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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Counts of bovine monocyte subsets prior to calving are predictive for postpartum occurrence of mastitis and metritis
Pomeroy, Brianna ; Sipka, Anja ; Hussen, Jamal ; Eger, Melanie ; Schukken, Ynte - \ 2017
medicine - cell biology - genetics - ecology - immunology - mathematical sciences - developmental biology - infectious diseases - computational biology
The heightened susceptibility to infectious diseases in postpartum dairy cows is often attributed to immune dysfunction associated with the transition period. However, the cell populations involved in this immune dysfunction and the dynamics between those populations are not well defined. Monocytes play a crucial role in governing initial immune response in bacterial infections. Bovine monocytes are subdivided in classical (CD14+/CD16−), intermediate (CD14+/CD16+) and non-classical monocytes (CD14−/CD16+) with distinct phenotypic and functional differences. This study investigated the relationship of monocyte subsets counts in blood at 42 and 14 days prior to expected calving date to occurrence of metritis and mastitis within 2 weeks postpartum. In the enrolled prospective cohort of 27 German Holstein cows, housed at the Institute of Animal Nutrition of the Friedrich-Loeffler-Institute Braunschweig, Germany, n = 13 developed metritis and/or mastitis postpartum. A multivariable logistic regression was used to analyze the relationship between prepartum cell counts of monocyte subsets and neutrophils with postpartum disease. Our model revealed that higher counts of the two CD14+ monocyte subsets were predictive of disease. In contrast, higher numbers of the CD14− monocyte subset were negatively associated with disease. Interestingly, the neutrophil count, a common hallmark for inflammatory response, was not associated with the outcome variable at either time point. The results indicate that the number and composition of monocyte subsets before calving are related to the susceptibility to infectious disease within 2 weeks postpartum. Furthermore the oppositional effect of CD14+ and CD14− subsets strengthens the hypothesis that these subsets have different functional roles in the inflammatory response in dairy cows.
Wat zijn de mogelijkheden om een leverbotinfectie van melkvee te voorkomen?
Neijenhuis, Francesca ; Verwer, Cynthia ; Verkaik, Jan - \ 2017
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 1029) - 65
leverbot - fascioliasis - melkvee - melkveehouderij - parasitosen - infectieziekten - dierlijke productie - dierenwelzijn - diergezondheid - biologische landbouw - liver flukes - dairy cattle - dairy farming - parasitoses - infectious diseases - animal production - animal welfare - animal health - organic farming
Infecties met leverbot zijn in toenemende mate een knelpunt in de diergezondheid van grazende (of vers gras gevoerde) herkauwers. Leverbotinfectie leidt tot ziekte met economische gevolgen en voor melkgevende dieren zijn geen anthelmintica vrij beschikbaar. In dit project is het leverbotinstrument ontwikkeld met als doel om veehouders inzicht en handelingsperspectief te geven ten aanzien van de leverbotsituatie op hun bedrijf. In dit rapport worden de resultaten weergegeven van het leverbotinstrument en een drietal preventieve maatregelen die zijn uitgeprobeerd.
Estimating host genetic effects on susceptibility and infectivity to infectious diseases and their contribution to response to selection
Anche, M.T. - \ 2016
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.

GD-directeur Ynte Schukken reageert op suggesties: 'geen specifieke zorgen over diergezondheid op grote bedrijven' : groei vraagt meer aandacht voor infectieziekten
Schukken, Ynte - \ 2016
dairy cattle - dairy farming - animal health - farm size - infectious diseases - animal disease prevention

Theoretisch is goed te verklaren dat infectieziekten vaker voorkomen als melkveebedrij ven groeien. Maar GD-directeur Ynte Schukken wil daarmee niet gezegd hebben dat besmettingen op grote bedrij ven voor meer problemen zouden zorgen

Breeding against infectious diseases in animals
Rashidi, H. - \ 2016
University. Promotor(en): Johan van Arendonk, co-promotor(en): Herman Mulder; P.K. Mathur. - Wageningen University - ISBN 9789462576452 - 179 p.
livestock - infectious diseases - animal breeding - selective breeding - disease resistance - tolerance - genetic variation - breeding value - genetic correlation - traits - genomics - animal genetics - vee - infectieziekten - dierveredeling - selectief fokken - ziekteresistentie - tolerantie - genetische variatie - fokwaarde - genetische correlatie - kenmerken - genomica - diergenetica

Infectious diseases in farm animals are of major concern because of animal welfare, production costs, and public health. Farms undergo huge economic losses due to infectious disease. The costs of infections in farm animals are mainly due to production losses, treatment of infected animals, and disease control strategies. Control strategies, however, are not always successful. Selective breeding for the animals that can mount a defence against infection could therefore be a promising approach. Defensive ability of an animal has two main mechanisms: resistance (ability to control the pathogen burden) and tolerance (ability to maintain performance when pathogen burden increases). When it is difficult to distinguish between resistance and tolerance, defensive ability is measured as resilience that is the ability to maintain performance during a disease outbreak regardless of pathogen burden. Studies have focused on the genetics of resistance and resilience with little known about the genetics of tolerance and its relationship with resistance and resilience. The objectives of this thesis were to: 1) estimate the genetic variation in resistance, tolerance, and resilience to infection in order to assess the amenability of these traits for selective breeding in farm animals, 2) estimate the genetic correlation between resistance, tolerance and resilience and 3) detect genomic regions associated with resistance, tolerance, and resilience.

In chapter 2, we studied the variation among sows in response to porcine reproductive and respiratory syndrome (PRRS). First a statistical method was developed to detect PRRS outbreaks based on reproduction records of sows. The method showed a high sensitivity (78%) for disease phases. Then the variation of sows in response to PRRS was quantified using 2 models on the traits number of piglets born alive (NBA) and number of piglets born dead (LOSS): 1) bivariate model considering the trait in healthy and disease phases as different traits, and 2) reaction norm model modelling the response of sows as a linear regression of the trait on herd-year-week estimates of NBA. Trait correlations between healthy and disease phases deviated from unity (0.57±0.13 – 0.87±0.18). The repeatabilities ranged from 0.07±0.027 to 0.16±0.005. The reaction norm model had higher predictive ability in disease phase compared to the bivariate model.

In chapter 3 we studied 1) the genetic variation in resistance and tolerance of sheep to gastrointestinal nematode infection and 2) the genetic correlation between resistance and tolerance. Sire models on faecal nematode egg count (FEC), IgA, and pepsinogen were used to study the genetic variation in resistance. Heritability for resistance traits ranged from 0.19±0.10 to 0.59±0.20. A random regression model was used to study the reaction norm of sheep body weight on FEC as an estimate of tolerance to nematode infection. We observed a significant genetic variance in tolerance (P<0.05). Finally a bivariate model was used to study the genetic correlation between resistance and tolerance. We observed a negative genetic correlation (-0.63±0.25) between resistance and tolerance.

In chapter 4, we studied the response to selection in resistance and tolerance when using estimated breeding values for resilience. We used Monte Carlo simulation to generate 100 half-sib families with known breeding values for resistance (pathogen burden) and tolerance. We used selection index theory to predict response to selection for resistance and tolerance: 1) when pathogen burden is known and selection is based on true breeding values for resistance and tolerance and 2) when pathogen burden is unknown and selection is based on estimated breeding values for resilience. Using EBV for resilience in absence of records for pathogen burden resulted in favourable responses in resistance and tolerance to infections, with more emphasis on tolerance than on resistance. However, more genetic gain in resistance and tolerance could be achieved when pathogen burden was known.

In chapter 5 we studied genomics regions associated with resistance, resilience, and tolerance to PRRS. Resistance was modelled as sire effect on area under the PRRS viremia curve up to 14 days post infection (AUC14). Resilience was modelled as sire effects on daily growth of pigs up to 28 days post infection (ADG28). Tolerance was modelled as the sire effect on the regression of ADG28 on AUC14. We identified a major genomics region on chromosome 4 associated with resistance and resilience to PRRS. We also identified genomics regions on chromosome 1 associated with tolerance to PRRS.

In the general discussion (chapter 6) I discussed: 1) response to infection as a special case of genotype by environment interaction, 2) random regression model as a statistical tool for studying response to disease, 3) advantages and requirements of random regression models, and 4) selective breeding of farm animals for resistance, tolerance, and resilience to infections. I concluded that random regression is a powerful approach to estimate response to infection in animals. If the adequate amount of data is available random regression model could estimate breeding values of animals more accurately compared to other models. I also concluded that before including resistance and tolerance into breeding programs, breeders should make sure about the added values of including these traits on genetic progress. Selective breeding for resilience could be a pragmatic approach to simultaneously improve resistance and tolerance.

'Nederland is een veterinair voorbeeldland'
Vermaas, M. ; Hellebrekers, L.J. - \ 2015
Boerderij 100 (2015)38. - ISSN 0006-5617 - p. 16 - 18.
dierziekten - diergezondheid - infectieziekten - onderzoek - zoönosen - volksgezondheid - animal diseases - animal health - infectious diseases - research - zoonoses - public health
Ludo Hellebrekers is sinds 1 juni directeur van het Centraal Veterinair Instituut. Goede samenwerking met alle ketenpartijen en kennisgebieden is volgens hem essentieel.
Foot-and-mouth disease virus : the role of infection routes and species differences in the transmission of FMDV
Bravo De Rueda Cabrera, C. - \ 2015
University. Promotor(en): Mart de Jong, co-promotor(en): Aldo Dekker; Phaedra Eble. - Wageningen : Wageningen University - ISBN 9789462573284 - 137
mond- en klauwzeervirus - mond- en klauwzeer - infectieziekten - ziekteoverdracht - ziektebestrijding - infectiebestrijding - soortverschillen - epidemiologie - diergeneeskunde - foot-and-mouth disease virus - foot and mouth disease - infectious diseases - disease transmission - disease control - infection control - species differences - epidemiology - veterinary science

ÁFoot-and-mouth disease is a contagious viral disease of cloven-hoofed animals (e.g. cattle, sheep, pigs) and can cause severe economic losses to the farm animal industries. The aim of this thesis was to quantify underlying mechanisms regarding transmission of FMDV. With data from past animal experiments we identified the factors which are associated with the amount of virus shed by infected animals and thus may be of importance for transmission of the virus. In an experimental study, the contribution of the environment on the transmission of FMDV was investigated by using a new mathematical model in which the contribution of the environment on transmission was incorporated. Roughly 44% of the transmission of FMDV occurred through the environment that was contaminated with se-excretions from FMDV infected animals. The role of the different species on the transmission of FMDV was investigated with a transmission study of FMDV between infected sheep and naïve cattle. Sheep were found to be less infectious than cattle but similarly susceptible. Using a so-called next-generation matrix, transmission of FMDV in mixed cattle-sheep populations (with different proportions of cattle and different proportions of vaccinated animals) was quantified and the effects of different vaccination strategies against FMDV were analysed. In mixed populations of cattle and sheep, transmission of FMDV is higher when more cattle are present. In populations with more than 14% cattle, targeting vaccination to cattle only can be sufficient to control FMDV.

The results of this thesis show that transmission of FMDV can occur via a contaminated environment, (without animal presence) and that sheep seem to play a limited role in the transmission of FMDV. These results can be used to improve the control measures to prevent and control FMDV in different animal populations.

Dierenlab beschermt mensen
Sikkema, A. ; Bianchi, A.T.J. - \ 2015
WageningenWorld (2015)1. - ISSN 2210-7908 - p. 24 - 27.
dierziekten - infectieziekten - zoönosen - virusziekten - onderzoek - diergezondheid - vaccins - aviaire influenza - q-koorts - animal diseases - infectious diseases - zoonoses - viral diseases - research - animal health - vaccines - avian influenza - q fever
Nederland krijgt steeds meer te maken met besmettelijke dierziektes die ook mensen ziek kunnen maken, zoals vogelgriep. Om daar goed onderzoek naar te doen is een lab gebouwd waarin levende, besmette landbouwhuisdieren gehouden worden. Geen virus kan eruit ontsnappen. ‘Zelfs het DNA wordt vernietigd.’
Interview Professor Joost van Neerven over onderzoek naar vermindering van allergieën door gerichte voeding en aanvullende micronutriënten
Neerven, R.J.J. van - \ 2014
Wageningen : Wageningen UR
voeding en gezondheid - voedselonderzoek - immuunsysteem - ziektepreventie - infectieziekten - allergieën - gezondheidsbevordering - nutrition and health - food research - immune system - disease prevention - infectious diseases - allergies - health promotion
Met gerichte voeding en aanvullende micronutriënten kan de weerstand tegen infecties in de luchtwegen, tegen allergieën, en tegen ontstekingen worden vergroot. Dat is van groot belang voor kinderen onder de 5 jaar en voor 65-plussers, die het vaakst door deze aandoeningen worden geplaagd. De weerstand in weefsels die bedekt zijn met een slijmvlies in het gebied van de mond, keel, en neus is nog nauwelijks onderzocht. Toch kan dit onderzoek veel opleveren, vindt prof. Joost van Neerven.
Mucosal immunity : barriers, bugs, and balance
Neerven, R.J.J. van - \ 2014
Wageningen : Wageningen University, Wageningen UR - ISBN 9789462571952 - 24
immuniteit - immuniteitsreactie - immuunsysteem - immunologie - infectieziekten - ontsteking - orale vaccinatie - voeding - immunity - immune response - immune system - immunology - infectious diseases - inflammation - oral vaccination - nutrition
Mechanisms underlying disease transmission between spatially separated animals
Bunnik, B.A.D. van - \ 2014
University. Promotor(en): Mart de Jong, co-promotor(en): Thomas Hagenaars; Gonnie Nodelijk. - Wageningen : Wageningen University - ISBN 9789461739537 - 150
dieren - vleeskuikens - infectieziekten - ziekteoverdracht - gastheren (dieren, mensen, planten) - wiskundige modellen - epidemiologie - diergeneeskunde - animals - broilers - infectious diseases - disease transmission - hosts - mathematical models - epidemiology - veterinary science

Transmission of infections between spatially separated hosts is a common problem, not only during major outbreaks of livestock diseases, but also in many other settings such as the transmission of infectious diseases between plants and crops or in healthcare settings. During the last major epidemics of livestock diseases in the Netherlands and abroad, disease transmission events occurred despite movement bans and other (bio-)security measures, implying that indirect transmission plays a major role. A better understanding of indirect transmission is necessary to put in place evidence based bio-security measures against neighbourhood (indirect) transmission. To gain more insight in the mechanisms underlying indirect transmission a series of experimental studies combined with mathematical modelling were conducted of which the results are presented in this thesis. First the effect of acidification of drinking water on the transmission parameters of direct and indirect transmission of Campylobacter jejuni (C. jejuni) between broilers was studied. It was shown that acidified drinking water has an effect on indirect transmission but not on direct transmission of C. jejuni between broilers. The sender and receiver sub-process of indirect transmission was then studied in more detail and it was shown that a significant negative interaction effect between acidification of the sender and receiver sub-processes exists, indicating that there is no additional effect of acidification of the drinking water on both sides of the transmission process compared to acidified drinking water only on one side. To study the transport of the pathogen in the environment in more detail, a series of indirect transmission experiments was carried out and a model framework was developed to study indirect transmission between spatially separated hosts. These studies showed that indirect transmission of C. jejuni between broilers is best described by a multistage environmental route from sending to receiving animal, suggesting that indirect transmission occurs through progressive (but slow) contamination of the environment surrounding the source. Indirect transmission experiments where repeated with both C. jejuni and Escherichia coli and the results showed that for C. jejuni it takes much longer for the first effective (viable) bacterium to cross the small distance of approximately 75 cm than it does for Escherichia coli. A new modelling approach to study indirect transmission was developed guided by these indirect transmission experiments. This model is capable of accurately describing the pathogen dispersal process by a diffusive transport mechanism which includes pathogen mortality. Lastly, a range of dose-response models were compared and tested how well these fitted to the data from a dose-response experiment. Here it was shown that for interpolation purposes two relatively simple models are best capable of describing the data from the dose-response experiment. For extrapolation purposes, however, it was shown that from the models that were studied a model that abides by the independent action hypothesis is best.

Lokschapen vangen teken in het bos
Sikkema, A. ; Wieren, S.E. van - \ 2014
Wageningen UR/Stichting voor Duurzame Ontwikkeling
schapen - gastheer parasiet relaties - vangmethoden - lokken - natuurgebieden - borrelia burgdorferi - humane ziekten - lyme-ziekte - infectieziekten - insecticiden - experimenten - wetenschappelijk onderzoek - bosecologie - sheep - host parasite relationships - trapping - baiting - natural areas - human diseases - lyme disease - infectious diseases - insecticides - experiments - scientific research - forest ecology
De Wageningse onderzoeker Sip van Wieren wil lokschapen inzetten om teken weg te vangen in natuurgebieden. Op die manier kunnen schaapskuddes er voor zorgen dat mensen prettig kunnen recreëren in het bos.
Population genetics and disease ecology of European wild boar
Goedbloed, D.J. - \ 2013
University. Promotor(en): Herbert Prins; Ron Ydenberg, co-promotor(en): Pim van Hooft. - S.l. : s.n. - ISBN 9789461737236 - 123
wilde varkens - sus scrofa - infectieziekten - populatiegenetica - ecologie - mycoplasma hyopneumoniae - varkenscircovirus-1 - ziekteoverdracht - fauna - noordwest-europa - wild pigs - infectious diseases - population genetics - ecology - porcine circovirus-1 - disease transmission - northwestern europe
Welke factoren beïnvloeden de frequentie van de ziekten in wilde populaties? Het promotieonderzoek van Daniel Goedbloed beoordeelde de invloed van demografische, genetische en omgevingsfactoren op de frequentie van twee infectieziekten in Noordwest-Europese wilde zwijnen populaties.
Onderzoek naar de oorzaak van 'zwarte vaten in radijs'
Ludeking, D.J.W. ; Hamelink, R. ; Hofland-Zijlstra, J.D. ; Wensveen, W. van - \ 2013
Bleiswijk : Wageningen UR Glastuinbouw (Rapporten WUR GTB 1241) - 38
radijsjes - raphanus sativus - symptomen - infectieziekten - verkleuring - vaatbundels - stenotrophomonas - glastuinbouw - glasgroenten - nederland - radishes - symptoms - infectious diseases - discoloration - vascular bundles - greenhouse horticulture - greenhouse vegetables - netherlands
Op één Nederlands radijsbedrijf treedt vanaf de herfst van 2007 een verschijnsel op, waarbij radijsknollen bruine tot zwarte vaatbundels vertonen. De radijsplantjes blijven veelal achter in groei of gaan dood. Uitwendig is de verkleuring niet altijd waarneembaar, waardoor deze knollen toch in het handelskanaal terecht kunnen komen. Sinds het voorjaar van 2008 is het verschijnsel ook op een ander bedrijf opgetreden. Op de betreffende bedrijven breidt het verschijnsel zich elk jaar uit en leidt tot veel schade in het winterhalfjaar. Een bekende ziekteverwekker is in voorgaande onderzoeken niet geïsoleerd, daarom is er in dit onderzoek verder gezocht om een onbekende ziekteverwekker te kunnen identificeren. Gedurende dit onderzoek is er vastgesteld dat de ziekte overdraagbaar is via grond en wordt veroorzaakt door de bacterie Stenotrophomonas spp. De bacterie is geïsoleerd uit geïnfecteerde knollen, er is een moleculaire analyse gemaakt van de isolaten en de postulaten van Koch zijn toegepast. Op basis van de analyse en het terug toetsen van het pathogeen kan worden geconcludeerd dat Stenotrophomonas spp. verantwoordelijk is voor de symptomen in het gewas.
Economic evaluation of FMD management options: implications for science and policy
Bergevoet, Ron - \ 2012
livestock farming - foot and mouth disease - infectious diseases - disease control - vaccination - economic impact - market economics - exports - losses - european union
Het Centraal Veterinair Instituut versterkt het onderzoek naar opkomende zoönosen
Poel, W.H.M. van der - \ 2012
Tijdschrift voor Diergeneeskunde 137 (2012)12. - ISSN 0040-7453 - p. 796 - 802.
zoönosen - dierziektepreventie - ziektebestrijding - infectieziekten - volksgezondheid - onderzoek - zoonoses - animal disease prevention - disease control - infectious diseases - public health - research - toxoplasma-gondii infection - avian influenza-virus - valley fever virus - west-nile-virus - streptococcus-suis - epidemiology - pathogenesis - netherlands - responses
Een zoönose is een infectieziekte die overgedragen kan worden van gewervelde dieren naar mensen of omgekeerd. Ruim 60 procent van de ziekteverwekkers bij mensen heeft een zoönotisch karakter. Het verkleinen van het risico van zoönosen voor de mens is één van de taken van het CVI. Samen met diverse partners richt het CVI zich op het vroegtijdig opsporen van deze ziekteverwekkers in het dierlijk reservoir en op het ontwikkelen van bestrijdingsmethoden. Het CVI is referentiecentrum voor aangifteplichtige dierziekten inclusief zoönosen en voert onderzoeksprojecten uit op het gebied van dierziektebestrijding voor zowel de overheid als in opdracht van externe partijen en in (inter)nationale samenwerkingsverbanden. Onderzoek aan zoönosen is daar een belangrijk onderdeel van. Ten behoeve van een betere preventie, opsporing en bestrijding van zoönosen wil het CVI het onderzoek naar opkomende zoönosen versterken. Een aantal voorbeelden van zoönosen waar het CVI aan werkt, wordt kort besproken.
Zoönosen : uit de ziekenboeg
Haenen, O.L.M. ; Beurden, S.J. van; Engelsma, M.Y. - \ 2012
Aquacultuur 27 (2012)1. - ISSN 1382-2764 - p. 24 - 28.
zoönosen - volksgezondheid - aquacultuur - kweekvis - infectieziekten - bedrijfshygiëne - zoonoses - public health - aquaculture - farmed fish - infectious diseases - industrial hygiene
Zoönosen zijn infectieziekten die overdraagbaar van dier op mens, zowel vanuit koudbloedige als warmbloedige dieren Ook bij contacten met aquacultuur- en visserijdieren is er een klein risico voor de mens op het oplopen van een ziekte. In de Nederlandse aquacultuur komen af en toe zoönotische bacteriën voor, die contactzoönose kunnen veroorzaken. Met voldoende hygiëne op aquacultuurbedrijven ontwikkelen deze bacteriën zich meestal niet tot een zoönose. Toch is het belangrijk, dat men op de hoogte is van risico's en mee helpt aan een goede diagnose van een aquatische zoönose, omdat deze in eerste instantie door de huisarts vaak niet als zodanig herkend wordt.
The relation between farming practices, ecosystem, and white spot in syndrome virus (WSSV) disease outbreaks in penaeus monodon farms in the Philippines
Tendencia Alapide, E. - \ 2012
University. Promotor(en): Johan Verreth, co-promotor(en): Roel Bosma; J.H. Primavera. - S.l. : s.n. - ISBN 9789461733702 - 135
garnalen - witte-vlekken-syndroom-virus - garnalenteelt - uitbraken (ziekten) - epidemiologie - infectieziekten - dierziektepreventie - aquatische ecosystemen - fysicochemische eigenschappen - mangroves - filippijnen - shrimps - white spot syndrome virus - shrimp culture - outbreaks - epidemiology - infectious diseases - animal disease prevention - aquatic ecosystems - physicochemical properties - philippines

The white spot syndrome virus (WSSV) affecting shrimp aquaculture in most producing countries has caused huge economic losses resulting in bankruptcy to both large and small farmers. Studies done on WSSV epidemiology were mostly tank-based and on species other than Penaeus monodon. There is a need to investigate WSSV epidemiology in P. monodon in on-farm situations, thus including both risk and protective factors. This thesis aimed to generate knowledge that can improve prevention against WSSV in shrimp culture through better farm husbandry by studying the epidemiology of WSSV in on-farm situations. To achieve this goal data from cross-sectional and case studies were analysed to identify on-farm WSSV risk and protective factors, and longitudinal studies were done to assess factors affecting water quality and causing WSSV infection to result in an outbreak.

The thesis identified the following WSSV risk factors related to the physico-chemical parameters of the water: low and fluctuating temperature, low and fluctuating salinity, and pH fluctuation. The risk of high temperature and high salinity for an outbreak of WSV disease may be related to fluctuations in these two parameters. Risk factors related to farm husbandry techniques were feeding with molluscs, sludge removal and its deposition on the dike, sharing water source with other farms and having the same receiving and intake water. Identified WSSV protective factors were high mangrove to pond area ratio, feeding with natural food or phytoplankton, and higher percentage of beneficial bacteria like the yellow colonies that grow on thiosulphate citrate bilesalt sucrose agar, a Vibrio selective medium.

Results of the longitudinal studies demonstrated that WSSV infection may not result in outbreaks in greenwater pond and in ponds with mangroves in the receiving environment. Our results did not provide explanations why the WSSV infection did not result in an outbreak in farms with mangroves in the receiving environment. In greenwater ponds, this was attributed to the better water and soil quality, higher plankton count, and higher heterotrophic bacterial count.

Infectierisico’s van de veehouderij voor omwonenden
Maassen, C.B.M. ; Duijkeren, E. van; Duynhoven, Y.T.H.P. van; Dusseldorp, A. ; Geenen, P. ; Koeijer, A.A. de; Koopmans, M.P.G. ; Loos, F. ; Jacobs-Reitsma, W.F. ; Jonge, M. de; Giessen, A.W. van de - \ 2012
Bilthoven : RIVM - 65
veehouderij - zoönosen - q-koorts - volksgezondheid - infectieziekten - livestock farming - zoonoses - q fever - public health - infectious diseases
Momenteel kunnen er geen wetenschappelijk onderbouwde uitspraken worden gedaan over het infectierisico van omwonenden van veehouderijen, met uitzondering van Q-koorts. Het is aangetoond dat omwonenden van melkgeitenbedrijven met Q-koorts, een verhoogd risico hebben om deze infectieziekte te krijgen. Voor de overige zoönosen (infectieziekten die van dier op mens worden overgedragen) zijn onvoldoende gegevens beschikbaar over het risico in relatie tot de afstand tot veehouderijen, het bedrijfstype en de bedrijfsgrootte. Wel is bekend dat veehouders, medewerkers op veehouderijen en dierenartsen een verhoogd risico hebben om bepaalde zoönosen op te lopen. Direct contact met dieren is daarbij vaak een risicofactor.
Vaccins beschermen dier én mens
Rijsman, V.M.C. - \ 2012
Kennis Online 9 (2012)april. - p. 19 - 19.
infectieziekten - zoönosen - diergezondheid - volksgezondheid - dierziektepreventie - vaccins - infectious diseases - zoonoses - animal health - public health - animal disease prevention - vaccines
Het bedrijf MSD Animal Health werkt met onderzoekers van Wageningen UR, het RIVM en de Universiteit Utrecht aan een betere bestrijding van infectieziekten die van dier op mens kunnen overslaan. 'We kunnen nu enkele producten ontwikkelen die mogelijk nooit commercieel aantrekkelijk zullen zijn, maar maatschappelijk wel relevant zijn.'
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