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1.
J Helminthol ; 94: e125, 2020 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-32036795

RESUMEN

Our objective was to measure the efficacy of ivermectin (IVM) and benzimidazoles (BZ, i.e. fenbendazole and albendazole) in 15 cattle farms in western France and southern Italy. A total of 11 groups were treated with IVM and 11 with BZ. Efficacy was assessed by calculating the percentage of faecal egg count reduction (%FECR) using the pre- and post-treatment arithmetic means. Anthelmintic resistance was considered to be present when the %FECR was <95% and the lower limit of the 95% confidence interval <90%. For IVM, the percentages of FECR ranged from 73% to 100%. Lack of efficacy to IVM was detected in two farms out of four in France, but was not detected in any of the seven farms in Italy. For BZ, the percentages of FECR ranged from 95% to 100%. No case of BZ resistance was detected in the five farms in France and the six farms in Italy.


Asunto(s)
Antihelmínticos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades Gastrointestinales/veterinaria , Nematodos/efectos de los fármacos , Infecciones por Nematodos/veterinaria , Animales , Bencimidazoles/uso terapéutico , Bovinos , Enfermedades de los Bovinos/parasitología , Granjas , Heces/parasitología , Francia , Enfermedades Gastrointestinales/tratamiento farmacológico , Enfermedades Gastrointestinales/parasitología , Tracto Gastrointestinal/parasitología , Italia , Ivermectina/uso terapéutico , Infecciones por Nematodos/tratamiento farmacológico , Recuento de Huevos de Parásitos
2.
Nano Lett ; 16(4): 2363-8, 2016 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-26998817

RESUMEN

Resonant Raman spectroscopy is a powerful tool for providing information about excitons and exciton-phonon coupling in two-dimensional materials. We present here resonant Raman experiments of single-layered WS2 and WSe2 using more than 25 laser lines. The Raman excitation profiles of both materials show unexpected differences. All Raman features of WS2 monolayers are enhanced by the first-optical excitations (with an asymmetric response for the spin-orbit related XA and XB excitons), whereas Raman bands of WSe2 are not enhanced at XA/B energies. Such an intriguing phenomenon is addressed by DFT calculations and by solving the Bethe-Salpeter equation. These two materials are very similar. They prefer the same crystal arrangement, and their electronic structure is akin, with comparable spin-orbit coupling. However, we reveal that WS2 and WSe2 exhibit quite different exciton-phonon interactions. In this sense, we demonstrate that the interaction between XC and XA excitons with phonons explains the different Raman responses of WS2 and WSe2, and the absence of Raman enhancement for the WSe2 modes at XA/B energies. These results reveal unusual exciton-phonon interactions and open new avenues for understanding the two-dimensional materials physics, where weak interactions play a key role coupling different degrees of freedom (spin, optic, and electronic).

3.
Phys Rev Lett ; 117(24): 247702, 2016 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-28009222

RESUMEN

In this Letter, both the manipulation of valley-polarized currents and the optical-like behaviors of Dirac fermions are theoretically explored in polycrystalline graphene. When strain is applied, the misorientation between two graphene domains separated by a grain boundary can result in a mismatch of their electronic structures. Such a discrepancy manifests itself in a strong breaking of the inversion symmetry, leading to perfect valley polarization in a wide range of transmission directions. In addition, these graphene domains act as different media for electron waves, offering the possibility to modulate and obtain negative refraction indexes.

4.
Parasitology ; 141(3): 326-35, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24229764

RESUMEN

Fasciola hepatica is a pathogenic trematode parasite of ruminants with a global distribution. Here, we briefly review the current epidemiology of bovine fasciolosis in Europe and discuss the progress made over the last decade in the diagnosis, impact on production and prediction of F. hepatica in cattle. Advances in diagnosis have led to significantly improved coprological and serological methods to detect presence of infection. Diagnostic test results have been correlated with intensity of infection and associated production losses, unravelling the impact on carcass weight and milk yield in modern cattle production systems. The economic impact of fasciolosis may, however, go beyond the direct impacts on production as evidence shows that F. hepatica can modulate the immune response to some co-infections. Control of bovine fasciolosis remains hampered by the limitations of the currently available flukicidal drugs: few drugs are available to treat dairy cows, many have low efficacies against juvenile stages of F. hepatica and there is evidence for the development of drug resistance. This makes research into the prediction of risk periods, and thus the optimum application of available drugs more pertinent. In this field, the recent research focus has been on understanding spatial risk and delivering region-specific spatial distribution maps. Further advances in epidemiological and economic research on bovine fasciolosis are expected to deliver farm-specific economic assessments of disease impact, to leverage non-chemotherapeutic management options and to enhance a more targeted use of anthelmintics.


Asunto(s)
Antihelmínticos/uso terapéutico , Enfermedades de los Bovinos/diagnóstico , Fasciola hepatica/aislamiento & purificación , Fascioliasis/veterinaria , Animales , Bovinos , Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/epidemiología , Europa (Continente)/epidemiología , Fascioliasis/diagnóstico , Fascioliasis/tratamiento farmacológico , Fascioliasis/epidemiología
5.
Heredity (Edinb) ; 109(4): 246-53, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22828900

RESUMEN

Knowledge of the degree of temporal stability of population genetic structure and composition is important for understanding microevolutionary processes and addressing issues of human impact of natural populations. We know little about how representative single samples in time are to reflect population genetic constitution, and we explore the temporal genetic variability patterns over a 30-year period of annual sampling of a lake-resident brown trout (Salmo trutta) population, covering 37 consecutive cohorts and five generations. Levels of variation remain largely stable over this period, with no indication of substructuring within the lake. We detect genetic drift, however, and the genetically effective population size (N(e)) was assessed from allele-frequency shifts between consecutive cohorts using an unbiased estimator that accounts for the effect of overlapping generation. The overall mean N(e) is estimated as 74. We find indications that N(e) varies over time, but there is no obvious temporal trend. We also estimated N(e) using a one-sample approach based on linkage disequilibrium (LD) that does not account for the effect of overlapping generations. Combining one-sample estimates for all years gives an N(e) estimate of 76. This similarity between estimates may be coincidental or reflecting a general robustness of the LD approach to violations of the discrete generations assumption. In contrast to the observed genetic stability, body size and catch per effort have increased over the study period. Estimates of annual effective number of breeders (N(b)) correlated with catch per effort, suggesting that genetic monitoring can be used for detecting fluctuations in abundance.


Asunto(s)
Variación Genética , Genética de Población/estadística & datos numéricos , Trucha/genética , Animales , Demografía , Femenino , Frecuencia de los Genes , Flujo Genético , Genotipo , Lagos , Desequilibrio de Ligamiento , Masculino , Densidad de Población , Suecia
6.
J Dairy Sci ; 95(6): 2977-87, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22612935

RESUMEN

Current control practices against gastrointestinal nematodes in dairy cows rely strongly on anthelmintic use. To reduce the development of anthelmintic resistance or disposition of drug residues in the environment, novel control approaches are currently proposed that target anthelmintic treatment to individual animals instead of the whole herd. However, such selective treatment strategies come with additional costs for labor and diagnostics and, so far, no studies have addressed whether they could be economically sustainable. The objectives of this study were to (1) investigate the economic effects at farm level of whole-herd versus more selective anthelmintic treatment strategies in adult dairy cows, and (2) determine how these economic effects depend on level of infection and herd size. A Monte Carlo simulation, fed by current epidemiological and economical knowledge, was used to estimate the expected economic effects and possible variation of different control strategies under Belgian conditions. Four treatment strategies were compared with a baseline situation in which no treatments were applied: whole herd at calving (S1), selective at calving with (S2) or without (S3) treatment of the first-calf cows, and whole-herd when animals are moved from grazing to the barn in the fall (housing treatment, S4). The benefit per lactation for an average dairy herd varied between -$2 and $131 (average $64) for S1, between -$2 and $127 (average $62) for S2, between -$17 and $104 (average $43) for S3, and between -$41 and $72 (average $15) for S4. The farmer's risk associated with any treatment strategy, as indicated by the width of the 95% credible intervals of economic benefit of anthelmintic treatment, decreased with increasing level of exposure, as assessed by bulk tank milk ELISA. The order of the different strategies when sorted by expected benefit was robust to changes in economic input parameters. We conclude that, on average, strategies applying anthelmintic treatment at calving outperform a strategy applying treatment at housing. Within the strategies that applied treatment at calving, more selective treatment strategies can be economically sustainable. However, given the large variation in possible benefits within each treatment strategy, decision support systems are needed to account for the multitude of cow, epidemiological, and economic factors that determine the economics of nematode control and select the optimal treatment strategy for a specific farm.


Asunto(s)
Antinematodos/economía , Enfermedades de los Bovinos/prevención & control , Infecciones por Nematodos/veterinaria , Animales , Antinematodos/uso terapéutico , Bovinos , Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/economía , Análisis Costo-Beneficio , Industria Lechera/economía , Industria Lechera/métodos , Femenino , Lactancia , Modelos Económicos , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/economía , Infecciones por Nematodos/prevención & control
7.
Int J Parasitol ; 52(10): 659-665, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35917951

RESUMEN

Control of infections with Dictyocaulus viviparus is difficult due to its volatile epidemiology. In the absence of predictive models, 'vigilance and treatment' is today's mainstay for control. In order to evaluate the potential of predictive model development to support a more preventative approach, this longitudinal study aimed at understanding the influence of weather factors on D. viviparus bulk tank milk antibody ELISA results. Bulk tank milk samples were analysed with a Major Sperm Protein-based ELISA (expressed as an optical density ratio) twice monthly on 717 Flemish dairy farms during the grazing season (April-October) in 2018. Meteorological data of the sampled farms were obtained at 1 km spatial scale using the ALARO-SURFEX climate model. A mixed effects model showed that the bulk tank milk optical density ratio was significantly associated with the month of sampling, evapotranspiration, temperature and its quadratic term, the number of hot days and the number of rainy days in the 7-8 weeks prior to sampling. There were significant farm effects involved. The model's accuracy to predict bulk tank milk optical density ratio infection status was 80%, while optical density ratios were generally overestimated by 38%. Inclusion of the previous (2-week-old) optical density ratio values increased accuracy to 86% and reduced the mean square error. We conclude that meteorological parameters have a predictive value for bulk tank milk optical density ratio results, while further research should evaluate model improvements through the addition of herd management factors as well as confirm the predictive power through external validation in additional farms and years.


Asunto(s)
Enfermedades de los Bovinos , Infecciones por Dictyocaulus , Bovinos , Animales , Masculino , Dictyocaulus , Leche , Infecciones por Dictyocaulus/epidemiología , Estudios Longitudinales , Industria Lechera/métodos , Anticuerpos Antihelmínticos/análisis , Enfermedades de los Bovinos/epidemiología , Semen/química , Ensayo de Inmunoadsorción Enzimática/veterinaria
8.
Adv Parasitol ; 115: 171-227, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35249662

RESUMEN

Anthelmintic resistance (AR) is a growing concern for effective parasite control in farmed ruminants globally. Combatting AR will require intensified and integrated research efforts in the development of innovative diagnostic tests to detect helminth infections and AR, sustainable anthelmintic treatment strategies and the development of complementary control approaches such as vaccination and plant-based control. It will also require a better understanding of socio-economic drivers of anthelmintic treatment decisions, in order to support a behavioural shift and develop targeted communication strategies that promote the uptake of evidence-based sustainable solutions. Here, we review the state-of-the-art in these different fields of research activity related to AR in helminths of livestock ruminants in Europe and beyond. We conclude that in the advent of new challenges and solutions emerging from continuing spread of AR and intensified research efforts, respectively, there is a strong need for transnational multi-actor initiatives. These should involve all key stakeholders to develop indicators of infection and sustainable control, set targets and promote good practices to achieve them.


Asunto(s)
Antihelmínticos , Helmintiasis Animal , Helmintos , Nematodos , Infecciones por Nematodos , Enfermedades de las Ovejas , Animales , Antihelmínticos/farmacología , Antihelmínticos/uso terapéutico , Resistencia a Medicamentos , Helmintiasis Animal/tratamiento farmacológico , Ganado , Infecciones por Nematodos/parasitología , Rumiantes/parasitología , Ovinos , Enfermedades de las Ovejas/tratamiento farmacológico , Enfermedades de las Ovejas/parasitología , Enfermedades de las Ovejas/prevención & control
9.
Adv Parasitol ; 118: 85-176, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36088084

RESUMEN

Diagnosis of gastrointestinal nematodes in livestock and companion animals has been neglected for years and there has been an historical underinvestment in the development and improvement of diagnostic tools, undermining the undoubted utility of surveillance and control programmes. However, a new impetus by the scientific community and the quickening pace of technological innovations, are promoting a renaissance of interest in developing diagnostic capacity for nematode infections in veterinary parasitology. A cross-cutting priority for diagnostic tools is the development of pen-side tests and associated decision support tools that rapidly inform on the levels of infection and morbidity. This includes development of scalable, parasite detection using artificial intelligence for automated counting of parasitic elements and research towards establishing biomarkers using innovative molecular and proteomic methods. The aim of this review is to assess the state-of-the-art in the diagnosis of helminth infections in livestock and companion animals and presents the current advances of diagnostic methods for intestinal parasites harnessing (i) automated methods for copromicroscopy based on artificial intelligence, (ii) immunodiagnosis, and (iii) molecular- and proteome-based approaches. Regardless of the method used, multiple factors need to be considered before diagnostics test results can be interpreted in terms of control decisions. Guidelines on how to apply diagnostics and how to interpret test results in different animal species are increasingly requested and some were recently made available in veterinary parasitology for the different domestic species.


Asunto(s)
Nematodos , Parásitos , Animales , Inteligencia Artificial , Ganado , Mascotas , Proteómica
10.
J Fish Biol ; 79(7): 2074-82, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22141907

RESUMEN

Census (N(C)) and effective population size (N(e)) were estimated for a lake-resident population of brown trout Salmo trutta as 576 and 63, respectively. The point estimate of the ratio of effective to census population size (N(e):N(C)) for this population is 0.11 with a range of 0.06-0.26, suggesting that N(e):N(C) ratio for lake-resident populations agree more with estimates for fishes with anadromous life histories than the small ratios observed in many marine fishes.


Asunto(s)
Lagos , Trucha/fisiología , Animales , Censos , Conservación de los Recursos Naturales , Explotaciones Pesqueras , Frecuencia de los Genes , Desequilibrio de Ligamiento , Densidad de Población , Suecia , Trucha/genética
11.
Vet Parasitol ; 292: 109414, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33752038

RESUMEN

Dictyocaulus viviparus, the causative agent of bovine parasitic bronchitis, is an important parasite of dairy cattle. Infections can lead to substantial economic losses, due to mortality, reduced weight gain and milk production and treatment costs. There have been relatively few studies investigating herd management risk factors for infections with D. viviparus and lungworm-associated production losses. The aims of this study were (1) to assess the impact of (sub)clinical lungworm infections on productivity in dairy cows and, (2) to identify or confirm risk factors, related to herd management, for infections in grazing dairy cattle. Using a recombinant Major Sperm Protein (MSP)-based ELISA, the presence of D. viviparus antibodies in bulk tank milk (BTM) samples was evaluated on 717 and 634 farms at two-week intervals during two grazing seasons (2018 and 2019). Associations between milk antibody levels and production data (mean milk yield in kg/cow/day, percentage of fat and protein) were assessed, as well as associations with putative risk factors in the herd management, gathered through a questionnaire survey. In both years, there was a substantial, but non-significant, difference in the annual mean milk yield on farms with at least one BTM sample above the cut-off of 0.41 ODR, compared with the mean milk yield on farms that stayed under this threshold on each sampling day (-0.17 and -0.70 kg milk/cow/day in 2018 and 2019, respectively). In 2019, this association was stronger, and significant, when the cut-off was exceeded in at least two consecutive BTM samples (-1.74 kg milk/cow/day). BTM results were also significantly negatively associated with the closest milk production data during the two-weekly BTM sampling intervals in 2019. A single or two consecutive positive tests were used in the risk factor analysis as a proxy for lungworm-associated milk yield losses. Purchase of new animals (Odds Ratio (OR) = 2.68) and the proportion of the first grazing season covered by preventive anthelmintic treatment (OR up to 3.88, depending on proportion) were positively associated with lungworm-associated milk yield losses, while mowing at least 50 % of the pastures (OR = 0.57) was negatively associated with lungworm-associated milk yield losses. Our results suggest that the ELISA holds promise to identify herds with significant production losses due to lungworm infections, under the condition that BTM sampling is done repeatedly during the grazing season. Based on the confirmed risk factors, adjustments of the farm management could perhaps mitigate these losses.


Asunto(s)
Enfermedades de los Bovinos/parasitología , Infecciones por Dictyocaulus/parasitología , Lactancia/fisiología , Enfermedades Pulmonares Parasitarias/veterinaria , Leche/fisiología , Crianza de Animales Domésticos , Animales , Bovinos , Enfermedades de los Bovinos/patología , Infecciones por Dictyocaulus/patología , Femenino , Enfermedades Pulmonares Parasitarias/parasitología , Enfermedades Pulmonares Parasitarias/patología , Factores de Riesgo
12.
Nanoscale Adv ; 2(1): 256-263, 2020 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-36133971

RESUMEN

Aharonov-Bohm (AB) interferences in the quantum Hall regime can be achieved, provided that electrons are able to transmit between two edge channels in nanostructures. Pioneering approaches include quantum point contacts in 2DEG systems, bipolar graphene p-n junctions, and magnetic field heterostructures. In this work, defect scattering is proposed as an alternative mechanism to achieve AB interferences in polycrystalline graphene. Indeed, due to such scattering, the extended defects across the sample can act as tunneling paths connecting quantum Hall edge channels. Consequently, strong AB oscillations in the conductance are predicted in polycrystalline graphene systems with two parallel grain boundaries. In addition, this general approach is demonstrated to be applicable to nano-systems containing two graphene barriers with functional impurities and perspectively, can also be extended to similar systems of 2D materials beyond graphene.

13.
Vet Parasitol ; 288: 109280, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33160192

RESUMEN

The lungworm Dictyocaulus viviparus can have a major impact on bovine health and productivity. Enzyme-Linked Immunosorbent Assays (ELISA), based on a recombinant Major Sperm Protein (MSP), have been developed to detect D. viviparus-specific antibodies in bulk tank milk (BTM). The objectives of this study are to assess the association between BTM optical density ratio's (ODR) and farmer-reported lungworm outbreaks based on the clinical sign "coughing" throughout the grazing season and to compare the sensitivity and specificity of two ELISAs under field conditions. The Hannover MSP-ELISA and the prototype Svanova MSP-ELISA were used for the detection of D. viviparus antibodies in BTM samples on 717 dairy farms during the 2018 grazing season. Assuming all herds to be truly lungworm infected, the results show that the Svanova ELISA had a lower sensitivity (40-65%) and specificity (75-90%) for the detection of D. viviparus infections in BTM compared to the Hannover ELISA, which had a sensitivity of 42% and 74% and specificity of 100% and 98% at a cut-off of 0.41 ODR and 0.25 ODR, respectively. Therefore, analyses of the associations between milk antibody levels and farmer-reported outbreaks during the 2018 and 2019 grazing season were assessed using the Hannover ELISA, on 717 and 634 farms, respectively. A positive association was found between a farmer-reported outbreak and having at least two consecutive positive BTM ODR's at a cut-off of 0.41 in 2018 (Odds Ratio (OR) = 5.5) and 2019 (OR = 2.8). Furthermore, there was a significant association between a farmer-reported outbreak and having a positive BTM ODR in August (OR 2018 = 4.4; OR 2019 = 2.8) and October (OR 2018 = 3.7; OR 2019 = 1.8). On the farms with a farmer-reported outbreak and positive BTM samples, over half (2018 = 77%; 2019 = 57%) of the positive ODR's were situated before the outbreak and 47% (2018) and 42% (2019) within 12 weeks before the outbreak. In conclusion, there is a positive association between farmer-reported outbreaks and the occurrence of a positive BTM sample at the cut-off of 0.41 ODR using the Hannover ELISA.


Asunto(s)
Anticuerpos Antihelmínticos/análisis , Enfermedades de los Bovinos/epidemiología , Infecciones por Dictyocaulus/epidemiología , Dictyocaulus/aislamiento & purificación , Brotes de Enfermedades/veterinaria , Ensayo de Inmunoadsorción Enzimática/veterinaria , Animales , Bélgica/epidemiología , Bovinos , Enfermedades de los Bovinos/parasitología , Infecciones por Dictyocaulus/parasitología , Ensayo de Inmunoadsorción Enzimática/instrumentación , Femenino , Proteínas del Helminto/análisis , Leche , Prevalencia , Sensibilidad y Especificidad , Estudios Seroepidemiológicos
14.
Int J Parasitol ; 50(2): 133-144, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31981671

RESUMEN

Gastrointestinal nematodes are a significant threat to the economic and environmental sustainability of keeping livestock, as adequate control becomes increasingly difficult due to the development of anthelmintic resistance in some systems and climate-driven changes to infection dynamics. To mitigate any negative impacts of climate on gastrointestinal nematode epidemiology and slow anthelmintic resistance development, there is a need to develop effective, targeted control strategies that minimise the unnecessary use of anthelmintic drugs and incorporate alternative strategies such as vaccination and evasive grazing. However, the impacts climate and gastrointestinal nematode epidemiology may have on the optimal control strategy are generally not considered, due to lack of available evidence to drive recommendations. Parasite transmission models can support control strategy evaluation to target field trials, thus reducing the resources and lead-time required to develop evidence-based control recommendations incorporating climate stochasticity. Gastrointestinal nematode population dynamics arising from natural infections have been difficult to replicate and model applications have often focussed on the free-living stages. A flexible framework is presented for the parasitic phase of gastrointestinal nematodes, GLOWORM-PARA, which complements an existing model of the free-living stages, GLOWORM-FL. Longitudinal parasitological data for two species that are of major economic importance in cattle, Ostertagia ostertagi and Cooperia oncophora, were obtained from seven cattle farms in Belgium for model validation. The framework replicated the observed seasonal dynamics of infection in cattle on these farms and overall, there was no evidence of systematic under- or over-prediction of faecal egg counts. However, the model under-predicted the faecal egg counts observed on one farm with very young calves, highlighting potential areas of uncertainty that may need further investigation if the model is to be applied to young livestock. The model could be used to drive further research into alternative parasite control strategies such as vaccine development and novel treatment approaches, and to understand gastrointestinal nematode epidemiology under changing climate and host management.


Asunto(s)
Tracto Gastrointestinal/parasitología , Ganado/parasitología , Nematodos/aislamiento & purificación , Infecciones por Nematodos , Animales , Antihelmínticos/uso terapéutico , Bélgica/epidemiología , Bovinos , Enfermedades de los Bovinos/parasitología , Clima , Heces/parasitología , Ivermectina/uso terapéutico , Infecciones por Nematodos/epidemiología , Infecciones por Nematodos/veterinaria , Ostertagia/aislamiento & purificación , Ostertagiasis/epidemiología , Ostertagiasis/veterinaria , Recuento de Huevos de Parásitos/veterinaria , Dinámica Poblacional , Estaciones del Año , Strongyloidea/aislamiento & purificación , Trichostrongyloidea/aislamiento & purificación
15.
Prev Vet Med ; 182: 105103, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32750638

RESUMEN

We report a European wide assessment of the economic burden of gastrointestinal nematodes, Fasciola hepatica (common liver fluke) and Dictyocaulus viviparus (bovine lungworm) infections to the ruminant livestock industry. The economic impact of these parasitic helminth infections was estimated by a deterministic spreadsheet model as a function of the proportion of the ruminant population exposed to grazing, the infection frequency and intensity, the effect of the infection on animal productivity and mortality and anthelmintic treatment costs. In addition, we estimated the costs of anthelmintic resistant nematode infections and collected information on public research budgets addressing helminth infections in ruminant livestock. The epidemiologic and economic input data were collected from international databases and via expert opinion of the Working Group members of the European Co-operation in Science and Technology (COST) action COMbatting Anthelmintic Resistance in ruminants (COMBAR). In order to reflect the effects of uncertainty in the input data, low and high cost estimates were obtained by varying uncertain input data arbitrarily in both directions by 20 %. The combined annual cost [low estimate-high estimate] of the three helminth infections in 18 participating countries was estimated at € 1.8 billion [€ 1.0-2.7 billion]. Eighty-one percent of this cost was due to lost production and 19 % was attributed to treatment costs. The cost of gastrointestinal nematode infections with resistance against macrocyclic lactones was estimated to be € 38 million [€ 11-87 million] annually. The annual estimated costs of helminth infections per sector were € 941 million [€ 488 - 1442 million] in dairy cattle, € 423 million [€ 205-663 million] in beef cattle, € 151million [€ 90-213 million] in dairy sheep, € 206 million [€ 132-248 million] in meat sheep and € 86 million [€ 67-107 million] in dairy goats. Important data gaps were present in all phases of the calculations which lead to large uncertainties around the estimates. Accessibility of more granular animal population datasets at EU level, deeper knowledge of the effects of infection on production, levels of infection and livestock grazing exposure across Europe would make the largest contribution to improved burden assessments. The known current public investment in research on helminth control was 0.15 % of the estimated annual costs for the considered parasitic diseases. Our data suggest that the costs of enzootic helminth infections which usually occur at high prevalence annually in ruminants, are similar or higher than reported costs of epizootic diseases. Our data can support decision making in research and policy to mitigate the negative impacts of helminth infections and anthelmintic resistance in Europe, and provide a baseline against which to measure future changes.


Asunto(s)
Enfermedades de los Bovinos/economía , Costo de Enfermedad , Infecciones por Dictyocaulus/economía , Fascioliasis/veterinaria , Enfermedades de las Cabras/economía , Enfermedades de las Ovejas/economía , Animales , Bovinos , Dictyocaulus/fisiología , Europa (Continente) , Fasciola hepatica/fisiología , Fascioliasis/economía , Cabras , Ovinos , Oveja Doméstica
16.
Nanotechnology ; 20(37): 375501, 2009 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-19706940

RESUMEN

Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma; the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano(2)hybrids is quantified for the detection of toxic species like NO(2), CO, C(2)H(5)OH and C(2)H(4).


Asunto(s)
Gases/análisis , Gases/química , Oro/química , Nanopartículas del Metal/química , Nanotecnología/métodos , Nanotubos de Carbono/química , Nanopartículas del Metal/ultraestructura , Microscopía Electrónica de Transmisión , Nanotubos de Carbono/ultraestructura
17.
Vet Parasitol ; 162(3-4): 295-305, 2009 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-19342178

RESUMEN

Twenty-five, castrated male Holstein-cross calves, between 4 and 5 months of age, weighing 156.5+/-12.2 kg and reared under conditions designed to minimise the risk of parasitic infection, were allocated to one of the five treatment groups on the basis of initial bodyweight. The groups were (1) ad libitum (ad lib) fed controls (ALC); (2) ad lib fed infected (INF) and treated with topical eprinomectin on Day 56; (3) controls pair-fed with the INF group (PFC); (4) ad lib fed controls treated with eprinomectin on Days 0 and 56 (E-ALC) and (5) ad lib fed, infected and treated with eprinomectin on Days 0 and 56 (E-INF). Infection comprised a trickle infection with the equivalent of 10,000 larvae of Ostertagia ostertagi per day from Day 0 to Day 56 and the study concluded on Day 77. Parameters measured throughout the study included: liveweight, feed intake, faecal egg counts; plasma pepsinogen, gastrin, ghrelin and leptin; plasma antibodies to adult O. ostertagi. No significant differences in feed intake or liveweight gain were observed between any of the different groups, a finding thought to result from the high quality of feed offered. Significant differences between the INF and control groups however were observed in faecal egg counts, plasma pepsinogen, gastrin and O. ostertagi antibodies, which were all elevated, and leptin, which was reduced. Values of these parameters for the E-INF group were intermediate between the INF and ALC groups. Plasma ghrelin showed no association with either feed intake or parasitism. Further studies are needed to fully elucidate the roles of various biochemical and neuroendocrine mediators for inappetence in ruminants with parasitic gastroenteritis.


Asunto(s)
Anticuerpos Antihelmínticos/sangre , Enfermedades de los Bovinos/sangre , Ostertagia/inmunología , Ostertagiasis/veterinaria , Animales , Antihelmínticos/uso terapéutico , Bovinos , Enfermedades de los Bovinos/inmunología , Enfermedades de los Bovinos/parasitología , Heces/parasitología , Conducta Alimentaria , Gastrinas/sangre , Ghrelina/sangre , Ivermectina/análogos & derivados , Ivermectina/uso terapéutico , Leptina/sangre , Masculino , Ostertagiasis/sangre , Ostertagiasis/tratamiento farmacológico , Ostertagiasis/parasitología , Recuento de Huevos de Parásitos , Pepsinógeno A/sangre , Tiempo
18.
Vet Parasitol ; 157(1-2): 100-7, 2008 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-18692964

RESUMEN

Measurement of antibodies to Ostertagia ostertagi in bulk tank milk (BTM) has value as a diagnostic indicator for potential production losses and anthelmintic treatment responses in dairy herds. Most of the recent data on O. ostertagi antibodies in milk have been generated in Belgium and Canada; the purpose of this study was to determine the range of O. ostertagi antibody levels in several European countries. BTM samples were collected during the autumn of 2005 and 2006 from a total of 1185 dairy herds from dairy farming regions in Denmark, Germany, Ireland, Italy, the Netherlands, Portugal, Spain and the United Kingdom. Antibody titres to O. ostertagi were determined by indirect ELISA and expressed as optical density ratios (ODR). In addition, relationships between ODR and management practices were investigated. For each country the mean ODR and the 25th-75th percentile values were determined. Mean BTM ODR values in herds with access to yards, paddocks and pastures ranged from 0.3 in Italy to 0.6 in Portugal and the UK/Ireland. The BTM ODR values obtained in this study were generally lower than those described in the literature for Belgium, but comparable with those in Canada. Variations between different European countries appeared to reflect different husbandry practices, particularly those related to access to pasture. The association analyses showed correlations between the BTM O. ostertagi ODR, outside access and grazing management, consistent with the publications from Belgium and Canada. When diagnostic values appropriate for different production situations and environments have been further validated, the test will provide an objective, quantitative assessment of the O. ostertagi status of a dairy herd and the possible impact this may have on performance and potential responses to anthelmintic treatment. This represents a significant step forward in evidence-based medicine for dairy veterinarians, advisors and farmers.


Asunto(s)
Anticuerpos Antihelmínticos/análisis , Enfermedades de los Bovinos/parasitología , Leche/química , Ostertagia/inmunología , Ostertagiasis/veterinaria , Animales , Canadá/epidemiología , Bovinos , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/inmunología , Industria Lechera , Ensayo de Inmunoadsorción Enzimática/veterinaria , Europa (Continente)/epidemiología , Femenino , Lactancia/fisiología , Ostertagiasis/epidemiología , Ostertagiasis/parasitología
19.
Transbound Emerg Dis ; 65 Suppl 1: 5-8, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29878664

RESUMEN

DISCONTOOLS (DISease CONtrol TOOLS) is an open-access database to assist public and private funders of animal health research in identifying research gaps and planning future research. This database is supported by a range of national funders of animal health research in Europe, with industry providing secretariat support. Information in the database is generated by disease-specific expert groups. In this DISCONTOOLS Supplement, contributing experts expanded their gap analyses into review papers for 15 diseases, covering zoonotic, production and epizootic diseases. Across this diverse array of diseases, it is clear that fundamental research on host-pathogen relationships and immune responses remains critical for evidence-based development of novel vaccines, pharmaceuticals and diagnostics to improve animal health. Furthermore, it is also obvious that there is need to better utilize economics and knowledge regarding "human factors" to optimise uptake and use of a broad range of tools and insights.


Asunto(s)
Enfermedades de los Animales/prevención & control , Animales Domésticos , Control de Enfermedades Transmisibles/métodos , Enfermedades Transmisibles/veterinaria , Investigación/tendencias , Animales , Bases de Datos Factuales , Brotes de Enfermedades/prevención & control , Transmisión de Enfermedad Infecciosa/prevención & control , Europa (Continente)/epidemiología , Humanos , Medicina Veterinaria
20.
Prev Vet Med ; 153: 15-23, 2018 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-29653730

RESUMEN

Emerging anthelmintic resistance emphasizes the need for sustainable control approaches against gastrointestinal nematode (GIN) infections in cattle. The uptake of diagnostic methods for sustainable control could enable more informed treatments and reduce excessive anthelmintic use. Unfortunately, the adoption of such methods remains relatively poor. A better understanding of farmers' motivations and behaviour would help to develop applicable advises and communication strategies for sustainable worm control strategies. A previous study created a general model for adoption intention of GIN diagnostics on dairy farms and measured the most important factors driving this intention (Vande Velde et al., 2015). The current research aimed to dig deeper into this model for the beliefs underlying these factors, and to identify additional factors impelling this specific behaviour. Data were collected through 22 semi-structured interviews with dairy farmers. Using analytic induction analysis, data were moved between deduction and induction. Results show that the adoption process of diagnostic methods for GIN occurs through three different phases: adoption intention, actual adoption and maintenance. Low infection awareness and low priority ('top of mind') of the disease are important barriers for adopting sustainable GIN control. Secondly, farmer behaviour is guided by two important social norms: the opinion of their veterinarian and their fellow farmers. However, farmers hold an incongruent relationship with both norms throughout different stages of behaviour: they do not value other farmers' opinions as a positive reference (intention phase), but follow and mimic their behaviour as a group (action phase). The veterinarian is seen as the most important positive reference, but also the responsible actor for GIN control. As such, the farmers do not hold themselves responsible for implementing sustainable control strategies. Thirdly, different types of motivations influence different sorts of behaviours. Sustainable behaviour such as use of diagnostics will be influenced by moral motives, while management behaviour such as treatment is raised by more economic motives. Finally, not only performing, but also maintaining behaviour is important to fully address the adoption of sustainable control. As such, to maintain the adoption on farm, planning could be an important contribution. These insights can be used by animal health organizations and industry by exploiting motivations, social norms and planning to encourage the uptake of diagnostic approaches in GIN control.


Asunto(s)
Enfermedades de los Bovinos/prevención & control , Industria Lechera , Parasitosis Intestinales/veterinaria , Infecciones por Nematodos/veterinaria , Animales , Bélgica , Bovinos , Enfermedades de los Bovinos/parasitología , Agricultores , Intención , Parasitosis Intestinales/prevención & control , Nematodos , Infecciones por Nematodos/prevención & control , Encuestas y Cuestionarios
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