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.

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Signaalindicatoren bij handhaving van "Open Normen" voor dierenwelzijn : pilot klimaat in varkensstallen
Vermeer, Herman ; Hopster, Hans - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1017) - 44
dierenwelzijn - dierlijke productie - varkens - huisvesting, dieren - diergedrag - diergezondheid - wetgeving - toezicht - animal welfare - animal production - pigs - animal housing - animal behaviour - animal health - legislation - surveillance
EU-approved rapid tests might underestimate bovine spongiform encephalopathy infection in goats
Meloni, Daniela ; Bozzetta, Elena ; Langeveld, Jan P.M. ; Groschup, Martin H. ; Goldmann, Wilfred ; Andrèoletti, Olivier ; Lantier, Isabelle ; Keulen, Lucien Van; Bossers, Alex ; Pitardi, Danilo ; Nonno, Romolo ; Sklaviadis, Theodoros ; Ingravalle, Francesco ; Peletto, Simone ; Colussi, Silvia ; Acutis, Pier Luigi - \ 2017
Journal of Veterinary Diagnostic Investigation 29 (2017)2. - ISSN 1040-6387 - p. 232 - 236.
Bovine spongiform encephalopathy - diagnosis - EU - goats - rapid tests - scrapie - sensitivity - surveillance
We report the diagnostic sensitivity of 3 EU-approved rapid tests (ELISAs; 1 from IDEXX and 2 from Bio-Rad) for the detection of transmissible spongiform encephalopathy diseases in goats. Ninety-eight goat brainstem samples were tested. All the rapid tests had 100% specificity and ≥80% sensitivity, with the IDEXX test significantly more sensitive than the 2 Bio-Rad tests. All tests detected 100% of samples from goats with clinical scrapie, but missed 8% (IDEXX) to 33% (Bio-Rad SG) of samples from preclinical goats. Importantly, only IDEXX picked up all samples from clinical bovine spongiform encephalopathy (BSE)-infected goats, whereas the other 2 rapid tests missed 15% (Bio-Rad SG) to 25% (Bio-Rad SAP). These results show that a fraction of preclinical scrapie infections are likely missed by EU surveillance, with sensitivity of detection strongly dependent on the choice of the rapid test. Moreover, a significant proportion of clinical BSE infections are underestimated by using either Bio-Rad test. Assuming that the same sensitivity on preclinical goats would also occur in BSE-infected goats, our data suggest that IDEXX is likely the most sensitive test for detecting preclinical field cases of BSE infection in goats, although with an 8% failure rate. These results raise some concerns about the reliability of current EU surveillance figures on BSE infection in goats.
Mapping Soil Properties of Africa at 250 m resolution: random forest significantly improve current predictions
Hengl, T. ; Heuvelink, G.B.M. ; Kempen, B. ; Leenaars, J.G.B. ; Walsh, M.G. ; Shepherd, K.D. ; Sila, A. ; Macmillan, R.A. ; Mendes de Jesus, J.S. ; Tamene, L. ; Tondoh, J.E. - \ 2015
PLoS One 10 (2015)6. - ISSN 1932-6203
continental-scale - maps - classification - surveillance - management - models - carbon - trees
80% of arable land in Africa has low soil fertility and suffers from physical soil problems. Additionally, significant amounts of nutrients are lost every year due to unsustainable soil management practices. This is partially the result of insufficient use of soil management knowledge. To help bridge the soil information gap in Africa, the Africa Soil Information Service (AfSIS) project was established in 2008. Over the period 2008–2014, the AfSIS project compiled two point data sets: the Africa Soil Profiles (legacy) database and the AfSIS Sentinel Site database. These data sets contain over 28 thousand sampling locations and represent the most comprehensive soil sample data sets of the African continent to date. Utilizing these point data sets in combination with a large number of covariates, we have generated a series of spatial predictions of soil properties relevant to the agricultural management—organic carbon, pH, sand, silt and clay fractions, bulk density, cation-exchange capacity, total nitrogen, exchangeable acidity, Al content and exchangeable bases (Ca, K, Mg, Na). We specifically investigate differences between two predictive approaches: random forests and linear regression. Results of 5-fold cross-validation demonstrate that the random forests algorithm consistently outperforms the linear regression algorithm, with average decreases of 15–75% in Root Mean Squared Error (RMSE) across soil properties and depths. Fitting and running random forests models takes an order of magnitude more time and the modelling success is sensitive to artifacts in the input data, but as long as quality-controlled point data are provided, an increase in soil mapping accuracy can be expected. Results also indicate that globally predicted soil classes (USDA Soil Taxonomy, especially Alfisols and Mollisols) help improve continental scale soil property mapping, and are among the most important predictors. This indicates a promising potential for transferring pedological knowledge from data rich countries to countries with limited soil data.
Antibody response and risk factors for seropositvity in backyard poultry following mass vaccination against highly pathogenic avian influenza and Newcastle disease in Indonesia
McLaws, M. ; Priyono, W. ; Bett, B. ; Al-Qamar, S. ; Claassen, I.J.T.M. ; Widiastuti, T. ; Poole, J. ; Schoonman, L. ; Jost, C. ; Mariner, J. - \ 2015
Epidemiology and Infection 143 (2015)8. - ISSN 0950-2688 - p. 1632 - 1642.
domestic poultry - h5n1 - ducks - surveillance - countries - efficacy - vaccines - vietnam - viruses - field
A large-scale mass vaccination campaign was carried out in Java, Indonesia in an attempt to control outbreaks of highly pathogenic avian influenza (HPAI) in backyard flocks and commercial smallholder poultry. Sero-monitoring was conducted in mass vaccination and control areas to assess the proportion of the target population with antibodies against HPAI and Newcastle disease (ND). There were four rounds of vaccination, and samples were collected after each round resulting in a total of 27 293 samples. Sampling was performed irrespective of vaccination status. In the mass vaccination areas, 20–45% of poultry sampled had a positive titre to H5 after each round of vaccination, compared to 2–3% in the control group. In the HPAI + ND vaccination group, 12–25% of the population had positive ND titres, compared to 5–13% in the areas without ND vaccination. The level of seropositivity varied by district, age of the bird, and species (ducks vs. chickens).
Schmallenberg Virus in Culicoides Biting Midges in the Netherlands in 2012
Elbers, A.R.W. ; Meiswinkel, R. ; Weezep, E. van; Kooi, E.A. ; Poel, W.H.M. van der - \ 2015
Transboundary and Emerging Diseases 62 (2015)3. - ISSN 1865-1674 - p. 339 - 342.
cattle - surveillance - bluetongue - infection - spp.
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).
Field evaluation of a novel synthetic odour blend and of the synergistic role of carbon dioxide for sampling host-seeking Aedes albopictus adults in Rome, Italy
Pombi, M. ; Jacobs, F.H.H. ; Verhulst, N.O. ; Caputo, B. ; Torre, A. della; Takken, W. - \ 2014
Parasites & Vectors 7 (2014). - ISSN 1756-3305 - 5 p.
bg-sentinel - diptera-culicidae - anopheles-gambiae - mosquitos - traps - malaria - urban - surveillance - europe
Background Despite the expanding worldwide distribution of Aedes albopictus and its increasing relevance as arboviral vector, current methods to collect adult specimens are not optimal. Improved approaches are thus needed to monitor their density and pathogen infections, and to establish baseline data for control interventions. A widely used device is the BG-Sentinel (BG-trap) which mostly targets host-seeking females attracted by release of CO2 and/or a synthetic odour blend (the BG lure). We compared the attractiveness of this blend to that of the Mbita (MB5) lure, a new synthetic blend of proven efficiency in attracting Afrotropical malaria vectors, and evaluated the additional effect of CO2 to the two odour baits. Findings We carried out 6x6 Latin square experiments in two Ae. albopictus-infested areas in Rome, baiting the BG-traps as follows: CO2, BG lure, MB5 lure, BG lure¿+¿CO2, MB5 lure¿+¿CO2, no bait. CO2 was derived from yeast-fermented sugar. Overall, 949 females and 816 males were collected. Baited traps collected significantly more females than unbaited ones. Traps baited with either lures in combination with CO2 were more effective than those baited with CO2 alone. No significant differences were observed in female captures between traps baited with any of the two lures, nor between the two lures, independently from the addition of CO2. The use of BG lure¿+¿CO2 significantly increased males catches compared to unbaited traps. Conclusions The results suggest a broad significance of the MB5 lure for sampling medically important mosquito species and highlight the high efficacy of the combination of lures¿+¿CO2 for female Ae. albopictus and of BG lure¿+¿CO2 for males, leading to consider CO2 as an essential additional cue for the sampling of this species.
The use of serosurveys following emergency vaccination, to recover the status of "foot-and-mouth disease free where vaccination is not practised"
Paton, D.J. ; Füssel, A.E. ; Vosloo, W. ; Dekker, A. ; Clerq, K. de - \ 2014
Vaccine 32 (2014)52. - ISSN 0264-410X - p. 7050 - 7056.
direct-contact challenge - virus transmission - fmd vaccines - nonstructural proteins - subclinical infection - reactive vaccination - carrier state - cattle - pigs - surveillance
To eliminate incursions of foot-and-mouth disease (FMD) quickly, a combination of measures, including emergency vaccination, can help block the spread of infection. For the earliest recovery of the FMD-free status for trade, without the slaughter of uninfected vaccinated animals, a serosurvey for antibodies to FMD virus non-structural proteins (NSP) must be used to substantiate absence of occult virus infections. Areas of doubt over requirements for post-vaccination serosurveillance and its feasibility include the required and achievable confidence, the amount of sampling necessary, and the appropriate responses to and consequences of different seropositive findings. This derives largely from uncertainty over the extent of localised pockets of virus infection that may remain within vaccinated populations and the circumstances that permit this. The question therefore remains whether tests are sufficiently sensitive and specific to detect and eliminate infected animals, without excessive culling of uninfected animals, before vaccinated animals mix with non-vaccinated livestock when movement restrictions are lifted. It is recommended to change the rationale for serosurveillance after emergency vaccination. Only when emergency vaccination is used in limited outbreaks is it possible to test and cull comprehensively, an approach compatible with a three-month minimum period to recover the FMD-free status. In other situations, where emergency vaccination is used, such as dealing with large outbreaks in animal-dense regions and where the onset of vaccination has been delayed, post-vaccination serosurveys should be targeted and focus on providing an assurance to detect higher levels of infection, in case of inadequate control measures. As this provides less assurance of absence of infection, the approach would be compatible with a six-month waiting period for free-status recovery and should be complemented by other methods to provide evidence that vaccination and control measures have been effectively implemented, as these are the best guarantee against continuing virus transmission.
Culicoides (Diptera: Ceratopogonidae) host preferences and biting rates in the Netherlands : comparing cattle, sheep and the black-light suction trap
Elbers, A.R.W. ; Meiswinkel, R. - \ 2014
Veterinary Parasitology 205 (2014)1-2. - ISSN 0304-4017 - p. 330 - 337.
new-york-state - midges diptera - molecular-identification - feeding patterns - bluetongue virus - attraction - spp. - onderstepoort - surveillance - bloodmeals
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 0.5min-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 0.1min-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. Copyright © 2014 Elsevier B.V. All rights reserved.
Risk factors for the presence of Aedes aegypti and Aedes albopictus in domestic water-holding containers in areas impacted by the Nam Theun 2 hydroelectric project, Laos
Hiscox, A.F. ; Kaye, A. ; Vongphayloth, K. ; Banks, I. ; Piffer, M. ; Khammanithong, P. ; Sananikhom, P. ; Kaul, S. ; Hill, N. ; Lindsay, S.W. ; Brey, P.T. - \ 2013
American Journal of Tropical Medicine and Hygiene 88 (2013)6. - ISSN 0002-9637 - p. 1070 - 1078.
dengue vector control - diptera-culicidae - singapore-city - mosquitos - l. - insecticide - thailand - vietnam - skuse - surveillance
We assessed risk factors for vectors of dengue and chikungunya viruses near a new hydroelectric project, Nam Theun 2, in Laos. Immature stages of Aedes aegypti were found only in sites within 40 km of the urban provincial capital, but Aedes albopictus was found throughout. Aedes aegypti pupae were most common in water storage jars (odds ratio [OR] = 4.72) and tires (OR = 2.99), and Ae. albopictus pupae were associated with tires in 2009 (OR = 10.87) and drums, tires, and jars in 2010 (drums OR = 3.05; tires OR = 3.45, jars OR = 6.59). Compared with water storage vessels, containers used for hygiene, cooking, and drinking were 80% less likely to harbor Ae. albopictus pupae in 2010 (OR = 0.20), and discarded waste was associated with a 3.64 increased odds of infestation. Vector control efforts should focus on source reduction of water storage containers, particularly concrete jars and tires.
Risk ranking of chemical hazards in food - A case study on antibiotics in the Netherlands
Asselt, E.D. van; Spiegel, M. van der; Noordam, M.Y. ; Pikkemaat, M.G. ; Fels-Klerx, H.J. van der - \ 2013
Food Research International 54 (2013)2. - ISSN 0963-9969 - p. 1636 - 1642.
surveillance - exposure - program
Part of risk based control is the prioritization of hazard-food combinations for monitoring food safety. The aim of the current study was to develop a method for risk ranking of chemical food safety hazards using a structured and transparent approach. The method established is semi-quantitative and uses scores on both severity and probability of the hazard. The method was applied in a case study on antibiotic residue monitoring in a variety of products in the Netherlands. Severity of the hazard was scored using the Acceptable Daily Intake (ADI) as well as a score on the severity of antimicrobial resistance. Probability of the hazard depended on the amount of product consumed and on the amount of antibiotics used in animals as well as evidence of residues found. Data were gathered using literature research and expert opinions. The method showed that antibiotics most relevant for monitoring were product specific. Overall, nitrofurans were amongst the most important antibiotics to be included in monitoring programs for the products studied: pork, beef, poultry, honey and shrimps. This was mainly due to the detection of residues in products imported from outside the EU. Oxytetracycline was another major important antibiotic for the products studied (both nationally produced and imported). The study showed that the method derived is capable of ranking antibiotic-food combinations and has potential for the application in other chemical hazard-food combinations
Actionable Knowledge and Strategic Decision-Making Related to Bio- and Agroterrorism Threats: Educational Needs on How to Build a Collaborative Early-Warning Culture
Martensson, P.A. ; Hedström, L. ; Sundelius, B. ; Skiby, J. ; Elbers, A.R.W. ; Knutsson, R. - \ 2013
Biosecurity and Bioterrorism: biodefense strategy, practice and science 11 (2013)Suppl. 1. - ISSN 1538-7135 - p. S46 - S54.
surveillance - diseases - bioterrorism
Current trends in biosecurity and cybersecurity include (1) the wide availability of technology and specialized knowledge that previously were available only to governments; (2) the global economic recession, which may increase the spread of radical non-state actors; and (3) recent US and EU commission reports that reflect concerns about non-state actors in asymmetric threats. The intersectoral and international nature of bioterrorism and agroterrorism threats requires collaboration across several sectors including intelligence, police, forensics, customs, and other law enforcement organizations who must work together with public and animal health organizations as well as environmental and social science organizations. This requires coordinated decision making among these organizations, based on actionable knowledge and information sharing. The risk of not sharing information among organizations compared to the benefit of sharing information can be considered in an “information sharing risk-benefit analysis” to prevent a terrorism incident from occurring and to build a rapid response capability. In the EU project AniBioThreat, early warning is the main topic in work package 3 (WP 3). A strategy has been generated based on an iterative approach to bring law enforcement agencies and human and animal health institutes together. Workshops and exercises have taken place during the first half of the project, and spin-off activities include new preparedness plans for institutes and the formation of a legal adviser network for decision making. In addition, a seminar on actionable knowledge was held in Stockholm, Sweden, in 2012, which identified the need to bring various agency cultures together to work on developing a resilient capability to identify early signs of bio- and agroterrorism threats. The seminar concluded that there are a number of challenges in building a collaborative culture, including developing an education program that supports collaboration and shared situational awareness.
Molecular Epidemiology of Bat Lyssaviruses in Europe
McElhinney, L.M. ; Marston, D.A. ; Leech, S. ; Freuling, C. ; Poel, W.H.M. van der; Echevarria, J. ; Vazquez-Moron, S. ; Horton, D.L. ; Müller, T. ; Fooks, A.R. - \ 2013
Zoonoses and Public Health 60 (2013)1. - ISSN 1863-1959 - p. 35 - 45.
daubentons bat - united-kingdom - rabies virus - eptesicus-isabellinus - myotis-daubentonii - type-2 - germany - identification - eblv-2 - surveillance
Bat rabies cases in Europe are principally attributed to two lyssaviruses, namely European bat lyssavirus type 1 (EBLV-1) and European bat lyssavirus type 2 (EBLV-2). Between 1977 and 2011, 961 cases of bat rabies were reported to Rabies Bulletin Europe, with the vast majority (>97%) being attributed to EBLV-1. There have been 25 suspected cases of EBLV-2, of which 22 have been confirmed. In addition, two single isolations of unique lyssaviruses from European insectivorous bats were reported in south-west Russia in 2002 (West Caucasian bat virus) and in Germany in 2010 (Bokeloh bat lyssavirus). In this review, we present phylogenetic analyses of the EBLV-1 and EBLV-2 using partial nucleoprotein (N) gene sequences. In particular, we have analysed all EBLV-2 cases for which viral sequences (N gene, 400 nucleotides) are available (n = 21). Oropharyngeal swabs collected from two healthy Myotis daubentonii during active surveillance programmes in Scotland and Switzerland also yielded viral RNA (EBLV-2). Despite the relatively low number of EBLV-2 cases, a surprisingly large amount of anomalous data has been published in the scientific literature and Genbank, which we have collated and clarified. For both viruses, geographical relationships are clearly defined on the phylogenetic analysis. Whilst there is no clear chronological clustering for either virus, there is some evidence for host specific relationships, particularly for EBLV-1 where more host variation has been observed. Further genomic regions must be studied, in particular for EBLV-1 isolates from Spain and the EBLV-2 isolates to provide support for the existence of sublineages.
Triazole fungicides and the selection of resistance to medical triazoles in the opportunistic mould Aspergillus fumigatus
Verweij, P.E. ; Kema, G.H.J. ; Zwaan, B.J. ; Melchers, W.J.G. - \ 2013
Pest Management Science 69 (2013)2. - ISSN 1526-498X - p. 165 - 170.
azole resistance - invasive aspergillosis - fungal disease - cyp51a gene - itraconazole - posaconazole - fluconazole - patient - surveillance - voriconazole
Azole resistance is an emerging problem in the opportunistic mould Aspergillus fumigatus. The triazoles are the most important agents for the management of Aspergillus diseases in humans. Selection for acquired resistance may occur in the hospital setting through exposure to high doses of azoles during azole therapy, but evidence is accumulating that A. fumigatus may become resistant to medical triazoles through environmental exposure to fungicides. The recovery of A. fumigatus isolates resistant to the medical triazoles from azole-naive patients as well as from the environment strongly indicates an environmental route of resistance selection. Molecule alignment studies have identified five fungicides that share a very similar molecule structure with the medical triazoles, and thus may have selected for mechanisms that confer resistance to both groups of compounds. It is important to explore further the presumed fungicide-driven route of resistance selection in order to implement effective preventive measures as the prevalence of azole resistance in A. fumigatus continues to increase and causes major challenges in the management of azole-resistant Aspergillus diseases
The post-Mao gazes: Chinese backpackers in Macau
Ong, C.E. ; Cros, H. du - \ 2012
Annals of Tourism Research 39 (2012)2. - ISSN 0160-7383 - p. 735 - 754.
budget travelers - tourism - power - surveillance - nationality - culture - drifter - state - road - self
This paper offers insights into backpacker tourism from the People’s Republic of China. Chinese backpackers are a distinctively post-Mao reform generation growing up at a time when China shifts from Mao Zedong’s socialist policies to Deng Xiaoping’s policy explorations with capitalism. Through distanced virtual ethnography of a leading internet forum, it has been discovered that the forum members’ post-Mao backpacker gazes appropriate the postcolonial spaces of Macau in ways that contradict existing backpacker ideals and media and academic portrayal and stereotyping of Chinese youths, particularly concerning gender role adoption and the exoticising of postcolonial leisurescape. Backpacking in Macau also reveals the communal and differentiated nature of the tourist gaze and Chinese mobilities
Underrecognized mildly symptomatic viremic dengue virus infections in rural Thai schools and villages
Yoon, I.K. ; Rothman, A.L. ; Tannitisupawong, D. ; Srikiatkhachorn, A. ; Jarman, R.G. ; Aldstadt, J. ; Nisalak, A. ; Mammen Jr., M.P. ; Thammapalo, S. ; Green, S. ; Libraty, D.H. ; Gibbons, R.V. ; Getis, A. ; Endy, T. ; Jones, J.W. ; Koenraadt, C.J.M. ; Morrison, A.C. ; Fansiri, T. ; Pimgate, C. ; Scott, T.W. - \ 2012
The Journal of Infectious Diseases 206 (2012)3. - ISSN 0022-1899 - p. 389 - 398.
kamphaeng phet - aedes-aegypti - transmission - children - epidemiology - blood - surveillance - inapparent - indonesia - patterns
BACKGROUND: The understanding of dengue virus (DENV) transmission dynamics and the clinical spectrum of infection are critical to informing surveillance and control measures. Geographic cluster studies can elucidate these features in greater detail than cohort studies alone. METHODS: A 4-year longitudinal cohort and geographic cluster study was undertaken in rural Thailand. Cohort children underwent pre-/postseason serology and active school absence-based surveillance to detect inapparent and symptomatic dengue. Cluster investigations were triggered by cohort dengue and non-dengue febrile illnesses (positive and negative clusters, respectively). RESULTS: The annual cohort incidence of symptomatic dengue ranged from 1.3% to 4.4%. DENV-4 predominated in the first 2 years, DENV-1 in the second 2 years. The inapparent-to-symptomatic infection ratio ranged from 1.1:1 to 2.9:1. Positive clusters had a 16.0% infection rate, negative clusters 1.1%. Of 119 infections in positive clusters, 59.7% were febrile, 20.2% were afebrile with other symptoms, and 20.2% were asymptomatic. Of 16 febrile children detected during cluster investigations who continued to attend school, 9 had detectable viremia. CONCLUSIONS: Dengue transmission risk was high near viremic children in both high- and low-incidence years. Inapparent infections in the cohort overestimated the rate of asymptomatic infections. Ambulatory children with mild febrile viremic infections could represent an important component of dengue transmission.
A quantitative risk assessment for bovine spongiform encephalopathy in Japan
Kadohira, M. ; Stevenson, M.A. ; Hogasen, H.R. ; Koeijer, A.A. de - \ 2012
Risk Analysis 32 (2012)12. - ISSN 0272-4332 - p. 2198 - 2208.
sensitivity analysis techniques - meat-and-bone - computer-models - bse epidemic - united-kingdom - cattle - dairy - prevalence - infection - surveillance
A predictive case-cohort model was applied to Japanese data to analyze the interaction between challenge and stability factors for bovine spongiform encephalopathy (BSE) for the period 1985–2020. BSE risk in cattle was estimated as the expected number of detectable cases per year. The model was comprised of a stochastic spreadsheet calculation model with the following inputs: (1) the origin and quantity of live cattle and meat and bone meal imported into Japan, (2) the age distribution of native cattle, and (3) the estimated annual basic reproduction ratio (R0) for BSE. The estimated probability of having zero detectable cases in Japan in 2015 was 0.90 (95% CI 0.83–0.95). The corresponding value for 2020 was 0.99 (95% CI 0.98–0.99). The model predicted that detectable cases may occur in Japan beyond 2015 because of the assumption that continued transmission was permitted to occur (albeit at a very low level) after the 2001 ban on the importation and domestic use of all processed animal proteins for the production of animal feed and for fertilizer. These results reinforce the need for animal health authorities to monitor the efficacy of control measures so that the future course of the BSE epidemic in Japan can be predicted with greater certainty
Quantifying antimicrobial resistance at veal calf farms
Bosman, A.B. ; Wagenaar, J.A. ; Stegeman, A. ; Vernooij, H. ; Mevius, D.J. - \ 2012
PLoS One 7 (2012)9. - ISSN 1932-6203 - 7 p.
fecal escherichia-coli - antibiotic-resistance - food animals - dairy-cows - pigs - samples - susceptibility - harmonization - surveillance - products
This study was performed to determine a sampling strategy to quantify the prevalence of antimicrobial resistance on veal calf farms, based on the variation in antimicrobial resistance within and between calves on five farms. Faecal samples from 50 healthy calves (10 calves/farm) were collected. From each individual sample and one pooled faecal sample per farm, 90 selected Escherichia coli isolates were tested for their resistance against 25 mg/L amoxicillin, 25 mg/L tetracycline, 0.5 mg/L cefotaxime, 0.125 mg/L ciprofloxacin and 8/152 mg/L trimethoprim/sulfamethoxazole (tmp/s) by replica plating. From each faecal sample another 10 selected E. coli isolates were tested for their resistance by broth microdilution as a reference. Logistic regression analysis was performed to compare the odds of testing an isolate resistant between both test methods (replica plating vs. broth microdilution) and to evaluate the effect of pooling faecal samples. Bootstrap analysis was used to investigate the precision of the estimated prevalence of resistance to each antimicrobial obtained by several simulated sampling strategies. Replica plating showed similar odds of E. coli isolates tested resistant compared to broth microdilution, except for ciprofloxacin (OR 0.29, p=0.05). Pooled samples showed in general lower odds of an isolate being resistant compared to individual samples, although these differences were not significant. Bootstrap analysis showed that within each antimicrobial the various compositions of a pooled sample provided consistent estimates for the mean proportion of resistant isolates. Sampling strategies should be based on the variation in resistance among isolates within faecal samples and between faecal samples, which may vary by antimicrobial. In our study, the optimal sampling strategy from the perspective of precision of the estimated levels of resistance and practicality consists of a pooled faecal sample from 20 individual animals, of which 90 isolates are tested for their susceptibility by replica plating.
Shrimp fisheries and aquaculture : making a living in the coastal frontier of Berau, Indonesia
Gunawan, B. - \ 2012
University. Promotor(en): Leontine Visser, co-promotor(en): A.S. Sidik. - [S.l. : S.n. - ISBN 9789461732866 - 233
garnalen - schaal- en schelpdierenvisserij - schaal- en schelpdierenteelt - aquacultuur - kustgebieden - vissers - middelen van bestaan - plattelandsontwikkeling - visgronden - hulpbronnenbeheer - toezicht - besluitvorming - levensomstandigheden - indonesië - shrimps - shellfish fisheries - shellfish culture - aquaculture - coastal areas - fishermen - livelihoods - rural development - fishing grounds - resource management - surveillance - decision making - living conditions - indonesia
Risk-based estimate of effect of foodborne diseases on public health, Greece
Gkogka, E. ; Reij, M.W. ; Havelaar, A.H. ; Zwietering, M.H. ; Gorris, L.G.M. - \ 2011
Emerging Infectious Diseases 17 (2011)9. - ISSN 1080-6040 - p. 1581 - 1590.
human brucellosis - united-states - burden - pathogens - illness - food - gastroenteritis - echinococcosis - surveillance - trends
The public health effects of illness caused by foodborne pathogens in Greece during 1996–2006 was quantified by using publicly available surveillance data, hospital statistics, and literature. Results were expressed as the incidence of different disease outcomes and as disability-adjusted life years (DALY), a health indicator combining illness and death estimates into a single metric. It has been estimated that each year ˜370,000 illnesses/million inhabitants are likely caused because of eating contaminated food; 900 of these illnesses are severe and 3 fatal, corresponding to 896 DALY/million inhabitants. Ill-defined intestinal infections accounted for the greatest part of reported cases and 27% of the DALY. Brucellosis, echinococcosis, salmonellosis, and toxoplasmosis were found to be the most common known causes of foodborne illnesses, being responsible for 70% of the DALY. Overall, the DALY metric provided a quantitative perspective on the impact of foodborne illness that may be useful for prioritizing food safety management targets.
Carbon dioxide baited trap catches do not correlate with human landing collections of Anopheles aquasalis in Suriname
Hiwat-van Laar, H. ; Andriessen, R. ; Rijk, M. de; Koenraadt, C.J.M. ; Takken, W. - \ 2011
Memorias Do Instituto Oswaldo Cruz 106 (2011)3. - ISSN 0074-0276 - p. 360 - 364.
light traps - malaria vectors - mosquitos - culicidae - diptera - tanzania - 1-octen-3-ol - gambiae - attractiveness - surveillance
Three types of carbon dioxide-baited traps, i.e., the Centers for Disease Control Miniature Light Trap without light, the BioGents (BG) Sentinel Mosquito Trap (BG-Sentinel) and the Mosquito Magnet® Liberty Plus were compared with human landing collections in their efficiency in collecting Anopheles (Nyssorhynchus) aquasalis mosquitoes. Of 13,549 total mosquitoes collected, 1,019 (7.52%) were An. aquasalis. Large numbers of Culex spp were also collected, in particular with the (BG-Sentinel). The majority of An. aquasalis (83.8%) were collected by the human landing collection (HLC). None of the trap catches correlated with HLC in the number of An. aquasalis captured over time. The high efficiency of the HLC method indicates that this malaria vector was anthropophilic at this site, especially as carbon dioxide was insufficiently attractive as stand-alone bait. Traps using carbon dioxide in combination with human odorants may provide better results.
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