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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Estimating host genetic effects on susceptibility and infectivity to infectious diseases and their contribution to response to selection
Anche, M.T. - \ 2016
Wageningen University. Promotor(en): Mart de Jong, co-promotor(en): Piter Bijma. - Wageningen : Wageningen University - ISBN 9789462577442 - 185 p.
livestock - hosts - genetic effects - susceptibility - infectivity - infectious diseases - breeding value - heritability - epidemics - vee - gastheren (dieren, mensen, planten) - genetische effecten - vatbaarheid - infectiviteit - infectieziekten - fokwaarde - epidemieën

Mahlet Teka Anche. (2016). Estimating host genetic effects on susceptibility and infectivity to infectious diseases and their contribution to response to selection. PhD thesis, Wageningen University, the Netherlands

Genetic approaches aiming to reduce the prevalence of an infection in a population usually focus on improving host susceptibility to an infection. The prevalence of an infection, however, is also affected by the infectivity of individuals. Studies reported that there exists among host (genetic/phenotypic) variation in susceptibility and infectivity to infectious diseases. The effect of host genetic variation in susceptibility and infectivity on the prevalence and risk of an infection is usually measured by the value of the basic reproduction ratio, R0. R0 is an important epidemiological parameter that determines the risk and prevalence of an infection. It has a threshold value of 1, where major disease outbreak can occur when R0 > 1 and the disease will die out when R0 < 1. Due to this threshold property, genetic improvements aiming to reduce the prevalence of an infection should focus on reducing R0 to a value below 1. The overall aim of this thesis was to develop methodologies that allow us to investigate the genetic effects of host susceptibility and infectivity on the prevalence of an infection, which is measured by the value of R0. Moreover, we also aim to investigating the effect of relatedness among groupmates on the utilization of among host genetic variation in susceptibility and infectivity so as to reduce the prevalence of infectious diseases. The theory of direct-indirect genetic effects and epidemiological concepts were combined to develop methodologies. In addition, a simulation study was performed to validate the methodologies developed and examine the effect of relatedness on the utilization of genetic variation in susceptibility and infectivity. It was shown that an individual’s genetic effect on its susceptibility and infectivity affect the prevalence of an infection and that an individual’s breeding value for R0 can be defined as a function of its own allele frequencies for susceptibility and infectivity and of population average susceptibility and infectivity. Moreover, simulation results show that, not only an individual’s infectivity but also an individual’s susceptibility represents an indirect genetic effect on the disease status of individuals and on the prevalence of an infection in a population. It was shown that having related groupmates allows breeders to utilize the genetic variation in susceptibility and infectivity, so as to reduce the prevalence of an infection.

Economic aspects of antiviral agents to control Classical Swine Fever epidemics
Bergevoet, R.H.M. ; Asseldonk, M.A.P.M. van; Backer, J.A. - \ 2012
The Hague : LEI, part of Wageningen UR (Report / LEI : Research area Agriculture &amp; entrepreneurship ) - ISBN 9789086156023
agrarische economie - antivirale middelen - classical swine fever virus - epidemieën - dierziekten - dierziektepreventie - economische aspecten - nederland - agricultural economics - antiviral agents - epidemics - animal diseases - animal disease prevention - economic aspects - netherlands
Outbreaks of contagious animal diseases such as Classical Swine Fever have detrimental effects on the livestock sector in an affected country as well as on society at large. The development of antiviral agents to control these epidemics can reduce the consequences of such outbreaks. The economic impact of applying these antiviral agents is until now unknown. In this report these consequences are investigated.
Vogelgriep ontrafeld : resultaten FES-AI onderzoeksprogramma
Luijkx, D.L.M. ; Scholtens, B. ; Nijland, H.R. - \ 2012
Lelystad : CVI - ISBN 9789461734907 - 62
aviaire influenza - aviaire influenzavirussen - vogels - pluimveehouderij - epidemieën - dierziektepreventie - ziektebestrijding - vaccinatie - diagnostiek - virologie - nederland - avian influenza - avian influenza viruses - birds - poultry farming - epidemics - animal disease prevention - disease control - vaccination - diagnostics - virology - netherlands
Vogelgriep en mensengriep zijn nauwe verwanten: beide worden meestal veroorzaakt door zogeheten Influenza-A-virussen. Zo'n griepvirus is een mini-kikkertje van hooguit honderd nanometer (0,0001 milimeter) doorsnede met eiwituitstulpingen aan de buitenkant. Daarmee klampt het virusbolletje zich vast aan de cellen van zijn gastheer. Die hechting heeft het nodig om de cel te infecteren en zichzelf daarna te kunnen vermenigvuldigen. Dit boekje heeft de vogelgriepuitbraak van 2003 in Nederland als startpunt. Welke dilemma's deden zich toen voor en welke bestrijdingsmogelijkheden waren er voorhanden? Vanwege de twijfels, vragen en onzekerheden werd het FES-AI onderzoeksprogramma in het leven geroepen. Het FES-AI programma is opgedeeld in 7 verschillende kennisvelden. Voor de samenstelling van dit boekje is gesproken met de onderzoekleiders, die het onderzoek vorm hebben gegeven.
Een gezonde discussie : morele en epidemiologische bijdragen voor dierziekten beleid
Stassen, E.N. ; Cohen, N.E. ; Bouma, A. ; Kupper, J.F.H. ; Meijboom, F.L.B. ; Brom, F.W.A. ; Stegeman, J.A. - \ 2011
[S.l.] : NWO [etc.] - 87
dierziektepreventie - dierziekten - epidemiologie - ethiek - mens-dier relaties - epidemieën - dierhouderij - animal disease prevention - animal diseases - epidemiology - ethics - human-animal relationships - epidemics - animal husbandry
Zorgvuldige bestrijding van zeer besmettelijke dierziekten
Jong, M.C.M. de; Hagenaars, T.H.J. - \ 2010
In: Over zorgvuldige veehouderij. Veel instrumenten, één concert / Eijsackers, H., Scholten, M., Wageningen : Wageningen UR (Essaybundel 2010 ) - ISBN 9789085858959 - p. 64 - 75.
dierziekten - diergezondheid - ziektebestrijding - epidemieën - diergeneeskunde - veehouderij - vaccinatie - animal diseases - animal health - disease control - epidemics - veterinary science - livestock farming - vaccination
In dit hoofdstuk wordt de bestrijding besproken van uitbraken van zeer besmettelijke dierziekten, in het jargon 'aangifteplichtige ziekten' genoemd. Daarbij bediscussiëren de auteurs ook wat voor deze ziekten bestrijdingstechnisch mogelijk is. Of en hoe we dierziekten bestrijden, zijn maatschappelijke keuzes. Die keuzemogelijkheden worden beperkt door de technische mogelijkheden en vooral door de kennis over de effecten van de te nemen bestrijdingsmaatregelen.
Considering animals : moral convictions concerning animals and judgement on the culling of healthy animals in animal disease epidemics
Cohen, N.E. - \ 2010
Wageningen University. Promotor(en): Elsbeth Stassen, co-promotor(en): F.W.A. Brom; J.A. Stegeman. - [S.l. : S.n. - ISBN 9789085857952 - 194
dierziekten - epidemieën - uitselecteren - ziektebestrijding - attitudes - dierhouderij - samenleving - nederland - dierethiek - moraal - vonnis - animal diseases - epidemics - culling - disease control - animal husbandry - society - netherlands - animal ethics - moral - judgement
Varkensgriep en Mexicaanse griep
Loeffen, W.L.A. - \ 2009
Veehouder en Dierenarts 23 (2009)4. - ISSN 1381-8007 - p. 16 - 18.
varkensinfluenzavirussen - virusziekten - influenza - epidemieën - ziekten - swine influenza viruses - viral diseases - epidemics - diseases
In april 2009 werden in Californië (VS) twee kinderen ziek met wat later een nieuw type griepvirus (influenza) zou blijken te zijn. Influenzaachtige verschijnselen waren in de maand daarvoor al opvallend veel waargenomen in Mexico. Deze bleken te zijn veroorzaakt door hetzelfde type griepvirus. Al snel werd deze influenzavariant bekend onder de naam Mexicaanse griep
On the political economy of plant disease epidemics : Capita selecta in historical epidemiology door J.C. Zadoks
Franke, A.C. - \ 2009
Gewasbescherming 40 (2009)5. - ISSN 0166-6495 - p. 245 - 245.
epidemieën - epidemiologie - plantenziekten - ziektegeval-definities - diagnose - geschiedenis - gewasbescherming - epidemics - epidemiology - plant diseases - case definitions - diagnosis - history - plant protection
Dit boek brengt een aantal casussen bijeen waarin de invloed van epidemieën van plantenziekten op de mens en de maatschappij nader bestudeerd wordt. ‘Political economy’ refereert hier naar een term uit de achttiende eeuw die tegenwoordig vooral gebruikt wordt voor de studie van economische en politieke veranderingen met behulp van diverse, interdisciplinaire en vaak onconventionele benaderingen
Flexible decision-making in crisis events : discovering real options in the control of foot-and-mouth disease epidemics
Ge, L. - \ 2008
Wageningen University. Promotor(en): Ruud Huirne, co-promotor(en): A.R. Kristensen; Monique Mourits. - [S.l.] : S.n. - ISBN 9789085049692 - 149
crises - mond- en klauwzeer - epidemieën - besluitvorming - ziektebestrijding - markov-processen - onzekerheid - dynamisch programmeren - bayesiaanse theorie - dynamische modellen - bedrijfseconomie - beslissingsondersteunende systemen - beslissingsmodellen - foot and mouth disease - epidemics - decision making - disease control - markov processes - uncertainty - dynamic programming - bayesian theory - dynamic models - business economics - decision support systems - decision models

Keywords
Crisis event, foot-and-mouth disease (FMD), epidemic control, real options, decision flexibility, multi-level hierarchic Markov process (MLHMP), uncertainty, decision-support framework, turning moment, dynamic programming, Bayesian forecasting, dynamic models, overreacting, underreacting

This research introduced the real options way of thinking into decision-making in crisis events like animal epidemics, with foot-and-mouth disease (FMD) as a case in point. A unique angle was taken to investigate decision flexibility in choosing optimal control strategies. The main objective was to develop a flexible decision-support framework which corresponds to practice and provides consistent treatment of ongoing uncertainty in controlling animal epidemics. Conceptualisation and operationalisation of decision flexibility were the two main focuses.
A decision analysis revealed the dynamic and sequential nature of decision- making in the control of animal epidemics. The importance of decision flexibility was attributed to the existence of uncertainty and linked decisions in the multi-stage decision process. Timing of control options and the possibility of learning were found to be essential in conceptualising decision flexibility. To operationalise decision flexibility, the main methodological approach was the integration of multi-level hierarchic Markov process (MLHMP) and Bayesian forecasting methods. Based on MLHMP and dynamic generalised linear models (DGLM), a new decision-support framework was developed to investigate the impact of uncertainty and the possibility of learning in choosing the optimal timing of control options over time. The framework paid special attention to the interdependency among strategic, tactical, and operational decisions in managing FMD epidemics. The decision-support framework was shown to be useful in contingency planning for future epidemics.
Addressing the decision flexibility in a dynamic decision process, real options analysis and MLHMP were found to be complementary in developing the flexible decision-support framework. Both required dynamic assessment of future epidemic development and control options. Towards empirical application of the decision-support framework, an integrated epidemic-economic modelling approach was described and illustrated with simulated epidemics. It was shown that, by including decision flexibility in the dynamic decision process of epidemic control, the new modelling approach enabled more realistic estimation of the costs of underreacting or overreacting than the traditional static approaches.

Multi-scale modeling of potato late blight epidemics
Skelsey, P. - \ 2008
Wageningen University. Promotor(en): Bert Holtslag, co-promotor(en): Wopke van der Werf; Geert Jan Kessel; Walter Rossing. - S.l. : S.n. - ISBN 9789085049418 - 257
phytophthora infestans - solanum tuberosum - epidemieën - ziektemodellen - sporenverspreiding - virulentie - epidemiologie - geïntegreerde plagenbestrijding - gastheer-pathogeen interacties - epidemics - disease models - spore dispersal - virulence - epidemiology - integrated pest management - host pathogen interactions
Keywords: Solanum, invasion, Gaussian plume model, functional connectivity, landscape design

Proper landscape-scale deployment of disease resistant genotypes of agricultural crop species could
make those crops less vulnerable to invasion by resistance breaking genotypes. Here we develop a
multi-scale, spatio-temporal model of the potato late blight pathosystem (Phytophthora infestans -
Solanum tuberosum) to investigate spatial strategies for the deployment of host resistance. The
model comprises a landscape generator, a potato late blight model, and a suite of aerobiological
models, including an atmospheric dispersion model. Spatial phenomena are solved using Fast Fourier
transforms.
Increasing the number of host genotypes caused the greatest reduction in epidemic extent,
followed by reduction of the proportion of potato in the landscape, lowering the clustering of host
fields, and reducing the size of host fields. Simulation results showed that spatial spread through
short-distance “island hopping” is not a prerequisite for P. infestans invasions, and it appeared not
possible to generate host free zones at the landscape level that were large enough to provide
worthwhile levels of resilience against disease invasion from one host area to another. Deployment
of host resistance in genotype mixtures had a large effect on disease invasion. A new functional
connectivity parameter, characterizing the probability of successful infection following spore
dispersal, proved to be useful in interpreting these results.
Variation in simulation results revealed the importance of using an atmospheric dispersion
model for dispersal, with large weather data sets, and many random landscape iterations. The
specific coincidence in time and space between weather conditions and the geographic locations of
source and target sites defined true landscape connectivity and determined model results regarding
inoculum exchange between fields.
Given the apparent capacity of P. infestans for long distance transport of viable inoculum, it can
be concluded that spatial resistance deployment strategies that center on the creation of spatial
barriers to disease at scales up to several kilometers may not be effective in mitigating invasions of
virulent pathogen strains. Strategies that induce finer-grained spatial and genotypic heterogeneities
in host populations are more limiting to epidemic spread. Genotype mixing was an effective option
for generating agricultural landscapes that are comparatively resilient to disease invasion.
Epidemiological analysis of the 2006 bluetongue virus serotype 8 epidemic in north-western Europe, A risk map for epidemic potential in the Netherlands
Koeijer, A. de; Hartemink, N. ; Boender, G.J. ; Elbers, A.R.W. ; Hesterbeek, J.A.P. - \ 2007
niet bekend : EFSA - 18
bluetonguevirus - epidemieën - epidemiologie - risicoschatting - virusziekten - ziekten overgebracht door vectoren - ziekteoverdracht - nederland - noordwest-europa - bluetongue virus - epidemics - epidemiology - risk assessment - viral diseases - vector-borne diseases - disease transmission - netherlands - northwestern europe
One of the most important aspects of vector-borne infections is the strong influence of weather and climate on the transmission. In response to the major epidemic of bluetongue in north western Europe between summer and autumn 2006, an interest in BTV control issues developed. In this context, a map indicating the spatial variation in BTV risk in the north western European region would be very useful. To this end, a new approach is used in which they combine a mathematical epidemiological model and a geographical information system to obtain a spatially explicit measure for the risk of an outbreak of BTV when the virus is introduced in an area
Epidemiologie van stengelaaltjes in bolgewassen
Os, G.J. van; Boer, F.A. de - \ 2006
Lisse : PPO Bloembollen - 35
ditylenchus dipsaci - bloembollen - quarantaine organismen - waardplanten - epidemieën - plantenziektebestrijding - nematoda - landbouwkundig onderzoek - ornamental bulbs - quarantine organisms - host plants - epidemics - plant disease control - agricultural research
Stengelaaltjes (Ditylenchus dipsaci) zijn quarantaineorganismen in de bollenteelt. Bij aantreffen van deze nematodensoort op bedrijven worden verstrekkende en verplichte maatregelen opgelegd voor de desbetreffende partijen bollen en bedrijven met grote financiële gevolgen. Met een speciale ontheffing van de PD kan grondontsmetting met metamnatrium+dazomet worden toegepast. Ook inundatie is inmiddels als maatregel toegestaan. Zonder sanering van het besmette perceel mag minimaal 6 jaar geen waardplantbloembolgewassen op besmette percelen geteeld worden. Er is grote behoefte aan kennis over de overleving en verspreiding van stengelaaltjes die meer inzicht kan bieden in de mogelijkheden voor alternatieve bestrijdingsmethoden. Hieraan is van 2002 t/m 2005 onderzoek verricht door PPO. Om meer inzicht te krijgen in de verdeling van stengelaaltjes in de bodem zijn na het rooien van zieke narcissen op verschillende diepten grondmonsters genomen en beoordeeld op de aanwezigheid van stengelaaltjes. Het merendeel van de stengelaaltjes kwam voor in de bovenlaag van 0-20 cm en lage aantallen stengelaaltjes waren te vinden op 20-40 cm en 40-60 cm. De werkingsdiepte van chemische grondontsmetting is maximaal 40 cm, maar veelal minder. Het is dan ook mogelijk dat een klein aantal aaltjes dieper in de grond de behandeling overleeft. In het onderzoek is nagegaan of stengelaaltjes uit narcis zich kunnen handhaven in nietwaardplantbolgewassen, zoals tulp, hyacint en krokus. De afsterving van aaltjes bij de teelt van een nietwaardgewas was vergelijkbaar met die bij braak. Twee jaar braak of een niet-waardbolgewas was echter onvoldoende voor een volledige afsterving van de stengelaaltjes. De voorlopige resultaten duiden erop dat het narcissenstengelaaltje zich niet kan vermeerderen of zich in stand kan houden op de nietwaardgewassen tulp, hyacint en krokus. Dit zou perspectieven kunnen bieden voor het differentiëren van het teeltverbod, afhankelijk van het aanwezige stengelaaltjesras. Voorwaarde is wel dat er een betrouwbare identificatiemethode is om de stengelaaltjesrassen eenduidig van elkaar te onderscheiden, en dat er sprake is van zuivere populaties van slechts één ras. Het onderzoek wordt in 2007 afgerond. Er is weinig bekend over mogelijke waardplanten voor bollenstengelaaltjes buiten de bolgewassen. Er is geïnventariseerd in hoeverre stengelaaltjes kunnen voorkomen op onkruiden. Grote aantallen narcissenstengelaaltjes zijn aangetroffen in diverse onkruiden die tussen zieke narcissen groeiden. Ook in onkruiden op besmette, braakliggende grond (na de teelt van zieke narcissen) zijn stengelaaltjes aangetroffen. Het is echter niet bekend hoe lang de aaltjes in onkruid overleven en of ze zich ook vermeerderen (waardplantstatus). Behalve in onkruiden zijn ook hoge aantallen stengelaaltjes aangetroffen in opslag van bladrammenas tussen zieke narcissen. Dit geeft te denken over de waardstatus van groenbemesters.
Outdoor ranging of poultry: a major risk factor for the introduction and development of high pathogenicity Avian Influenza
Koch, G. ; Elbers, A.R.W. - \ 2006
NJAS Wageningen Journal of Life Sciences 54 (2006)2. - ISSN 1573-5214 - p. 179 - 194.
pluimveehouderij - scharrelhouderij - infectieziekten - aviaire influenza A-virussen - wilde vogels - volksgezondheid - migratie - epidemiologie - epidemieën - fylogenie - bioveiligheid - poultry farming - free range husbandry - infectious diseases - avian influenza A viruses - wild birds - public health - migration - epidemiology - epidemics - phylogeny - biosafety - a viruses - british-columbia - sentinel ducks - wild ducks - hemagglutinin - waterfowl - outbreak - h7n7 - surveillance - minnesota
High-Pathogenicity Avian Influenza (HPAI) is an extremely infectious viral disease of poultry. Public health concerns were raised when six persons died in Hong Kong in 1997 after exposure to HPAI-infected poultry. Its danger became imminent in the recent HPAI epidemic in South-East Asia when the virus expanded its geographical range via parts of central Asia to Europe, Africa and the Middle East. Wild birds are frequently carriers of influenza A viruses. Nearly all Avian Influenza (AI) viruses isolated from wild birds are low-pathogenic and cause no clinical problems in these birds. Only after low-pathogenicity viruses are introduced in poultry, in particular in chickens and turkeys, high-pathogenicity mutants emerge after a variable length of time. Biosecurity is the first line of defence against an introduction of AI into commercial poultry flocks. Any conceivable contact between possibly contaminated animals, areas around poultry houses contaminated with faecal material from wild birds and contaminated abiotic vectors on the one hand and domestic poultry on the other must be avoided. In this paper we shall discuss the worldwide occurrence of HPAI outbreaks, the existence of AI virus infections in wild birds, and possible strategies to reduce the risk of the introduction of AI viruses into domestic poultry flocks, with special reference to free ranging
HIV/AIDS and human development in sub-Saharan Africa : impact mitigation through agricultural interventions : an overview and annotated bibliography
Müller, T.R. - \ 2005
Wageningen : Wageningen Academic Publishers (AWLAE series no. 3) - ISBN 9076998507 - 131
plattelandsontwikkeling - acquired immune deficiency syndrome - humaan immunodeficiëntievirussen - landbouwsector - epidemieën - volksgezondheid - interventie - afrika ten zuiden van de sahara - rural development - human immunodeficiency viruses - agricultural sector - epidemics - public health - intervention - africa south of sahara
This last part of the AWLAE series on HIV/AIDS and agriculture in sub-Saharan Africa focuses on the epidemic as a challenge to human development in general and rural development in particular. In the face of the impact of the epidemic as described in parts one and two of the series, the agricultural sector can potentially play an important role in mitigating some of its effects. Strategies for agricultural intervention are of particular importance in sub-Saharan Africa, given the fact that most of the countries hardest hit by the epidemic are heavily reliant on agriculture. Different agricultural sector based mitigation strategies are discussed. It is further argued, however, that such interventions need to be complemented by interventions from the health and other sectors, in particular by treatment regimes including access to antiretroviral drugs. The text is followed by an annotated bibliography.
Foot and Mouth Disease. New values, innovative research agendas and policies
Zijpp, A.J. van der; Braker, M.J.E. ; Eilers, C.H.A.M. ; Kieft, H. ; Vogelzang, T.A. ; Oosting, S.J. - \ 2004
Wageningen : Wageningen Academic Publishers (EAAP technical series no. 5) - ISBN 9076998272 - 69
mond- en klauwzeer - vee - infectieziekten - epidemieën - ziektebestrijding - crises - evaluatie - analyse - waarden - perceptie - landbouwbeleid - onderzoek - nederland - maatregelen - foot and mouth disease - livestock - infectious diseases - epidemics - disease control - evaluation - analysis - values - perception - agricultural policy - research - netherlands - measures
A Foot and Mouth Disease outbreak is not by definition similar to a Foot and Mouth Disease crisis. Why then did the 2001 outbreak result in a crisis situation in the Netherlands? It was not because nobody was prepared for it. The Ministry of Agriculture, Nature Management and Fisheries had a scenario in stock.The scenario was applied as intended. The scenario did what it was supposed to do: it prevented the spreading of the disease, it resulted in a relatively soon eradication of the disease and it minimised damage to agricultural exports. Nevertheless, the crisis was there. “Foot and Mouth Disease: new values, innovative research agenda’s and policies” reports a process in which individuals and groups involved in the crisis participated in a joint analysis of what caused the crisis, and in the making of a policy and research agenda. The conclusion was that ignorance of the societal function of animals and countryside was the cause of the crisis: the scenario focussed on Foot and Mouth Disease control in a production-oriented environment. In reality many people perceived that the scenario and its rigid application threatened nonproduction values such as the companion role of animals and the recreation function of the landscape. Inevitably a next outbreak of Foot and Mouth Disease will occur.However, research and policy makers should seriously take up this perception of animals and countryside to prevent an outbreak of becoming a deep crisis again.
De toekomst van de zeehond hangt af van ons handelen
Reijnders, P.J.H. ; Jansen, B. - \ 2002
Zoogdier 13 (2002)3. - ISSN 0925-1006 - p. 16 - 19.
phoca vitulina - zeehonden - zeehondenziektevirus - morbillivirus - dierziekten - virusziekten - populaties - populatie-ecologie - populatiedynamica - populatiedichtheid - mortaliteit - natuurlijke selectie - epidemieën - natuurbescherming - wildbescherming - dierverzorging - dierenbescherming - wadden - waddenzee - diergezondheid - ecologie - fauna - populatiebiologie - zeezoogdieren - seals - phocine distemper virus - animal diseases - viral diseases - populations - population ecology - population dynamics - population density - mortality - natural selection - epidemics - nature conservation - wildlife conservation - care of animals - animal protection - tidal flats - wadden sea
Omdat de zeehondenpopulatie in de Waddenzee opnieuw bedreigd wordt door het zeehondenvirus stelt zich de vraag of menselijk ingrijpen in de vorm van grootschalige opvang van zieke dieren gewenst is. Daarbij spelen diverse overwegingen en randvoorwaarden een rol: nationale en internationale wetgeving m.b.t. natuurbescherming en natuurbeheer, zorgplicht voortvloeiend uit de Welzijnswet, en ecologische aspecten. Omdat het behoud van de populatie als geheel voorop staat en er ecologische risico's verbonden zijn aan opvang en weer vrijlaten van individuele dieren, moet de opvang tot een maatschappelijk aanvaardbaar minimum beperkt blijven
Stap naar hechtere samenwerking tussen Nederland en Zuid-Afrika. Wageningse aio's op studiereis naar Zuid-Afrika
Gaag, M. van der; Lieshout, M. van; Melse, A. ; Olthof, M. ; Tiemersma, E. ; Vissers, M. - \ 2000
Voeding Nu 2 (2000)2. - ISSN 1389-7608 - p. 28 - 29.
voedselhygiëne - voedingstoestand - voedingsstoffentekorten - samenwerking - universitaire onderwijsprogramma's - universiteiten - praktijkonderwijs - onderzoekers - zuid-afrika - nederland - voedingsleer - gezondheidseducatie - gezondheidszorg - epidemieën - epidemiologie - wetenschappelijke medewerkers - intellectuelen - food hygiene - nutritional state - nutrient deficiencies - cooperation - college programs - universities - practical education - research workers - south africa - netherlands - nutrition knowledge - health education - health care - epidemics - epidemiology - academic workers - intellectuals
Het doel van de studiereis was om kennis uit te wisselen tussen de Nederlandse onderzoekers in opleiding en hun Zuid-Afrikaanse collegae, op het gebied van voeding, gezondheid en epidemiologie
De vreselijkste aller harpijen : pokkenepidemieen en pokkenbestrijding in Nederland in de achttiende en negentiende eeuw : een sociaal-historische en historisch-demografische studie
Rutten, W. - \ 1997
Agricultural University. Promotor(en): A.M. van der Woude. - Wageningen : LU - 559
pokken - epidemieën - epidemiologie - therapie - behandeling - cultuur - geschiedenis - nederland - cultuurgeschiedenis - beschaving - smallpox - epidemics - epidemiology - therapy - treatment - culture - history - netherlands - cultural history - civilization

This study examines the fight against smallpox in the Netherlands in the 18th and 19th centuries. Smallpox mortality dropped in an unprecedented way from about 1810, generating a substantial reduction in the urban child mortality rate. The impact of vaccination on the acceleration of the Dutch population growth since the early 19th century should be seen in relation to the fact that smallpox was of minor importance in smaller towns and rural areas long before preventive measures became effective. Experiments with cowpox started as early as 1799. Vaccination was successfully implemented in the first decade of the 19th century, and it became the single most important factor for the decrease of the incidence of smallpox. Setting aside annual fluctuations, vaccination rates (expressed as the number of vaccinations on people of all ages as a proportion of the total number of live-births) were, on average, above 50 % from the 1810s to the 1860s. Vaccination coverage was raised further to 70-80 % when it was made compulsory for children attending primary school in 1872 (Contagious Diseases Act). The geographical pattern of vaccination coverage is systematically examined, as are differences between religious denominations. Until the 1870s, the differences between regions in the uptake of vaccination were more striking than those between denominations. After 1872, these regional differences decreased and the religious differentials became more evident. Traditionally, antivaccination feeling was strong among strict Calvinists. This study also makes an assessment of the importance of vaccination for medicalization.

Assessment of vegetable, fruit, and antioxidant vitamin intake in cancer epidemiology
Ocké, M.C. - \ 1996
Agricultural University. Promotor(en): Daan Kromhout; W.A. van Staveren; H.B. Bueno de Mesquita. - S.l. : Ocke - ISBN 9789054855064 - 164
carcinoom - neoplasma's - epidemieën - epidemiologie - groenten - fruitgewassen - dieet - diëtetiek - carcinoma - neoplasms - epidemics - epidemiology - vegetables - fruit crops - diet - dietetics
<br/>Inverse associations are consistently observed in epidemiological studies on the relations between the consumption of vegetables and fruits and different types of cancer. The strength of these associations is, however, unknown amongst others because of measurement error in data on vegetable and fruit intake. The antioxidant (pro)vitamins β-carotene, vitamin C, and vitamin E, are three of many substances in vegetables and fruits which may be responsible for the anticarcinogenic effect. This thesis is focused on the problem of intake assessment of vegetables, fruits, and antioxidant (pro)vitamins.<p>In the first part of the thesis, two studies on the relationships between the consumption of vegetables, fruits, and antioxidant (pro)vitamins and the occurrence of cancer are described. In the Seven Countries Study intake of vitamin C was inversely related to stomach cancer mortality at ecological level. Subjects with low intakes of vegetables, fruits, and β-carotene that were stable over time experienced more than two-fold increased risks of lung cancer in the Zutphen Study than subjects with high stable intakes. A lack of information on the extent of measurement error in the dietary data in both studies hampered the correct interpretation of the results.<p>The second part of the thesis includes several studies on the estimation of measurement error in data on vegetable, fruit, and antioxidant (pro)vitamin intake and biochemical markers. In a study on the effects of frozen storage at -20°C it was shown that vitamin E concentrations in EDTA-plasma decreased dramatically between 6 and 12 months, whereas for β-carotene this took place after 1 year. The use of such plasma in nested case-control or case-cohort studies would result in highly attenuated odds ratios for β-carotene and vitamin E.<p>Reproducibility and relative validity for food group and nutrient intake assessed with an extensive semi-quantitative food frequency questionnaire was also investigated. The questionnaire seemed adequate for ranking subjects according to intake of most nutrients and food groups including fruits, but it did not yield such good results for vegetables, β-carotene, vitamin C for men, and vitamin E for women. The observed correlation coefficients between questionnaire and repeated 24-h recall data may be either over- or underestimates of the true validity coefficients, because of unknown error structure in both types of data. Validity coefficients estimated by a triangular comparison between questionnaire, 24-h recall, and biomarker measurements will probably be overestimates of true validity coefficients.<p>From these studies it is concluded that measurement error in assessing vegetable, fruit, and antioxidant (pro)vitamin intake may be large, which is a handicap for epidemiological studies. Further progress lies in improvement of dietary assessment methods, and probably even more in understanding error structures and the development of analytical methods to recognize and cope with those structures.
Homocysteine, B-vitamins and cardiovascular disease : epidemiologic evidence
Verhoef, P. - \ 1996
Agricultural University. Promotor(en): Frans Kok; M.J. Stampfer. - S.l. : Verhoef - ISBN 9789054855002 - 167
cystine - cysteïne - methionine - aminozuren - chemie - nicotinamide - vitamine b complex - riboflavine - pantoteenzuur - choline - myo-inositol - vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - epidemieën - epidemiologie - cysteine - amino acids - chemistry - vitamin b complex - riboflavin - pantothenic acid - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - epidemics - epidemiology
<strong><em>Background</em></strong> Cardiovascular disease constitutes a major public health problem in the Netherlands and other Western countries. Elevated plasma homocysteine has attracted growing interest as a "new" risk factor for cardiovascular disease. Homocysteine is formed from the essential amino acid methionine. Defective Homocysteine, metabolism may lead to elevation of plasma total homocysteine (tHcy). Genetic enzyme deficiencies or inadequate intake of vitamins B <sub><font size="-2">6</font></sub> , B <sub><font size="-2">12</font></sub> , and folate, all important cofactors in homocysteine metabolism, may result in elevation of tHcy. Accumulation of tHcy can possibly promote atherosclerotic or thrombotic processes.<p><em><strong>Methods</strong></em> The epidemiologic studies presented in the thesis, aimed to find additional evidence for the hypothesis that elevated plasma tHcy is an independent risk factor for cardiovascular disease. We addressed various disease endpoints, with data of prospective and retrospective studies, from Dutch, European, and US populations. The role of the B-vitamins and of a genetic enzyme defect, predisposing to high tHcy levels, were studied.<p><em><strong>Results</strong></em> Overall, in line with other findings, most of our studies showed that elevated tHcy is an independent risk factor for cardiovascular disease. Results indicated that the risk increased with rising levels of tHcy, with no threshold effect. The estimated average % increase in risk for 5 μmol/L (about 1 SD) increase in fasting tHcy varied between 20% and 60% in the various studies. In a large European case-control study, we found that elevated tHcy was a strong risk factor in women, both in pre- and postmenopausal women.<p>Folate concentrations in plasma or expressed per haematocrit, and dietary folate were found to be important determinants of plasma tHcy in several studies. In one of our studies, in concordance with findings of others, tHcy reached its nadir at a folate intake of 400 μg/day. Furthermore, we observed that homozygosity for a mutation in 5,10-methylenetetrahydrofolate reductase, in combination with low folate status, predisposed to particularly high tHcy levels, and may thereby increase risk of cardiovascular disease.<p><strong><em>Conclusions & implications</em></strong> Dietary folate intake of a large segment of the general population is lower than 400 μg/day, and tHcy may be generally increased. Several studies have already shown that elevated tHcy can be normalized by supplementation with folate, even at a dose of 650 μg/day. Thus, increased folate intake seems an important way to decrease tHcy in populations, thereby possibly reducing incidence of cardiovascular disease. Large-scale prevention trials are warranted to demonstrate the efficacy of tHcy-lowering, and the minimal folate intake required. At this moment, based on the available epidemiologic evidence, it is advisable to increase consumption of fruits and vegetables in the general population. Results from prevention trials will indicate whether additional measures, such as fortification of food or supplementation are justified as well.
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