, 21.2 min for E. coli, and 4.0 min for C. jejuni in the air.
    Investigation of the Efficiencies of Bioaerosol Samplers for Collecting Aerosolized Bacteria Using a Fluorescent Tracer. I: Effects of Non-sampling Processes on Bacterial Culturability
    Zhao, Y. ; Aarnink, A.J.A. ; Doornenbal, P. ; Huynh, T.T.T. ; Groot Koerkamp, P.W.G. ; Jong, M.C.M. de; Landman, W.J.M. - \ 2011
    Aerosol Science and Technology 45 (2011)3. - ISSN 0278-6826 - p. 423 - 431.
    airborne particles - relative-humidity - survival - rotavirus - swine - air - microorganisms - temperature - enumeration - barns
    By sampling aerosolized microorganisms, the efficiency of a bioaerosol sampler can be calculated depending on its ability both to collect microorganisms and to preserve their culturability during a sampling process. However, those culturability losses in the non-sampling processes should not be counted toward the sampling efficiency. Prior to the efficiency assessment, this study was designed to investigate the culturability losses in three non-sampling processes: (1) the tracer uranine induced loss; (2) the loss during aerosolization (pre-sampling process); and (3) the bacteria and uranine recovery in air sample handling procedures for the samples of the Andersen 6-stage impactor and the Airport MD8 (post-sampling process). The results indicated that uranine had no significant effect on the culturability of Enterococcus faecalis, Escherichia coli, and Mycoplasma synoviae in suspensions (P > 0.05), but negatively affected the culturability of Campylobacter jejuni (P = 0.01). The culturability of E. faecalis, E. coli, and M. synoviae was not affected by stresses caused by aerosolization (P > 0.05). Only 29% of C. jejuni were still culturable during aerosolization (P = 0.02). In the air sample handling procedures, the four species of bacteria were recovered without significant losses from the samples of the Andersen impactor, but only 33-60% uranine was recovered. E. faecalis, E. coli, and M. synoviae were recovered without significant losses from the samples of the Airport MD8. More C. jejuni was recovered (172%), probably due to multiplication or counting variation. It is suggested that tracer and bacteria should be aerosolized separately when the tracer negatively affects the bacterial culturability. In both pre- and post-sampling processes, losses of bacterial culturability (or multiplication) may occur, which should be taken into account when assessing the efficiencies of bioaerosol samplers.
    Dietary protease can alleviate negative effects of a coccidiosis infection on production performance in broiler chickens
    Peek, H.W. ; Klis, J.D. van der; Vermeulen, B. ; Landman, W.J.M. - \ 2009
    Animal Feed Science and Technology 150 (2009)1-2. - ISSN 0377-8401 - p. 151 - 159.
    eimeria-acervulina - anticoccidial drugs - tenella oocysts - sporulation - intestine - immunity - maxima - model
    Two experiments were conducted to determine the effect of dietary protease on coccidiosis infection, production performance, the intestinal mucus layer thickness, and brush border enzyme activity using broilers challenged with Eimeria spp. laboratory isolates (Eimeria acervulina, E. maxima and E. tenella). In the first study the protease was Supplied at a concentration of 2.5 x 10(4) amylase-DU per kg feed. Broiler chickens were housed in cages and were infected at 10 days of age with 10(4.0) E. acervulina, 10(3.8) E. maxima or 10(3.3) E. tenella sporulated oocysts. Coccidial lesion scores, oocysts shedding, sporulation assessment and daily weight gain were used as parameters to quantify the effect of the protease. In the second study the effects of the protease (supplied at a concentration of 2.5 x 10(4) amylase-DU per kg feed) on the thickness of the mucus adherent layer and sucrase-isomaltase activity (SIA) of three regions (duodenum, jejunum and caecum) of the intestinal tract were determined. In experiment 1, no significant interaction between dietary enzyme supplementation and single Eimeria spp. challenge was observed on body weight gain. However, protease addition to the diet resulted in a significant (P=0.046) higher weight gain after comparing all supplemented and non-supplemented groups. E. maxima infected chickens showed a significant lower body weight gain in comparison with the other Eimeria infected groups. Coccidial lesions were not significantly affected by the dietary protease supplementation
    Assessment of the efficiency of four air bio-samplers after aerosolization of enterococcus faecalis suspensions: a preliminary study
    Yang Zhao, Yang ; Aarnink, A.J.A. ; Groot Koerkamp, P.W.G. ; Jong, M.C.M. de; Doornenbal, P. ; Huynh, T.T.T. ; Landman, W.J.M. - \ 2009
    Effects of elephants on ecosystems and biodiversity
    Kerley, G.I.H. ; Landman, M. ; Kruger, L. ; Owen-Smith, N. ; Balfour, D. ; Boer, W.F. de; Gaylard, A. ; Lindsay, K. ; Slotow, R. - \ 2008
    In: Elephant Management; A Scientific Assessment for South Africa / Scholes, R.J., Mennell, K.G., Johannesburg : Wits University press - ISBN 9781868144792 - p. 146 - 205.
    Detection and quantification of classical swine fever virus in air samples originating from infected pigs and experimentally produced aerosols
    Weesendorp, E. ; Landman, W.J.M. ; Stegeman, A. ; Loeffen, W.L.A. - \ 2008
    Veterinary Microbiology 127 (2008)1-2. - ISSN 0378-1135 - p. 50 - 62.
    mouth-disease virus - hog-cholera - airborne transmission - enterococcus-faecalis - antibody-response - epidemic - netherlands - aerosolization - spread - area
    During epidemics of classical swine fever (CSF), neighbourhood infections occurred where none of the 'traditional' routes of transmission like direct animal contact, swill feeding, transport contact or transmission by people could be identified. A hypothesized route of virus introduction for these herds was airborne transmission. In order to better understand this possible transmission route, we developed a method to detect and quantify classical swine fever virus (CSFV) in air samples using gelatine filters. The air samples were collected from CSFV-infected pigs after experimental aerosolization of the virus. Furthermore, we studied the viability of the virus with time in aerosolized state. Three strains of CSFV were aerosolized in an empty isolator and air samples were taken at different time intervals. The virus remained infective in aerosolized state for at least 30 min with half-life time values ranging from 4.5 to 15 min. During animal experiments, concentrations of 100.3-101.6 TCID50/ m3 CSFV were detected in air samples originating from the air of the pig cages and 100.4-104.0 TCID50/m3 from the expired air of infected animals. This is the first study describing the isolation and quantification of CSFV from air samples originating from infected pigs and their cages, supporting previous findings that airborne transmission of CSF is feasible.
    In vitro antibiotic susceptibility of Dutch Mycoplasma synoviae field isolates originating from joint lesions and the respiratory tract of commercial poultry
    Landman, W.J.M. ; Mevius, D.J. ; Veldman, K.T. ; Feberwee, A. - \ 2008
    Avian Pathology 37 (2008)4. - ISSN 0307-9457 - p. 415 - 420.
    minimum inhibitory concentration - gallisepticum - enrofloxacin - infection - tylosin - oxytetracycline - resistance - mutations - tiamulin - chicks
    The in vitro susceptibility of 17 Dutch Mycoplasma synoviae isolates from commercial poultry to enrofloxacin, difloxacin, doxycycline, tylosin and tilmicosin was examined. Three isolates originated from joint lesions and 14 were from the respiratory tract. The type strain M. synoviae WVU 1853 was included as a control strain. Antibiotic susceptibility was tested quantitatively using the broth microdilution test. Based on initial and final minimum inhibitory concentration values, all tested isolates were susceptible to doxycycline, tylosin and tilmicosin. Two isolates from the respiratory tract were resistant to enrofloxacin and showed intermediate resistance to difloxacin.
    Effects of elephants on ecosystems and biodiversity
    Kerley, G.I.H. ; Landman, M. ; Kruger, L. ; Owen-Smith, N. ; Balfour, D. ; Boer, W.F. de; Gaylard, A. ; Lindsay, K. ; Slotow, R. - \ 2008
    In: The 2007 scientific assessment of elephant management in South Africa / Mennell, K.G., Scholes, R.J., Pretoria : CSIR - p. 101 - 147.
    loxodonta africana - wildbeheer - wild - zuid-afrika - loxodonta africana - wildlife management - wildlife - south africa
    Enterococcus durans-associated endocarditis in broilers
    Velkers, F.C. ; Graaf, L. van der; Wagenaar, J.A. ; Westendorp, S.T. ; Bergen, M.A.P. van; Landman, W.J.M. - \ 2007
    The effect of a live vaccine on the horizontal transmission of Mycoplasma gallisepticum
    Feberwee, A. ; Landman, W.J.M. ; Banniseht-Wysmuller, T.E. von; Klinkenberg, D. ; Vernooij, J.C.M. ; Gielkens, A.L.J. ; Stegeman, J.A. - \ 2006
    Avian Pathology 35 (2006)5. - ISSN 0307-9457 - p. 359 - 366.
    polymerase-chain-reaction - f-strain - infection - synoviae - identification - chickens - poultry - ts-11
    The effect of a live Mycoplasma gallisepticum vaccine on the horizontal transmission of this Mycoplasma species was quantified in an experimental animal transmission model in specific pathogen free White Layers. Two identical trials were performed, each consisting of two experimental groups and one control group. The experimental groups each consisted of 20 birds 21 weeks of age, which were housed following a pair-wise design. One group was vaccinated twice with a commercially available live attenuated M. gallisepticum vaccine, while the other group was not vaccinated. Each pair of the experimental group consisted of a challenged chicken (104 colony-forming units intratracheally) and a susceptible in-contact bird. The control group consisted of 10 twice-vaccinated birds housed in pairs and five individually housed non-vaccinated birds. The infection was monitored by serology, culture and quantitative polymerase chain reaction. The vaccine strain and the challenge strain were distinguished by a specific polymerase chain reaction and by random amplified polymorphic DNA analysis. In both experiments, all non-vaccinated challenged chickens and their in-contact 'partners' became infected with M. gallisepticum. In the vaccinated challenged and corresponding in-contact birds, a total of 19 and 13 chickens, respectively, became infected with M. gallisepticum. Analysis of the M. gallisepticum shedding patterns showed a significant effect of vaccination on the shedding levels of the vaccinated in-contact chickens. Moreover, the Cox Proportional Hazard analysis indicated that the rate of M. gallisepticum transmission from challenged to in-contact birds in the vaccinated group was 0.356 times that of the non-vaccinated group. In addition, the overall estimate of R (the average number of secondary cases infected by one typical infectious case) of the vaccinated group (R = 4.3, 95% confidence interval = 1.6 to 49.9) was significantly lower than that of the non-vaccinated group (R = , 95% confidence interval = 9.9 to ). However, the overall estimate of R in the vaccinated group still exceeded 1, which indicates that the effect of the vaccination on the horizontal transmission M. gallisepticum is insufficient to stop its spread under these experimental conditions.
    Optimization of flushing procedures for embryo recovery in dairy cattle
    Landman, B. ; Ramirez, O. ; Hazeleger, W. ; Merton, S. ; Mullaart, E. - \ 2006
    Detection of egg yolk antibodies reflecting Salmonella enteritidis infections using a surface plasmon resonance biosensor
    Thomas, M.E. ; Bouma, A. ; Eerden, E. van; Landman, W.J.M. ; Knapen, F. van; Stegeman, J.A. ; Bergwerff, A.A. - \ 2006
    Journal of Immunological Methods 315 (2006)1-2. - ISSN 0022-1759 - p. 68 - 74.
    laying hens - typhimurium - chickens - elisa - assay - immunosensor - netherlands - antigens - serum
    A surface plasmon resonance (SPR) biosensor assay was developed on the basis of a lipopolysaccharide antigen of Salmonella enterica serovar enteritidis (S. enterica serovar enteritidis) to detect egg yolk antibodies against S. enterica serovar enteritidis. This biosensor assay was compared to two commercial ELISA kits based on LPS antigen and flagellar antigen. A number of 163 egg yolk and combined egg white and yolk samples from chickens experimentally infected with S. enterica serovar enteritidis and 90 egg yolk and combined egg white and yolk samples from uninfected chickens were analyzed. Receiver operating characteristic analysis of the data calculated a diagnostic sensitivity of 82% and a diagnostic specificity of 100%. The within-day coefficient of variation of a positive internal-control egg yolk was 1%. The SPR biosensor assay was able to detect antibodies in a significantly higher percentage of known positive samples than the commercial ELISA's. The anticipated use of the SPR biosensor assay is to determine the S. enterica serovar enteritidis serostatus of non-vaccinated layer hens
    Systems for eliminating pathogens from exhaust air of animal houses
    Aarnink, A.J.A. ; Landman, W.J.M. ; Melse, R.W. ; Huynh Thi Thanh Thuy, - \ 2005
    In: Livestock Environment VII : proceedings of the seventh international symposium, 18-20 May 2005, Bejing, China / Brown-Brandl, T., Bejing, China : American Society of Agricultural Engineers - p. 239 - 244.
    Recent outbreaks of highly infectious viral diseases like swine fever and avian influenza in The Netherlands have shown that despite extensive bio-security measures aiming at minimizing physical contacts between farms, disease spread could not be halted. Dust in exhaust air from swine and chicken houses may provide a favorable environment in which these viruses and other pathogenic microorganisms can survive and be transported over long distances to other farms. In a field study and in an experimental pilot-scale system, the effects of air scrubbers (bio-scrubber and acid scrubber) were tested. The field test showed higher bacterial counts in the outlet air than in the inlet air of the bio-scrubber (increase from 6.1 x 104 to 24.4 x 104 cfu/m3). An acid scrubber with sulfuric acid reduced bacteria emissions from 27 x 104 to 8.4 x 104 cfu/m3. In the pilot-scale cleaning system, different disinfectants were tested, including hydrogen peroxide, ozone, and peracetic acid. Peracetic acid gave by far the best results. It reduced bacteria and virus emissions to below detectable levels and reduced ammonia emissions by 96%. We conclude that an acid scrubber with sulfuric acid is very useful to reduce ammonia and dust emissions to the atmosphere; however, it cannot prevent the emission of pathogens. Peracetic acid reduces all these emissions, but is too costly to be used continuously. Therefore, an interesting option to prevent disease spread is to replace or supplement sulfuric acid in existing scrubbers with peracetic acid in times of high risk of disease outbreak.
    Cleaning exhaust air from pathogens and environmental pollutants in animal houses
    Aarnink, A.J.A. ; Landman, W.J.M. ; Huynh Thi Thanh Thuy, ; Melse, R.W. ; Gijsel, P. de; Teun, F. - \ 2004
    In: Proceedings of the AgEng 2004 Conference Engineering the future, September 12-16, 2004, Leuven, Belgium Leuven, Belgium : - p. 5 - 5.
    Dust in exhaust air from animal houses could provide a favourable environment in which viruses and bacteria can survive and be spread to other farms. The main objective of air-cleaning systems developed so far was to reduce the emission of environmental pollutants. The objective of the present study was to determine whether commercial air-cleaning systems and an experimental air-cleaning device could achieve both, reduction of emissions of mentioned pollutants and stop the spreading of infectious agents. Two commercially available air-scrubbing systems, biotrickling filter and acid scrubber, were studied with respect to bacterial cleaning. Three different disinfectants (hydrogen peroxide, ozone and per-acetic acid) were studied in a small-scale air scrubber on reductions of ammonia, odour, greenhouse gases, dust, and removal of bacteria and virus. In the biotrickling filter the bacterial count of the air increased during its passage through the filter by 165% (s.e.m. 202%). The acid scrubber reduced the bacteria emission by 64% (s.e.m. 5%). In the small-scale cleaning system with different disinfectants per-acetic acid gave the best results. It reduced bacteria and virus emissions by 100% and ammonia emission by 96%. Odour and greenhouse gas emissions were not significantly affected by per-acetic acid. Three disinfectants gave similar dust reductions, varying from 48 to 88%. From this study it is concluded that the use of per-acetic acid in air-cleaning systems can be very effective in preventing the spreading of pathogens to the environment.
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