The 1997-1998 classical swine fever epidemic in The Netherlands--a survival analysis     

Benard HJ  Stärk KD  Morris RS  Pfeiffer DU  Moser H 《Preventive veterinary medicine》1999,42(3-4):235-248

The aim of this analysis was to characterise the temporal pattern of infection during the 1997/98 classical swine fever (CSF) epidemic in The Netherlands and hence identify and quantify risk factors for infection in different enterprise types and areas. Survival analysis and Cox proportional hazards regression were used to describe the epidemic. Substantial differences in temporal survival patterns (herd breakdown rate) were found between areas where different control policies operated. Factors with a significant influence on the infection hazard of individual herds included: sow numbers as a percentage of total sows and fatteners (HR = 3.38 for mixed herds (0.1–60% sows) vs. fattening herds (0% sows) and HR = 2.74 for breeding herds (60–100% sows) vs. fattening herds), the number of ‘transport contacts per month’ (>0.3 vs. <0.3; HR = 4.11), pig density (pigs/km²) in the area (HR_{1000 pigs} 1.48) and herd size (HR_{100 pigs} = 1.01).

Pre-emptive slaughter in an area appeared to be associated with lower subsequent disease levels. Higher frequency of transport contacts for welfare slaughter during the epidemic, however, well regulated and controlled, was associated with a substantially higher risk of becoming infected. The positive association of a higher pig density with CSF indicates the potential importance of local spread as a factor in disease transmission and emphasizes that dilution of the pig population can contribute to reduction in CSF occurrence. This analysis suggests however, that if pre-emptive slaughter can promptly be applied effectively in an area after initial diagnosis, pig density is then not a significant factor. Mixed and breeding herds had a higher probability of becoming infected than fattening herds, possibly due to different types and frequencies of inter-herd contacts. These contacts continue to some extent during the epidemic, despite the standstill of animal movements.  相似文献   

Spatial and stochastic simulation to evaluate the impact of events and control measures on the 1997-1998 classical swine fever epidemic in The Netherlands. II. Comparison of control strategies     

Nielen M  Jalvingh AW  Meuwissen MP  Horst SH  Dijkhuizen AA 《Preventive veterinary medicine》1999,42(3-4):297-317

Using the spatial, temporal and stochastic simulation model InterCSF, several alternative pre-emptive slaughter strategies that could have been applied in the Dutch Classical Swine Fever (CSF) epidemic of 1997–1998 were evaluated. Furthermore, effects of changes in some disease-spread and disease-control parameters were studied. InterCSF simulates the spread of CSF between farms through local spread and contacts (animals, transport and persons). Disease spread is affected by control measures implemented through different mechanisms (e.g. depopulation of infected farms, pre-emptive slaughter, movement control). The starting point for the evaluation of strategies was a simulated basic scenario, which mimicked the real epidemic. Strategies were compared using epidemiological as well as economic results. Economic results were generated by a separate model (EpiLoss) that calculated the direct losses and consequential losses for farmers and related industries. The comparison of the different alternatives to the basic scenario led to some general conclusions on the Dutch CSF-epidemic. Pre-emptive slaughter seemed to be an effective strategy to reduce the size of an epidemic, if started at an early stage. Economically, pre-emptive slaughter was not as expensive as expected; the resulting smaller size of the epidemic, combined with less welfare slaughter, led to much lower overall losses. Furthermore, although large movement control areas seemed effective in reducing the size of the epidemic, the total losses were relatively high because of subsequent welfare slaughter. If infection probabilities could be reduced, for example by improved biosecurity, the resulting epidemics would be much smaller.  相似文献   

从荷兰花卉业的成功经验论云南花卉产业的发展     

张群 《西部林业科学》2005,34(1):79-84

对荷兰花卉产业的现状及其主要的经验作了介绍, 并就云南省花卉产业发展的利弊作出评述。借鉴荷兰花卉业发展的成功经验, 结合云南的实际, 提出了9条发展云南花卉产业的建议。  相似文献   

The genome of Coxiella burnetii Z3055, a clone linked to the Netherlands Q fever outbreaks,provides evidence for the role of drift in the emergence of epidemic clones     

《Comparative immunology, microbiology and infectious diseases》2014,37(5-6):281-288

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Schmallenberg virus epidemic: Impact on milk production,reproductive performance and mortality in dairy cattle in the Netherlands and Kleve district,Germany     

A.M.B. Veldhuis  I.M.G.A. Santman-Berends  J.M. Gethmann  M.H. Mars  L. van Wuyckhuise  P. Vellema  M. Holsteg  D. Höreth-Böntgen  F.J. Conraths  G. van Schaik 《Preventive veterinary medicine》2014

Schmallenberg virus (SBV), a novel orthobunyavirus that rapidly spread throughout north-western Europe in 2011, caused congenital malformations in lambs and goat kids (Van den Brom et al., 2012) and newborn calves (Hoffmann et al., 2012). The impact of the SBV epidemic seemed limited however, in terms of the number of affected herds with malformed offspring (European Food Safety Authority, 2012b). Nevertheless, little is known with regard to the overall within-herd impact of SBV infection. The objective of the current study was to quantify the impact of the 2011 SBV epidemic on the productivity of dairy cattle in the Netherlands and the district of Kleve, Germany.  相似文献   

Prototyping and farm system modelling—Partners on the road towards more sustainable farm systems?     

B. Sterk  M.K. van Ittersum  C. Leeuwis  F.G. Wijnands 《European Journal of Agronomy》2007,26(4):401-409

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Life cycle of pollen grains in mormoder humus forms of young acid forest soils: a micromorphological approach     

J. M. Van Mourik   《CATENA》2003,54(3):651

Horizons of humus profiles contain pollen and spores. The palynological information of pollen spectra of terrestrial humus forms must be validated by micropedological knowledge of the processes of infiltration, incorporation, conservation, transport and decay of pollen grains in the soil system. This study presents the results of combined palynological and micromorphological analyses of two mormoder humus forms, sampled in the Forestry Gieten, The Netherlands. The aim of this study was to establish the distribution pattern and life cycle of pollen grains in mormoders. The first step of this cycle of pollen grains in the humus profile is eolian deposition on the soil surface. The second step is incorporation of the grains in organic aggregates in the upper part of the F horizon. In ‘acid’ mormoders, grains are embedded by ageing small excrements of micro-arthropods and incorporated in the resulting organic aggregates. In ‘mild’ mormoders, the same process is observable, but additional pollen grains are also directly incorporated (and slightly transported) in medium excrements of small earthworm. The third step in the cycle is release by microbial attack of the aggregates in the lower part of the F horizon and the H and Ah horizons. The fourth step is re-incorporation of the released grains in organic aggregates of ageing small sized excrements of micro-arthropods, which consume decaying root tissue. Not re-incorporated grains will finally mineralise by microbial consumption. Mineralising of released pollen grains is the main process in the mineral AE horizon. Based on knowledge of the distribution pattern and life cycle of pollen grains in mormoders, pollen diagrams can be used for the reconstruction of the forest development.  相似文献   

Learning in context through conflict and alignment: Farmers and scientists in search of sustainable agriculture   总被引：1，自引：0，他引：1  

Jasper?EshuisEmail author  Marian?Stuiver 《Agriculture and Human Values》2005,22(2):137-148

This article analyzes learning in context through the prism of a sustainable dairy-farming project. The research was performed within a nutrient management project that involved the participation of farmers and scientists. Differences between heterogeneous forms of farmers knowledge and scientific knowledge were discursively constructed during conflict and subsequent alignment over the validity and relevance of knowledge. Both conflict and alignment appeared to be essential for learning in context. Conflict spurred learning when disagreeing groups of actors developed their knowledge in order to strengthen their arguments. Conflict caused self-referentiality when the actors no longer listened to each other. This inhibited self-reflection, thus blocking ongoing learning. Nevertheless, after a period of alignment, scientific models and knowledge of farmers were reevaluated and recontextualized. Through determining how to use scientific models and farmers knowledge for further learning, aimed at a shared goal, the participating actors also learned how to learn.Jasper Eshuis is a PhD candidate in the Department of Communication Management at Wageningen University, The Netherlands. His research deals with multiple land use, governance processes, and farmers decision-making. He is currently interested in monitoring and trust.Marian Stuiver is a PhD candidate in the Department of Rural Sociology of Wageningen University, The Netherlands. Her current research focuses on nutrient management, farmers innovation, and co-production of knowledge within the agricultural sciences.  相似文献   

Regional Sediment Deficits in the Dutch Lowlands: Implications for Long-Term Land-Use Options (8 pp)     

Michiel J. van der Meulen  Ad J. F. van der Spek  Ger de Lange  Stephan H. L. L. Gruijters  Serge F. van Gessel  Buu-Long Nguyen  Denise Maljers  Jeroen Schokker  Jan P. M. Mulder  Rob A. A. van der Krogt 《Journal of Soils and Sediments》2007,7(1):9-16

Background, Aim and Scope   Coastal and river plains are the surfaces of depositional systems, to which sediment input is a parameter of key-importance. Their habitation and economic development usually requires protection with dikes, quays, etc., which are effective in retaining floods but have the side effect of retarding sedimentation in their hinterlands. The flood-protected Dutch lowlands (so-called dike-ring areas) have been sediment-starved for up to about a millennium. In addition to this, peat decomposition and soil compaction, brought about by land drainage, have caused significant land subsidence. Sediment deficiency, defined as the combined effect of sediment-starvation and drainage-induced volume losses, has already been substantial in this area, and it is expected to become urgent in view of the forecasted effects of climate change (sea-level rise, intensified precipitation and run-off). We therefore explore this deficiency, compare it with natural (Holocene) and current human sediment inputs, and discuss it in terms of long-term land-use options. Materials and Methods: We use available 3D geological models to define natural sediment inputs to our study area. Recent progress in large-scale modelling of peat oxidation and compaction enables us to address volume loss associated with these processes. Human sediment inputs are based on published minerals statistics. All results are given as first-order approximations. Results: The current sediment deficit in the diked lowlands of the Netherlands is estimated at 136 ± 67 million m3/a. About 85% of this volume is the hypothetical amount of sediment required to keep up with sea-level rise, and 15% is the effect of land drainage (peat decomposition and compaction). The average Holocene sediment input to our study area (based on a total of 145 km3) is ~14 million m3/a, and the maximum (millennium-averaged) input ~26 million m3/a. Historical sediment deficiency has resulted in an unused sediment accommodation space of about 13.3 km3. Net human input of sediment material currently amounts to ~23 million m3/a. Discussion: As sedimentary processes in the Dutch lowlands have been retarded, the depositional system's natural resilience to sea-level rise is low, and all that is left to cope is human countermeasure. Preserving some sort of status quo with water management solutions may reach its limits in the foreseeable future. The most viable long-term solutions therefore seem a combination of allowing for more water in open country (anything from flood-buffer zones to open water) and raising lands that are to be built up (enabling their lasting protection). As to the latter, doubling or tripling the use of filling sand in a planned and sustained effort may resolve up to one half of the Dutch sediment deficiency problems in about a century. Conclusions: Conclusions, Recommendations and Perspectives. We conclude that sediment deficiency – past, present and future – challenges the sustainable habitation of the Dutch lowlands. In order to explore possible solutions, we recommend the development of long-term scenarios for the changing lowland physiography, that include the effects of Global Change, compensation measures, costs and benefits, and the implications for long-term land-use options. Recommendations and Perspectives: -  相似文献   

The immune system of cyprinid fish. Oxytetracycline and the regulation of humoral immunity in carp (Cyprinus carpio)     

G.T. Rijkers  R. Van Oosterom  W.B. Van Muiswinkel 《Veterinary immunology and immunopathology》1981,2(3):281-290

The antibiotic oxytetracycline (oxyTC) was administered either by mixing with food or by intraperitoneal injections. In oxyTC treated animals decreased serum immunoglobulin levels were found. The primary anti-sheep red blood cell (SRBC) response was measured by enumerating plaque forming cells (PFC). It was observed that the PFC response was depressed by 80–95% in oxyTC treated animals. When an anti-SRBC serum was injected together with SRBC the immunosuppressive effect of oxyTC was absent. A secondary anti-SRBC response was not inhibited by oxyTC. On base of the results a model for antigen presentation and the interaction between macrophages, T- and B-like cells during primary and secondary responses in fish is proposed. In primary responses cellular interaction is needed to develop a proper immune response whereas after a high antigen dose challenge SRBC might behave as a T-independent antigen.  相似文献