Rabies in Ethiopia: modelling the burden and the effectiveness of control
Beyene, Tariku Jibat - \ 2017
Wageningen University. Promotor(en): H. Hogeveen, co-promotor(en): M.C.M. Mourits. - Wageningen : Wageningen University - ISBN 9789463432177 - 194
cattle - dogs - rabies - farmers - cattle farming - vaccination - business economics - cost effectiveness analysis - ethiopia - east africa - rundvee - honden - hondsdolheid - boeren - rundveeteelt - vaccinatie - bedrijfseconomie - cost effective analysis - ethiopië - oost-afrika
Rabies claims the lives of more than 24,000 people in Africa annually, but efforts to control the disease are still lacking, particularly in sub-Saharan Africa such as Ethiopia. The overall objective of this study was to support the design of an appropriate cost-effective rabies control policy in Ethiopia by providing insights in the health burden of the disease and its economic impacts, as well as an understanding of the relationship between intervention levels, implementation costs and potential returns.
As most human rabies cases result from the bite of domestic dogs, the disease can be eliminated by mass canine rabies vaccination. An extensive literature review on mass canine vaccination programs in Africa indicated that most dogs in Africa are owned and therefore accessible for vaccination, but vaccination coverages strongly depend on the implemented cost schemes. Canine vaccination in Ethiopia is voluntarily based, i.e. “owner-charged”, resulting in one of the lowest coverages in the world.
To assess the current burden of rabies in Ethiopia a retrospective study was conducted by collecting data on human rabies exposure over the period of one year through extensive bite case searching in three representative districts of Ethiopia. Extrapolation of the results to national level indicated an annual average of 3,000 human deaths and 97,000 rabies-exposed persons treated at an average costs of 21 USD per case, causing 2 million USD on treatment costs per year and a health loss of about 93,000 DALYs. About 77% of the exposure cases visited a health centre, while only 57% received sufficient doses of post exposure treatment. Important factors that influenced victim’s medical treatment seeking behaviour were ownership status of the biting dog, severity of the bite, body part bitten, monthly spending and distance to the nearest health centre whereas the likelihood of receiving sufficient doses of treatment were determined by monthly spending and distance to health centre. The district in which victims lived appeared to have a relevant influence on the likelihood of seeking medical treatment but not on the likelihood of treatment compliance. By means of a structured questionnaire administered to cattle-owning households the economic impact of rabies in livestock was assessed. Herd-level incidence rates appeared higher in the mixed crop-livestock system (21%) than in the pastoral system (11%). Average economic losses per herd due to rabies were estimated at 49 USD per year for the mixed-crop livestock system, and at 52 USD per year for the pastoral system.
In light of policy support for rabies control, an evaluation of the cost-effectiveness of control strategies was performed by the use of a dynamic epidemiological model coupled with an economic analysis to predict the human health impact and economic benefit (reducing human treatment costs and livestock rabies-related losses) across a range of vaccination scenarios. Human exposures, human deaths, and rabies-related livestock losses decreased monotonically with increasing vaccination coverage. In the evaluated urban and rural districts, 50% coverage was identified as most likely scenario to provide the greatest net health benefits at the WHO-recommended willingness-to-pay threshold over a time frame of 10 years. The additional economic benefit from rabies control in livestock justified the additional costs of vaccination campaigns with higher coverages than would have been efficient from a strict human health perspective, highlighting the importance of applying a broad perspective with regard to the evaluation of vaccination benefits.
Farmers’ willingness to invest in livestock disease control: the case of voluntary vaccination against bluetongue
Sok, Jaap - \ 2017
Wageningen University. Promotor(en): A.G.J.M. Oude Lansink; H. Hogeveen, co-promotor(en): A.R.W. Elbers. - Wageningen : Wageningen University - ISBN 9789463437059 - 214
business economics - farmers - livestock - vaccination - bluetongue virus - animal diseases - animal disease prevention - netherlands - bedrijfseconomie - boeren - vee - vaccinatie - bluetonguevirus - dierziekten - dierziektepreventie - nederland
Animal health authorities in the European Union nowadays consider voluntary approaches based on a neoliberal model of cost and responsibility sharing as a tool for controlling livestock diseases. Policy makers aim for policies that are soft and optional, and use insights from behavioural economics and social psychology. Voluntary approaches are flexible in terms of legislation and can be effective at lower costs, provided that farmers are willing to participate. In 2008, the Dutch animal health authorities used a voluntary vaccination approach to control an emerging bluetongue epidemic that started end of 2006. Nearly 60,000 holdings with ruminants were already affected by the end of 2007 and experts indicated that transmission could only be stopped through mass vaccination. Farmers were motivated to participate by informational and financial, incentive-based policy instruments.
Economic theory predicts that farmers underinvest in private disease control measures in the presence of externalities. These studies, however, assume farmers only consider the private economic motives and that they only can be extrinsically motivated via (monetary) incentives. If the willingness to invest in livestock disease control is also driven by intrinsic and social motives, this could imply that not only financial compensation, but a mix of policy instruments is needed to make voluntary approaches work.
The overarching research objective of this thesis was to assess the key determinants of farmers’ willingness to vaccinate against bluetongue and study the impact of different policy designs on the effectiveness of voluntary vaccination approaches to bluetongue disease control.
A three-stage research approach was conducted. Two models of decision making, one from economics and one from social psychology, were first applied to the case study to obtain a solid understanding of important perceptions and motivations that farmers have to invest in livestock disease control. These motivations (sometimes incentives) and perceptions were then related to different attributes of a vaccination scheme to have a better understanding of how a higher uptake can be obtained. In the third stage, the effect of the interplay between farmers’ collective behaviour and disease epidemiology on disease rate and vaccination uptake was studied.
Expected utility theory was used in combination with decision analysis and Monte Carlo simulation in chapter 2. The economic risk and monetary outcomes of the vaccination decision were considered, intrinsic or social motives ignored. The theoretical expectation from the analysis is that with high probabilities of herd exposure and disease effects at the start of the outbreak the farmer decides to vaccinate. Re-vaccination is uncertain during the course of the epidemic due to a lower probability of herd exposure and enduring protection against infection from previous vaccination. Factors that make re-vaccination more likely to happen are risk-averse behaviour and farm management aimed at the export of heifers. The decision moment – before or during an epidemic – and the characteristics of the disease – endemic, epidemic or emerging – are important factors in perceptions of disease risk.
Chapters 3 to 5 used data from a survey that was based on the reasoned action approach. Data were analysed with a variety of statistical, mostly multivariate, techniques. The relative importance of the social-psychological constructs in predicting the intention to participate in a hypothetical reactive vaccination scheme against bluetongue was assessed in chapter 3. It was found that intended vaccination behaviour was mainly explained by farmers’ attitude, but also by social pressures from injunctive and descriptive norms. Perceived behavioural control was the least important predictor of intention.
The most influential beliefs underlying the social-psychological constructs were assessed in chapter 4. Results suggested that instrumental beliefs (e.g. risk reduction) as well as experiential beliefs (e.g. animal welfare) were important drivers of the attitude towards vaccination against bluetongue. This indicates that in addition to monetary outcomes of the decision, at least a group of farmers also consider the non-monetary (or non-pecuniary) outcomes. The results further showed that the most influencing referents for the farmer are the veterinarian, his or her family members and colleague dairy farmers (peers). Two influencing control beliefs were associated with the provision of information and perceived trust and confidence in the vaccine safety, effectiveness and government approach to control the disease.
The aim of chapter 5 was to explore factors that could explain heterogeneity in farmers’ attitudinal beliefs. In particular, perceived risk, measured by a relative risk attitude and risk perception, and the Big Five personality traits were associated with variability in these beliefs. Conscientiousness discriminated farmers into a group of ‘vaccination intenders’ and non-intenders although it remained somewhat unclear how it relates to the decision problem, as it can be a sense of duty, achievement striving or both. The perceived risk measures were related to the milk production intensity and also discriminated intenders from non-intenders. These differences in perceived risk indicated that farmers might not be commonly risk averse, however, it is important to account for the domain specificity of risk taking behaviour.
A survey-based discrete choice experiment was used in chapter 6 to study more deeply farmers’ choices for different voluntary bluetongue vaccination scheme designs. A generalised random utility model of farmers’ behaviour allowed for heterogeneity in motives to invest in bluetongue disease control. Results showed that farmers have private economic motives (incentives) to participate in a vaccination scheme, such as to insure the production risk from disease infection and to maintain the export of heifers.
Interaction effects found between social-psychological constructs and specific designs of policy instruments highlighted the importance of perceived trust and confidence in the vaccine safety and effectiveness and in the disease control strategy chosen by animal health authorities. Attitude interacted positively with government communication (information) provided via veterinarians. Descriptive norm interacted positively with a lower perceived probability of adverse effects. This suggests that farmers are more likely to vaccinate if they perceive that others in their social network perform vaccination without experiencing adverse effects. Injunctive norm interacted negatively with a higher level of government subsidy. This suggested a crowding-out mechanism through which subsidization adversely affect farmer’s motivation to comply with the vaccination policy.
The interplay between farmers’ collective behaviour and bluetongue disease epidemiology was studied in chapter 7 with an agent-based model. The utility model specification from chapter 6 was used to describe the decision-making process of farmers. Other components that added to the dynamic nature of the model were a social network structure of the diffusion process of sharing information about vaccination status and a susceptible-latent-infectious-recovered model of disease spread. The effectiveness of different bluetongue vaccinations scheme designs was studied as measured by disease rate and vaccination uptake.
Results of chapter 7 showed that vaccination schemes that focus more on motivating farmers via informational instruments were somewhat more effective than predicted from the comparative static analysis in chapter 6. Motivation via financial incentives resulted in a somewhat lower effectiveness than was predicted from that same model. This might be explained as an emergent effect that evolves under specific vaccination scheme designs from the interactions between farmers themselves and with the environment from which they observe the progress of the disease. These schemes focus more on serving the information needs of farmers and raising the perceived trust and confidence in the disease control approach rather than on incentivising with higher levels of subsidy.
Three themes for livestock disease control emerged from the synthesis of the results in chapter 8, which were subsequently discussed in relation to the wider economic and (social) psychological literature. These themes coincide with shortcoming of the standard economic model of rational choice to describe and predict behaviour. The first theme was about understanding how farmers cope with risk in the context of livestock diseases. The second theme focused on the usefulness of financial compensation as a policy instrument. The third theme discussed the role of trust and social norms. After discussing the implications for policy making, main scientific contributions and suggestions for future research, the chapter concluded that:Dutch dairy farmers who operate large-scale and intensive farms or keep heifers for export are likely to have private economic motives to vaccinate against bluetongue (Chapter 2, 4, 5 and 6).Farmers’ willingness to vaccinate against bluetongue is mostly driven by attitude, followed by perceived social pressures from injunctive norms and descriptive norms. This implies farmers can be motivated intrinsically, extrinsically, or both (Chapter 3).Dutch dairy farmers have intrinsic motives to vaccinate against bluetongue. They do not want to be confronted with animal suffering but want to keep job satisfaction high from working with healthy animals (Chapter 4).Dutch dairy farmers have social motives to vaccinate against bluetongue. They consider what important referents, such as the veterinarian or family members, think they should do and take into account the perceived behaviour of peers (Chapter 3 and 4).
Perceived risk, personality traits and past behaviour are important behavioural variables for explaining the heterogeneity in beliefs to vaccinate against bluetongue (Chapter 5).
The efficacy of financial, incentive based instruments to motivate to vaccinate against bluetongue is heterogeneous and not necessarily positive for each farmer. They are not effective if farmers already expect a positive net benefit from vaccination or if they crowd-out the motivation to comply with the vaccination policy (Chapter 2, 4, 6, 7).
The efficacy of informational policy instruments to motivate farmers to vaccinate against bluetongue is positively affected by farmers’ attitude towards vaccination and in case farmers perceive the communication channels used as credible and trustworthy (Chapter 3, 4, 6).
The efficacy of social interaction mechanisms in policy making, such as the perceived social pressuretovaccinateagainstbluetongue,ispositivelyaffectedbyfarmers’trustandconfidence in the government approach to control the disease (Chapter 4, 6, 7).
On the role of vaccine dose and antigenic distance in the transmission dynamics of Highly Pathogenic Avian Influenza (HPAI) H5N1 virus and its selected mutants in vaccinated animals
Sitaras, Ioannis - \ 2017
Wageningen University. Promotor(en): M.C.M. Jong, co-promotor(en): B. Peeters. - Wageningen : Wageningen University - ISBN 9789463438063 - 209
avian influenza viruses - avian influenza - disease transmission - vaccines - vaccination - dosage - antigenic variation - mutants - mutations - immunity - vaccine development - virology - epidemiology - aviaire influenzavirussen - aviaire influenza - ziekteoverdracht - vaccins - vaccinatie - dosering - antigene variatie - mutanten - mutaties - immuniteit - vaccinontwikkeling - virologie - epidemiologie
Influenza virus infections can cause high morbidity and mortality rates among animals and humans, and result in staggering direct and indirect financial losses amounting to billions of US dollars. Ever since it emerged in 1996 in Guangdong province, People’s Republic of China, one particular highly pathogenic avian influenza (HPAI) H5N1 virus has spread globally, and is responsible for massive losses of poultry, as well as human infections. For these reasons, HPAI H5N1 is considered as one of the viruses possible to cause a future influenza pandemic.
One of the main reasons why influenza is a recurring problem is its ability to constantly evolve through the selection of mutants that are able to avoid immunity (be it natural or acquired). Due to the accumulation of mutations during genome replication, diverse/variant influenza genome sequences co-exist in a virus pool (quasispecies). These sequences can contain mutations that are able to confer selective advantages to the influenza virus given the opportunity. As a consequence, whenever a situation arises that places the virus under any type of pressure that the dominant virus sequence cannot cope with (i.e. immune pressure, selective receptor binding, etc.), the virus with the genome sequence that allows it to better adapt to that particular pressure becomes selected and takes over.
Because of the influenza virus’s high rate of mutations, a global surveillance network is in place to monitor changes in circulating strains among humans that would warrant an update of the vaccines used. For human influenza strains, vaccines are updated frequently (every one or two years) and a similar situation holds true for racehorse vaccination. For avian influenza vaccination, however, the situation is different. In most countries, vaccination against avian influenza is not used, and in the countries where vaccines are used (either as routine or emergency measures), they are not updated as frequently as human vaccines are. In addition, in many instances vaccination against avian influenza viruses has met with some spectacular failures, since it failed to produce a level of immunity that would protect against circulating field strains. These vaccination failures have often been attributed to the fact that without constant vaccine updating (as is done for human influenza), the vaccines used are not able to keep up with continuously evolving antigenic variants selected in the field, and thus to protect poultry against them. In addition, since it is known that immune pressure resulting from vaccination can be a driving force in the evolution of influenza viruses and the selection of immune-escape mutants, there is a school of thought that posits that vaccination against avian influenza is not only a very expensive affair (especially if vaccines need to be frequently updated), but can also lead to selection of mutants that are able to avoid vaccination-induced immunity.
The research reported in this thesis started with addressing the gaps in the knowledge regarding the role of vaccination-induced immunity in the selection of immune-escape mutants of HPAI H5N1, and if there is a way for vaccines to still be able to protect against antigenically-distant variants of the vaccine seed strain, without the need for frequent vaccine updates.
Our first step in studying influenza virus evolution and selection of immune-escape mutants was to investigate how antigenic pressure may drive the selection of such mutants, and what the effect of the selected mutations on the pathogenicity and transmissibility of the mutants may be. Although there exist a variety of methods to select for influenza virus mutations (i.e. monoclonal antibodies, site-directed mutagenesis, reverse genetics, etc.), none of them is representative of selection as it happens in a vaccinated animal. In Chapter 2, we discuss in detail a laboratory-based system we have developed, in which immune-escape mutants are selected using homologous polyclonal chicken sera, similar to how they are selected in the field due to vaccination- induced immune pressure. We find that selection takes place early on, and additional mutations are selected when immune pressure is increased. Antigenic distances between the selected mutants and their parent strains are also increased throughout the selection process, but not in a linear fashion. Our selection system proved to be robust and replicable, and to be representative of selection in the field, since the mutations we selected for are also found in naturally-selected field isolates, and the antigenic distances between our selected mutants and their parent strains are similar to antigenic distances between vaccine strains and field isolates.
We continued our research by addressing the roles played by vaccine dose (and resulting immunity) and antigenic distance between vaccine and challenge strains, in the transmission of HPAI H5N1 viruses, by employing transmission experiments using vaccinated chickens (Chapter 3). To our surprise, we found that the effect of antigenic distances between vaccine and challenge strains on transmission is very small compared to the effect of vaccine dose. We then quantified, for the first time, the minimum level of immunity and minimum percentage of the vaccinated population exhibiting said immunity, in order for vaccines to be able to protect against transmission even of strains that are antigenically distant to the vaccine seed strain. Transmission of such strains in well-vaccinated populations would allow for a scenario where vaccination- induced immunity may drive the selection of immune-escape mutants. Our results show that in order for vaccines to prevent transmission of antigenically distant strains (such as the ones resulting from selection due to immune pressure), the threshold level of immunity against these strains should be ≥23 haemagglutination inhibition units (HIU), in at least 86.5% of the vaccinated population. This level of immunity can be estimated by knowing the antigenic distance between the vaccine and challenge (field) strain, and the HI titre against the vaccine strain, which would then allow the approximate level of immunity against the field strain to be deduced. For example, assuming the HI titre against a vaccine strain is 210 HIU, and the distance with the challenge (field) strain is 24 HIU, according to our results the vaccine should be able to protect against the challenge strain, because the difference in HI titres should be around 26 HIU (i.e. above 23 HIU). These results, taken together with our previous work on selection of mutants, where we showed that the antigenic distances between our mutants and their parent strains are representative of distances found in the field, point to the fact that it is unlikely that vaccination-induced immunity can lead to selection of mutants able to escape it, given that a threshold level of immunity in a minimum percentage of the vaccinated population is achieved. As a consequence, we believe that constant vaccine updating may not be necessary for avian influenza viruses, as long as a threshold level of immunity is maintained. This makes vaccination a more attractive control measure, both from a health perspective and a financial one, than just applying biosecurity measures.
To examine the effect the mutations in the haemagglutinin protein of our selected mutants may have in their transmission among chickens vaccinated with the parent strain, we used reverse genetics techniques to insert the HA gene of our most antigenically distant mutant into the parent strain backbone (Chapter 4). We vaccinated animals with a sub-optimal dose of vaccine, and we concluded that the mutations we selected for did not allow the mutant to avoid even low levels of immunity, such as the ones resulting from a sub-optimal vaccine dose (which resembles a poor field vaccination scenario). At the same time, the HA mutations we selected for did not appear to have a negative effect either on the pathogenicity of the mutant, or its ability to transmit to unvaccinated animals, since both parameters were comparable to the parent strain.
Finally, we studied the role inter-animal variation in immunity – as measured by HI titres – has in the accuracy of antigenic cartography calculations (Chapter 5). We found that using sera from more than one animal significantly increased the accuracy of antigenic distance calculations, since it takes into account individual differences in immune responses to vaccination, an inevitable phenomenon documented in both humans and animals. In addition, we increased the accuracy of antigenic maps by avoiding the use of dimension-reducing algorithms as is currently done. By not reducing the dimensionality of virus positioning in space, our maps retain the original geometry between strains or sera, leading to more accurate positioning (Chapters 2 and 5). We hope that improving the accuracy of antigenic cartography can lead to a more precise surveillance of influenza evolution and better informed decisions regarding the need to update vaccines.
Taken collectively, our results can improve field vaccination outcomes, since they provide guidelines on how to increase vaccination efficiency in stopping transmission of even antigenically-distant strains. In addition, our method for selecting for immune- escape mutants can be a valuable addition to research on influenza virus evolution. Moreover, policy making decisions regarding vaccination against any type of influenza can also benefit from our improvement on antigenic cartography accuracy, saving unnecessary costs in vaccine updating, and reducing morbidity and mortality of both animals and humans.
Socio-economic modelling of rabies control in Flores Island, Indonesia
Wera, Ewaldus - \ 2017
Wageningen University. Promotor(en): Henk Hogeveen, co-promotor(en): Monique Mourits. - Wageningen : Wageningen University - ISBN 9789463430586 - 182
rabies - rabies virus - control programmes - control methods - dogs - indonesia - decision making - vaccination - hondsdolheid - hondsdolheidvirus - bestrijdingsprogramma's - bestrijdingsmethoden - honden - indonesië - besluitvorming - vaccinatie
Rabies is a zoonotic viral disease that can cause encephalomyelitis both in animals and humans. Since its introduction in Flores Island, Indonesia in 1997, it has been a serious public health threat with significant economic consequences. To control the disease, annual dog vaccination campaigns have been implemented to vaccinate all dogs free of any charge. Nevertheless, the campaigns have not been successful in eliminating rabies from the island.
The main objective of this dissertation was to support future decisions on the control of rabies in Flores Island by providing insight into the role of socio-demographic and psychological factors of dog owners in the uptake of rabies control measures and by analyzing the cost-effectiveness of alternative mass dog vaccination strategies.
By means of a cost accounting model, the costs of the currently applied rabies control measures in Flores Island were estimated at US$1.12 million (range: US$0.60–1.47 million) per year. The costs of culling roaming dogs resulted in the highest cost portion (39%), followed by the costs of post-exposure treatment (35%) and mass vaccination (24%).
Risk factors associated with the uptake level of rabies control measures were analysed based upon an extensive survey among 450 dog-owners in the regencies of Sikka and Manggarai. Only 52% of these dog owners had at least one of their dogs vaccinated during the 2012 vaccination campaign. Vaccination uptake was significantly higher for dog owners who resided in Sikka, kept female dogs for breeding, had a monthly income of more than one million rupiah, and had easy access to their village.
A study based on the Theory of Planned Behaviour demonstrated that the actual intention of dog owners to participate in a free-of-charge vaccination campaign was high (> 90%). The attitude item ‘vaccinating dogs reduces rabies cases in humans’, and the perceived behavioural control items ‘availability of time’ and ‘ability to confine dogs’ were shown to be significantly associated with this intention level. Relevant considerations to improve the participation level in future vaccination campaigns are therefore appropriate time management as well as the provision of skills to confine dogs during the vaccination.
The cost-effectiveness of different mass dog vaccination strategies was evaluated by means of a deterministic model simulating transmission of rabies virus through the dog population of one village. Annual vaccination using a short-acting vaccine at a coverage of 50% was far from being cost-effective, suggesting that the currently applied rabies control in Flores Island is not an efficient investment in reducing human rabies burden. An increased investment in either an increase in the current coverage or in a switch from the short-acting vaccine to the long-acting vaccine type would certainly pay off.
Good memories for details improve fish health
Wiegertjes, G.F. - \ 2014
Wageningen : Wageningen University, Wageningen UR - ISBN 9789461739759 - 20
vissen - diergezondheid - immunologie - aquacultuur - celbiologie - vaccinatie - fishes - animal health - immunology - aquaculture - cellular biology - vaccination
C-strain vaccination against Classical Swine Fever: effects on epidemic and final screening
Backer, J.A. ; Loeffen, W.L.A. ; Roermund, H.J.W. van - \ 2013
Lelystad : Central Veterinary Institute
varkenshouderij - klassieke varkenspest - vaccinatie - verspreide infecties - ziekteoverdracht - pig farming - classical swine fever - vaccination - disseminated infections - disease transmission
In this project it is evaluated how the use of C-strain vaccine instead of E2-subunit vaccine will affect the effectiveness of controlling Classical Swine Fever (CSF). To this end a CSF transmission model was developed that describes virus transmission on three different levels: between animals, between pens and between herds. The results of transmission and vaccination experiments as well as the data from the 1997/1998 CSF epidemic in The Netherlands serve to parameterize the model. With the model hypothetical epidemics are simulated under different scenarios.
Economic aspects of C-strain vaccination to control Classical Swine Fever epidemics
Bergevoet, R.H.M. ; Asseldonk, M.A.P.M. van - \ 2013
The Hague : LEI, part of Wageningen UR (LEI memorandum : Agriculture & entrepreneurship ) - 22
klassieke varkenspest - vaccinatie - vaccins - varkenshouderij - classical swine fever - vaccination - vaccines - pig farming
This research is focused on economic differences of emergency vaccination in case of an outbreak of Classical Swine Fever (CSF) in a densely populated livestock area in the Netherlands. It compares the ef-fect of a vaccination to live strategy in which a C-strain vaccine is used with the effects of a E2 subunit vaccine.
Gedifferentieerd bestrijdingsbeleid bij een uitbraak van MKZ : aandacht voor niet-commercieel gehouden dieren
Hagenaars, T.H.J. ; Hengel, R. van den; Asseldonk, Marcel van; Nodelijk, G. ; Bergevoet, R.H.M. - \ 2013
Lelystad : Central Veterinary Institute (CVI rapport / Central Veterinary Institute, 13/CVI0183 ) - 17
mond- en klauwzeer - mond- en klauwzeervirus - virusziekten - risico - diergezondheid - vaccinatie - verplichte vaccinatie - landbouwbeleid - dierenwelzijn - dierlijke productie - varkens - rundvee - schapen - foot and mouth disease - foot-and-mouth disease virus - viral diseases - risk - animal health - vaccination - mandatory vaccination - agricultural policy - animal welfare - animal production - pigs - cattle - sheep
Wat is het extra verspreidingsrisico van geïnfecteerde bedrijven naar niet-geïnfecteerde bedrijven als niet-commercieel gehouden dieren worden gevrijwaard van preventieve ruiming in de eerste week van bestrijding van Mond en Klauwzeer virus (MKZ) in Nederland?
Maatregelen t.b.v. een betere groei van opfokhennen
Wagenaar, J.P. ; Verwer, C. - \ 2012
Wageningen : Wageningen UR - 31 p.
hennen - kippen - pluimveehouderij - biologische landbouw - stress - vaccinatie - dierenwelzijn - pluimvee - dierlijke productie - hens - fowls - poultry farming - organic farming - stress - vaccination - animal welfare - poultry - animal production
In dit project is gekeken welke maatregelen genomen kunnen worden om de groei van biologische opfokhennen te verbeteren, gegeven een huidig toegepast vaccinatieschema. Het gaat hierbij om maatregelen die al toegepast worden en om nieuwe maatregelen die in potentie een positief effect op de groei en ontwikkeling van opfokhennen hebben. Naast een literatuurstudie is ook samen met de praktijk gekeken naar geschikte maatregelen.
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.
|Q-koorts in Nederland: stand van zaken, resultaten van veterinair onderzoek en verwachtingen voor de komende jaren.
Roest, H.I.J. ; Hogerwerf, L. ; Brom, R. Van den; Oomen, T. ; Steenbergen, J.E. Van; Nielen, M. - \ 2011
Tijdschrift voor Diergeneeskunde 136 (2011)5. - ISSN 0040-7453 - p. 340 - 343.
q-koorts - coxiella burnetii - herkauwers - zoönosen - ziekteoverdracht - diergeneeskunde - geitenhouderij - schapenhouderij - vaccinatie - q fever - coxiella burnetii - ruminants - zoonoses - disease transmission - veterinary science - goat keeping - sheep farming - vaccination
Overzicht van de stand van zaken humaan en veterinair anno 2011, enkele resultaten van onderzoek worden samengevat en er wordt een vooruitblik gegeven voor de komende jaren.
Interactions of lactobacilli with the host immune system
Meijerink, M. - \ 2011
Wageningen University. Promotor(en): Jerry Wells; Huub Savelkoul, co-promotor(en): J. Bilsen. - [S.l.] : S.n. - ISBN 9789461730442 - 223
probiotica - immunomodulerende eigenschappen - lactobacillus plantarum - spijsverteringskanaal - voedselallergieën - vaccinatie - probiotics - immunomodulatory properties - lactobacillus plantarum - digestive tract - food allergies - vaccination
The aim of this thesis was to better understand the molecular mechanism of host res-ponses to probiotics. Probiotics can be used to stimulate or regulate immune responses in epithelial and immune cells of the intestinal mucosa and generate beneficial effects on the immune system. Carefully selected probiotics are able to steer the activity of the immune response in a predetermined manner by increasing or decreasing the activity of different aspects of the immune system (e.g. development and activity of T helper subsets). Beneficial effects of strains of probiotics have been established in the treatment and prevention of various intestinal disorders, including allergic diseases and diarrhea. However the precise molecular mechanisms and the strain dependent factors involved are poorly understood. Here in vitro molecular studies and in vivo mechanistic studies were combined in different mouse models to generate new insights into the beneficial mechanisms of selected lactobacilli and identify novel bacterial genes influencing the immune response. A further aim was to investigate the predictive value of in vitro immune assays for the effects of probiotics in vivo.
Chapter 1and chapter 2 describe the current knowledge and understanding of the immunomodulatory effects of different probiotic species and strains on mucosal immune system, dendritic cells (DCs) and the adaptive immune system. The relevance and the implications of in vitro studies for clinical trials or mechanistic research in animal mo-dels are discussed.
Chapter 3and chapter 4 present new insights gained from research on the strain-dependent factors involved in probiotic immune modulation. Extensive variation was observed in the immune responses to 42 L. plantarum strains. These results were used to identify genetic loci that correlated with levels of induced cytokines (such as IL-10 or IL-12) following co-culture with DCs (chapter 3) or peripheral blood mononuclear cells (PBMCs) (chapter 4). This in silico “gene-trait matching” approach led to the identification of several candidate genes in the L. plantarum genome that might modulate the immune cytokine response to L. plantarum. Selective gene deletions mutants were constructed for the candidate genes in L. plantarum WCFS1 and compared to the wild-type strain in immune assays with PBMCs and DCs. The predicted phenotype of the genetic knock-out was confirmed for most of the candidate loci including genes encoding an N-acetyl-glucosamine/galactosamine phosphotransferase system, the LamBDCA quorum sensing system, a predicted transcriptional regulator gene (lp_2991) and components of the plantaricin (bacteriocin) biosynthesis and transport pathway. Transcriptome analysis and qPCR data showed that transcript level of gtcA3, which is predicted to be involved in the glycosylation of cell wall teichoic acids, was substantially increased in the lp_2991 deletion mutant (44- and 29-fold respectively).
In vitroassays for pre-screening of candidate probiotics would benefit from standar-dized methods and cryopreservation techniques for immature DCs (iDCs) or precursor monocytes. Literature on the effects of cryopreservation and thawing of monocytes or monocyte-derived iDCs suggested that this strategy might be useful although bacteria had not been previously used as a stimulus. Thus in chapter 5 we investigated the effects of cryopreservation and thawing of precursor monocytes and iDCs on the maturation and immune response of DCs to potential probiotic strains and bacterial TLR agonists. Surface markers CD83 and CD86 were expressed at similar levels on iDCs generated from cryopreserved or freshly isolated monocytes. Cryopreservation of iDCs led to slightly decreased expression of CD86 and CD83 compared to freshly generated iDCs prepared from unfrozen cells but this did not affect the capacity of DCs to acquire fully mature characteristics after stimulation. In contrast the cytokine response to lipoteichoic acid and bacterial stimulation was altered by cryopreservation of monocytes or iDCs, particularly for IL-12 which was decreased up to 250 fold or even not detected at all. Cryopreservation also decreased TNF-α and IL-1β production in stimulated iDCs but to a lesser extent than for IL-12, depending on the maturation factors used. The amounts of IL-10 produced by stimulated iDCs were increased up to 3.6 fold when iDCs were cryopreserved, but decreased up to 90 fold when generated from cryopreserved monocytes. Immature DCs are often used to investigate the immunomodulatory properties of probiotics and here we showed for the first time that cryopreserved monocytes and cryopreserved iDCs have a skewed cytokine response to microbial stimulation. Therefore we consider that standardization of probiotic screening assays by the use of cryopreservation methods is currently not applicable. The detailed method for generating human monocyte derived DC described in chapter 5 may however be useful for developing standardized immune assays.
In chapter 6 we screened the immunomodulatory properties of 28 commercially available bacterial strains in vitro using human PBMCs and investigated selected strains for their in vivo immunomodulatory potential in an established mouse peanut allergy model. The 28 probiotic strains induced highly variable cytokine profiles in PBMCs. L. salivarius HMI001 (HMI001), L. casei Shirota (LCS) and L. plantarum WCFS1 (WCFS1) were selected for further investigation due to their distinct patterns of IL-10, IL-12 and IFN-γ induction. Prophylactic treatment with both HMI001 and LCS attenuated the Th2 phenotype in the mouse model (reduced mast cell responses and ex vivo IL-4 and/or IL-5 production). In contrast, WCFS1 augmented the Th2 phenotype (increased mast cell and antibody responses and ex vivo IL-4 production). In vitro PBMC screening was useful in selecting strains with anti-inflammatory and Th1 skewing properties. In the case of HMI001 (inducing a high IL-10/IL-12 ratio) and LCS (inducing high amounts of IFN-γ and IL-12) partial protection was seen in a mouse peanut allergy model. However, certain strains may worsen the allergic reaction as shown in the case of WCFS1. This approach indicated that pre-selection of candidate probiotics using in vitro immune assays is useful for selecting strains for translational research in humans.
Probiotics have been shown to increase the efficacy of different vaccines and can be easily consumed in food, and therefore probiotics might be useful in the improvement of current mucosal vaccines. In chapter 7 we have investigated the mechanisms behind the effect of lactobacilli on humoral responses to an intranasal vaccine. In addition to L. rhamnosus GG we selected 6 strains of Lactobacillus plantarum which have strikingly different immunomodulatory properties in vitro and TLR-2/6 activating properties. This selection was based on the approach outlined in chapter 3 and chapter 4 examining the in vitro immune responses of human monocyte derived DCs and PBMCs to 42 different L. plantarum strains. First we established an influenza vaccination model in Balb/c mice that would be sensitive to immunomodulation by lactobacilli, which allowed potential up- and down-regulation by the lactobacilli of the immune response. Strain WCFS1, that induced the lowest IL-10 to IL-12 cytokine ratio in DC co-culture significantly increased vaccine-specific antibody responses to the intranasal vaccine compared to the vaccine control group. Several Lactobacillus strains appeared to increase delayed-type hypersensitivity responses after vaccination compared to the vaccine control group indicating increased Th1-mediated vaccine responses. For strain LMG18021 this was also reflected in the significantly higher vaccine-specific IgG2a to IgG1 antibody ratio. LMG18021, CIP104448 and CIP104450 which have the highest IL-10 to IL-12 ratios of the strains tested, significantly enhanced the ex vivo vaccine-specific induction of IL-10, IL-17A, IL-6 and IL-4 in MLN cells. B1839 which was included as negative control, as it was a low cytokine inducer, did not enhance the vaccine-specific antibody or immune response indicating that the immune-stimulatory properties are important in mediating effects on the vaccine response. Further research is needed to demonstrate that these effects on the vaccine response impact on protection from influenza challenge and to validate the immunomodulatory mechanisms involved. Nevertheless, the in vivo studies described in this thesis support other publications proposing that in vitro immune assays can be useful for predicting which candidate probiotic strains will be most effective in vivo.
Chapter 8 completes this thesis with an overview of the most important findings of this thesis and discusses possible research limitations and future research perspectives. We stress the importance of proper strain selection using in vitro assays, and the use of strategies to identify novel immunomodulatory factors. The results described in this thesis support the rationale of using in vitro co-culture assays for selection of candidate probiotics for in vivo animal experiments or human trials.
Control of Highly Pathogenic Avian Influenza; Epidemiological and economic aspects
Backer, J.A. ; Bergevoet, R.H.M. ; Fischer, E.A.J. ; Nodelijk, G. ; Bosman, K.J. ; Saatkamp, H.W. ; Roermund, H.J.W. van - \ 2011
Den Haag : LEI, part of Wageningen UR (LEI report 2011-032) - ISBN 9789086155200 - 80
aviaire influenzavirussen - pluimveeziekten - dierziekten - pluimvee - ziektebestrijding - vaccinatie - methodologie - efficiëntie - invloeden - epidemiologie - economische aspecten - economische situatie - economie - sociale economie - economische analyse - europese unie - nederland - avian influenza viruses - poultry diseases - animal diseases - poultry - disease control - vaccination - methodology - efficiency - influences - epidemiology - economic aspects - economic situation - economics - socioeconomics - economic analysis - european union - netherlands
Epidemieën van hoog pathogene aviaire influenza (HPAI) kunnen een grote invloed hebben op het dierenwelzijn, de pluimveesector en, vanwege de zoönotische aard, ook op de volksgezondheid. Vanwege de vele mogelijke insleeproutes, reservoirs en mutaties in laag pathogene AI (LPAI) loopt het pluimvee in Nederland voortdurend het gevaar te worden besmet met HPAI. In geval van een uitbraak moeten de besmette boerderijen worden geruimd, moet het transport worden gereguleerd, moeten er beschermings- en toezichtsgebieden worden opgezet en moeten gevaarlijke contacten worden opgespoord, dit alles volgens de vereisten van de EU. Er kunnen ook bestrijdingsmaatregelen worden genomen om de blootgestelde bedrijfsdichtheid in het getroffen gebied te verkleinen door preventief ruimen of vaccineren. Net zoals in 2003, kan een nieuwe HPAI epidemie grote gevolgen hebben voor de pluimveesector. Het bestrijden van aangifteplichtige ziektes zoals AI door grootschalig preventief ruimen, wordt maatschappelijk steeds minder geaccepteerd, en de roep om alternatieve bestrijdingsmaatregelen zoals vaccinatie wordt steeds luider. Dit onderzoek ondersteunt het besluitvormingsproces.
Transmission dynamics of Eimeria acervulina in broilers
Velkers, F.C. - \ 2011
Wageningen University. Promotor(en): Mart de Jong; J.A. Stegeman, co-promotor(en): A. Bouma. - [S.l.] : S.n. - ISBN 9789085859215 - 153
vleeskuikens - eimeria acervulina - coccidiose - ziekteoverdracht - experimentele infectie - oöcysten - polymerase-kettingreactie - ziektebestrijding - vaccins - vaccinatie - epidemiologie - broilers - eimeria acervulina - coccidiosis - disease transmission - experimental infection - oocysts - polymerase chain reaction - disease control - vaccines - vaccination - epidemiology
Control of the intestinal disease coccidiosis, caused by infections with Eimeria species, is a major challenge, especially for the broiler industry. Effective control strategies require a comprehensive understanding of processes that lead to infection and disease in a population. One of the key factors that determine infection dynamics in a flock is the rate of transmission between hosts. Therefore, transmission experiments were carried out to increase the understanding of the underlying mechanisms of Eimeria acervulina infections in broilers, to facilitate improvement of control strategies. An important outcome of the experiments was that the excreted oocyst dose, which may be related to severity of clinical signs, increased during successive generations of infection in the flock, but that the transmission rate was independent of the oocyst dose. This suggests that transmission is not determined by the number of oocysts excreted with faeces of infected birds but, most likely, by the probability of birds to come into contact with infectious faeces. Factors influencing the degree and dispersal of infectious faecal material in the environment, such as movements and (litter pecking) behaviour of chickens, environmental conditions and faeces characteristics, may have a large impact on infection dynamics and efficacy of control measures. Furthermore, it was demonstrated that a previous infection with a wild-type E. acervulina strain significantly reduced oocyst output and transmission after re-infection. After infection with a live vaccine strain, oocyst output following an infection with a wild-type strain was also significantly reduced. However, a significant reduction of transmission of the wild-type strain was not found in groups of broilers that had been infected with the vaccine strain. Nevertheless, it was demonstrated that the live vaccine was efficiently transmitted to initially unvaccinated birds. Furthermore, the level of reduction of oocyst output was equally high for directly vaccinated and the “contact-vaccinated” chickens, that became infected due to ingestion of oocysts excreted by vaccinated birds. These results indicate that transmission of the vaccine can induce protection against high oocyst output for the entire flock, even when not all birds receive the vaccine during the initial mass application. The results of these experiments indicate that influencing the rate of transmission of wild-type and vaccine strains can be important for reducing the adverse effects of flock infections with Eimeria. Furthermore, this thesis has increased insight into some of the underlying factors that determine transmission dynamics of E. acervulina in a broiler flock. Further investigation of these factors may reveal novel targets or facilitate improvement of current strategies for coccidiosis control.
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.
Sustained effects of early-life oral colistin treatment on immune reactivity to intratracheally administered LPS and HuSA in chicken
Lammers, A. ; Zutphen, L.J.W. van; Vries Reilingh, G. de; Parmentier, H.K. - \ 2010
In: Proceeding of the 11th Avian Immunology Research Group Conference, Budapest, Hungary, 7-10 October 2010. - Budapest, Hungary : Diamond Congress LTd. - ISBN 9789638801920 - p. 51 - 51.
vogels - immunologie - immuniteit - b lymfocyten - interferon - receptoren - aviaire influenzavirussen - cytokinen - vaccinatie - immunogenetica - birds - immunology - immunity - b lymphocytes - interferon - receptors - avian influenza viruses - cytokines - vaccination - immunogenetics
Vaccinatie van lelies tegen LMoV: een haalbare of ongewenste resistentiestrategie?
Kock, M.J.D. de - \ 2009
Lisse : PPO Bloembollen en Bomen - 27
leliemozaïekvirus - lilium - lelies - plantenziekten - bloembollen - snijbloemen - plantenziektebestrijding - vaccinatie - immunisatie - nederland - lily mottle virus - lilium - lilies - plant diseases - ornamental bulbs - cut flowers - plant disease control - vaccination - immunization - netherlands
Virusinfecties veroorzaken opbrengstverliezen en beperken tevens het internationale handelsverkeer tussen landen die strikte regelgeving hebben met betrekking tot de aanwezigheid van virussen in het plantenmateriaal. Wanneer een plant met een mild virusisolaat wordt geïnfecteerd, komt het vaak voor dat deze plant niet meer vatbaar (of minder vatbaar) is voor virusisolaten die heftige virussymptomen veroorzaken. Deze natuurlijke manier van geïnduceerde resistentie tegen agressieve virussen wordt cross: protectie genoemd. Het actief besmetten van een plant met een virusisolaat dat milde symptomen laat zien, wordt ook wel ‘vaccineren’ genoemd. Het vaccineren van planten wordt door het Japanse bedrijf Nippon Del Monte (NDM) in de praktijk reeds toegepast. NDM is in het bezit van een mild isolaat van Lilly mottle virus (leliemozaïekvirus, LMoV) dat geen of nauwelijks virussymptomen veroorzaakt en is op zoek naar partners in Nederland om voor dit isolaat de mogelijkheden van cross:protectie te bestuderen. Omdat de vaccinatietechnologie positieve verwachtingen heeft, maar ook onzekerheden, beperkingen en potentiële risico’s kent, wordt in dit rapport toegewerkt naar een collectief besluit of de vaccinatietechnologie in Nederland voeten aan de grond kan gaan krijgen. PPO:BBF heeft een stakeholder: en ketenanalyse gemaakt waarin aangegeven is welke nationale en internationale partijen in de keten betrokken zijn bij de implementatie van de vaccinatie technologie. Tevens is samen met Nederlandse lelieveredelingsbedrijven een lijst met criteria opgesteld waaraan een plantenvaccin (in algemene zin) moet voldoen. In een workshop is de vaccinatietechnologie van NDM getoetst aan deze criteria en vraagstellingen zijn geformuleerd die door middel van vervolgonderzoek beantwoord moeten worden of onderdeel kunnen zijn van validatieonderzoek van de vaccinatietechnologie tegen LMoV onder Nederlandse teeltomstandigheden. Er wordt vooral veel waarde gehecht aan de criteria dat de vaccinatietechnologie niet mag leiden tot teeltbeperkingen, niet mag leiden tot risico:inperkende maatregelen en niet mag leiden tot handelsbeperkingen. Juist omdat introductie van de door NDM voorgestelde vaccinatietechnologie volledig van toepassing is op deze criteria, en deze bezwaren niet eenvoudig op te lossen zijn, is gezamenlijk besloten dat er vanuit Nederland geen interesse is in de ontwikkeling van de vaccinatietechnologie tegen LMoV in lelie. Daarmee komt ook een potentiële collectieve samenwerking met NDM voor een gezamenlijke ontwikkeling van de technologie te vervallen. Tevens wordt er geen vervolgonderzoek opgestart waarin aanvullende onderzoeksvragen worden uitgewerkt. Deze conclusie is samengevat in een Memo die aan NDM is toegestuurd.
Planten inenten hulpmiddel bij gebrek aan resistentie : Cross protection bruikbaar alternatief als resistentie ontbreekt
Kierkels, T. ; Vlak, J.M. ; Heuvelink, E. - \ 2009
Onder Glas 6 (2009)12. - p. 9 - 11.
vaccinatie - ziekteresistentie - courgettegeelmozaïekvirus - Pepinomozaïekvirus - tomaten - gewasbescherming - gastheer parasiet relaties - glastuinbouw - groenten - vaccination - disease resistance - Zucchini yellow mosaic virus - pepino mosaic virus - tomatoes - plant protection - host parasite relationships - greenhouse horticulture - vegetables
Enten met een zwakke virusstam om de plant te beschermen tegen een agressieve variant is met veel ‘mitsen’ en ‘maren’ omgeven. In principe is cross protection, zoals dit heet, mogelijk. De plant vertoont zelf een afweerreactie en de eiwitten van de zwakke stam belemmeren vermenigvuldiging van de agressieve stam. Toch is resistentieveredeling beter. Maar als dat niet mogelijk is, vormt cross protection een alternatief, mits aan zes voorwaarden is voldaan. Internationaal is veel ervaring opgedaan met Zucchini yellow mosaic virus, waartegen een preparaat bestaat. Wellicht is zoiets ook mogelijk bij het pepinomozaïekvirus
Beweegredenen van commerciële veehouders en hobbydierhouders om te vaccineren tegen Blauwtong tijdens een vrijwillige vaccinatiecampagne in 2008 en 2009 in Nederland
Elbers, A.R.W. ; Koeijer, A.A. de; Rijn, P.A. van - \ 2009
Lelystad : Wageningen UR, Centraal Veterinair Instituut (Rapport 09/CVI0311) - 27
diergezondheid - bluetonguevirus - vaccinatie - diergeneeskunde - infectieziekten - animal health - bluetongue virus - vaccination - veterinary science - infectious diseases
Onderzoek naar beweegredenen van veehouders om hun vee in te laten enten tegen het blauwtongvirus
Vaccination against Foot-and-Mouth Disease : differentiating strategies and their epidemiological and economic consequences
Backer, J.A. ; Bergevoet, R.H.M. ; Hagenaars, T.H.J. ; Bondt, N. ; Nodelijk, G. ; Wagenberg, C.P.A. van; Roermund, H.J.W. van - \ 2009
Wageningen : Wageningen UR (LEI report 2009-042) - ISBN 9789086153497 - 158
mond- en klauwzeer - diergeneeskunde - veterinaire producten - vaccinatie - rundveeteelt - geneesmiddeleffecten - economische impact - foot and mouth disease - veterinary science - veterinary products - vaccination - cattle farming - drug effects - economic impact
The effectiveness of different control strategies against Foot-and-Mouth Disease (FMD) were investigated using epidemiological and economic models. A quick and large-scale vaccination within a radius of at least 2km is as effective as preemptive 1-km ring culling to mitigate FMD epidemics. Control measures should primarily target cattle farms. After the epidemic, most seropositive animals are expected on sheep farms and vaccinated cattle farms. An effective end-screening strategy should focus on these farms. Market acceptance by trade partners of products of vaccinated animals can limit the economic consequences of outbreaks of FMD.De effectiviteit van bestrijdingstrategieën tegen Mond-en-Klauwzeer (MKZ) is onderzochtmet behulp van epidemiologische en economische modellen. Het blijkt dat snelle en op grote schaal toegepaste vaccinatie in een straal van 2 km rond geïnfecteerde bedrijven net zo effectief is als ruimen in een straal van 1 km rond geïnfecteerde bedrijven bij het bestrijden van MKZ-uitbraken. Controlemaatregelen moeten vooral worden gericht op rundveebedrijven. Na de epidemie zijn de meeste seropositieve dieren te verwachten. De eindscreening zal zich op schapenbedrijven en gevaccineerde rundveebedrijven moeten richten. Acceptatie door internationale handelspartners van producten van gevaccineerde dieren kan de economische gevolgen van een uitbraak van MKZ beperken.