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Santman-Berends IMGA, Mars MH, Van Duijn L, Van den Broek KWH, Van Schaik G. A quantitative risk-analysis for introduction of Bovine Viral Diarrhoea Virus in the Netherlands through cattle imports. Prev Vet Med 2017; 146:103-113. [PMID: 28992914 DOI: 10.1016/j.prevetmed.2017.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 08/02/2017] [Accepted: 08/02/2017] [Indexed: 10/19/2022]
Abstract
Many countries have implemented control programmes aiming to eradicate Bovine Viral Diarrhoea Virus (BVDV). After obtaining the free status, a risk of re-introduction of the virus through import may remain. Therefore the risk of introduction of BVDV through cattle imports in the Netherlands was quantified and the effectiveness of subsequent intervention measures was assessed. Data, literature and expert opinion were used to estimate values for input parameters to feed a stochastic simulation model. The probability that BVDV was imported was differentiated into persistently infected (PI) cattle, trojan cows that transmitted the virus vertically resulting in a PI foetus (TR) and transient infected cattle (TI). The import risk was stratified to beef, dairy, small scale, suckler, trade, veal and young stock herds. The intervention scenarios that were evaluated consisted of virus testing, a combination of virus testing and antibody testing in pregnant cows, abolishment of imports from high risk countries (i.e. countries with a BVDV prevalence >15%) and a combination of import restrictions and testing prior to import. Each year, 334 (5th and 95th percentile: 65-902) Dutch cattle herds were estimated to be infected with BVDV through import. Veal herds account for most infections associated with import (87%), whereas in the other herd types, only 9 beef, 6 dairy, 2 small scale, 16 suckler, 10 trade and 2 young stock herds are infected through imports per year. Import of PI cattle is the most important risk for introduction in veal herds, while import of TR cows is the main source of BVDV introduction in dairy, small scale and suckler herds. With the intervention scenarios, the number of BVDV infected herds in the Netherlands could be reduced to 81 and 58 herds per year when respectively virus testing or a combination of virus and antibody testing was applied or to 108 herds when import from high risk countries was abolished. With the scenario in which both import from high risk countries was abolished combined with virus and antibody testing, the number of BVDV infected herds could be reduced to 17 herds per year. The risk assessment showed that BVDV is regularly imported in the Netherlands. The import risk can effectively be reduced by implementing diagnostic testing prior to import and only import cattle with a favourable result, eventually combined with certain trade restrictions.
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Affiliation(s)
| | - M H Mars
- GD Animal Health, PO box 9, 7400 AA, Deventer, The Netherlands
| | - L Van Duijn
- GD Animal Health, PO box 9, 7400 AA, Deventer, The Netherlands
| | | | - G Van Schaik
- GD Animal Health, PO box 9, 7400 AA, Deventer, The Netherlands; Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, PO Box 80151, 3508, TD Utrecht, The Netherlands
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Machado G, Mendoza MR, Corbellini LG. What variables are important in predicting bovine viral diarrhea virus? A random forest approach. Vet Res 2015. [PMID: 26208851 PMCID: PMC4513962 DOI: 10.1186/s13567-015-0219-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Bovine viral diarrhea virus (BVDV) causes one of the most economically important diseases in cattle, and the virus is found worldwide. A better understanding of the disease associated factors is a crucial step towards the definition of strategies for control and eradication. In this study we trained a random forest (RF) prediction model and performed variable importance analysis to identify factors associated with BVDV occurrence. In addition, we assessed the influence of features selection on RF performance and evaluated its predictive power relative to other popular classifiers and to logistic regression. We found that RF classification model resulted in an average error rate of 32.03% for the negative class (negative for BVDV) and 36.78% for the positive class (positive for BVDV).The RF model presented area under the ROC curve equal to 0.702. Variable importance analysis revealed that important predictors of BVDV occurrence were: a) who inseminates the animals, b) number of neighboring farms that have cattle and c) rectal palpation performed routinely. Our results suggest that the use of machine learning algorithms, especially RF, is a promising methodology for the analysis of cross-sectional studies, presenting a satisfactory predictive power and the ability to identify predictors that represent potential risk factors for BVDV investigation. We examined classical predictors and found some new and hard to control practices that may lead to the spread of this disease within and among farms, mainly regarding poor or neglected reproduction management, which should be considered for disease control and eradication.
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Affiliation(s)
- Gustavo Machado
- Laboratory of Veterinary Epidemiology, Faculty of Veterinary, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9090, CEP 91540-000, Porto Alegre, RS, Brazil.
| | - Mariana Recamonde Mendoza
- Experimental and Molecular Cardiovascular Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre (HCPA), Av. Ramiro Barcelos, 2350, CEP 99010-115, Porto Alegre, RS, Brazil.
| | - Luis Gustavo Corbellini
- Laboratory of Veterinary Epidemiology, Faculty of Veterinary, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9090, CEP 91540-000, Porto Alegre, RS, Brazil.
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Machado G, Egocheaga RMF, Hein HE, Miranda ICS, Neto WS, Almeida LL, Canal CW, Stein MC, Corbellini LG. Bovine Viral Diarrhoea Virus (BVDV) in Dairy Cattle: A Matched Case-Control Study. Transbound Emerg Dis 2014; 63:e1-13. [DOI: 10.1111/tbed.12219] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Indexed: 11/30/2022]
Affiliation(s)
- G. Machado
- Laboratório de Epidemiologia Veterinária (EPILAB); Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - R. M. F. Egocheaga
- Laboratório de Virologia; Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - H. E. Hein
- Laboratório de Epidemiologia Veterinária (EPILAB); Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - I. C. S. Miranda
- Laboratório de Epidemiologia Veterinária (EPILAB); Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - W. S. Neto
- Laboratório de Epidemiologia Veterinária (EPILAB); Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - L. L. Almeida
- Laboratório de Virologia; Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - C. W. Canal
- Laboratório de Virologia; Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - M. C. Stein
- Departamento de Estatística; Instituto de Matemática; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - L. G. Corbellini
- Laboratório de Epidemiologia Veterinária (EPILAB); Faculdade de Veterinária; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
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Herlekar DA, Shashikant CS, Gurjar AA, Jayarao BM. Presence of viral and bacterial organisms in milk and their association with somatic cell counts. J Dairy Sci 2013; 96:6336-46. [PMID: 23972495 DOI: 10.3168/jds.2013-6631] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 07/04/2013] [Indexed: 11/19/2022]
Abstract
About 20 to 35% of milk samples from cows with intramammary infection or high somatic cell count (SCC) are negative on bacteriological culture analysis. However, little is known about SCC in milk of cows infected with viruses. In the first part of our study, we developed a real-time PCR assay for detection of bovine herpesvirus (BHV) 1, BHV2, and BHV4, and bovine viral diarrhea virus (BVDV) in composite quarter milk samples. A total of 1,479 lactating cows of 1,964 cows in the dairy herd were initially selected because these cows had complete SCC data for at least 3 consecutive test results, of which 139 lactating cows from different lactation age groups were selected randomly and studied extensively. Composite quarter milk samples were collected on 3 alternate days and examined for viruses, SCC, and bacteriological analysis. In total, 10, 28, and 0.7% of the composite quarter milk samples from cows were positive for BHV1, BHV2, and BHV4, respectively; BVDV was not detected in composite quarter milk samples. Bovine herpesvirus was not associated with a particular bacterial species. Our study results indicate that cows positive for BHV in composite quarter milk samples alone are less likely to have elevated SCC compared with cows with bacterial intramammary infection; BHV1, BHV2, and BHV4 are probably not major udder pathogens.
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Affiliation(s)
- D A Herlekar
- Department of Animal Science, The Pennsylvania State University, University Park 16802
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Cowley DJB, Clegg TA, Doherty ML, More SJ. Bovine viral diarrhoea virus seroprevalence and vaccination usage in dairy and beef herds in the Republic of Ireland. Ir Vet J 2012; 65:16. [PMID: 22849554 PMCID: PMC3443026 DOI: 10.1186/2046-0481-65-16] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 07/05/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Bovine viral diarrhoea (BVD) is an infectious disease of cattle with a worldwide distribution. Herd-level prevalence varies among European Union (EU) member states, and prevalence information facilitates decision-making and monitoring of progress in control and eradication programmes. The primary objective of the present study was to address significant knowledge gaps regarding herd BVD seroprevalence (based on pooled sera) and control on Irish farms, including vaccine usage. METHODS Preliminary validation of an indirect BVD antibody ELISA test (Svanova, Biotech AB, Uppsala, Sweden) using pooled sera was a novel and important aspect of the present study. Serum pools were constructed from serum samples of known seropositivity and pools were analysed using the same test in laboratory replicates. The output from this indirect ELISA was expressed as a percentage positivity (PP) value. Results were used to guide selection of a proposed cut-off (PCO) PP. This indirect ELISA was applied to randomly constructed within-herd serum pools, in a cross-sectional study of a stratified random sample of 1,171 Irish dairy and beef cow herds in 2009, for which vaccination status was determined by telephone survey. The herd-level prevalence of BVD in Ireland (percentage positive herds) was estimated in non-vaccinating herds, where herds were classified positive when herd pool result exceeded PCO PP. Vaccinated herds were excluded because of the potential impact of vaccination on herd classification status. Comparison of herd-level classification was conducted in a subset of 111 non-vaccinating dairy herds using the same ELISA on bulk milk tank (BMT) samples. Associations between possible risk factors (herd size (quartiles)) and herd-level prevalence were determined using chi-squared analysis. RESULTS Receiver Operating Characteristics Analysis of replicate results in the preliminary validation study yielded an optimal cut-off PP (Proposed Cut-off percentage positivity - PCO PP) of 7.58%. This PCO PP gave a relative sensitivity (Se) and specificity (Sp) of 98.57% and 100% respectively, relative to the use of the ELISA on individual sera, and was chosen as the optimal cut-off since it resulted in maximization of the prevalence independent Youden's Index.The herd-level BVD prevalence in non-vaccinating herds was 98.7% (95% CI - 98.3-99.5%) in the cross-sectional study with no significant difference between dairy and beef herds (98.3% vs 98.8%, respectively, p = 0.595).An agreement of 95.4% was found on Kappa analysis of herd serological classification when bulk milk and serum pool results were compared in non-vaccinating herds. 19.2 percent of farmers used BVDV vaccine; 81% of vaccinated herds were dairy. A significant association was found between seroprevalence (quartiles) and herd size (quartiles) (p < 0.01), though no association was found between herd size (quartiles) and herd-level classification based on PCO (p = 0.548). CONCLUSIONS The results from this study indicate that the true herd-level seroprevalence to Bovine Virus Diarrhoea (BVD) virus in Ireland is approaching 100%. The results of the present study will assist with national policy development, particularly with respect to the national BVD eradication programme which commenced recently.
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Affiliation(s)
- D J Bosco Cowley
- MSD Animal Health, Red Oak North, South County Business Park, Leopardstown, Dublin 18, Ireland
| | - Tracy A Clegg
- MSD Animal Health, Red Oak North, South County Business Park, Leopardstown, Dublin 18, Ireland
- Centre of Veterinary Epidemiology and Risk Analysis, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Michael L Doherty
- School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Simon J More
- School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Centre of Veterinary Epidemiology and Risk Analysis, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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Eiras C, Arnaiz I, Sanjuán ML, Yus E, Diéguez FJ. Bovine viral diarrhea virus. J Vet Diagn Invest 2012; 24:549-53. [DOI: 10.1177/1040638712440984] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The aim of the present study was to establish a relationship between the results obtained using the enzyme-linked immunosorbent assay (ELISA) technique for antibodies in blood serum and milk at herd level. For this purpose, 325 samples of bulk tank milk were analyzed with 4 antibody ELISAs from dairy herds with a prevalence of seropositive animals; seroprevalence was also evaluated. Data were arranged to analyze the sensitivity of the bulk tank milk test to detect herds with high risk of active infection (>65% seroprevalence) and the specificity to detect those with very few (<5%) or no (0%) seropositive animals, respectively. The sensitivity values ranged from 0.92 to 0.70 and the specificity from 0.83 to 0.54 to detect free herds (0% seroprevalence) and from 0.88 to 0.77 to detect herds with <5% of seropositive animals. In a quantitative approach, Pearson correlation coefficients, reported as a measure of linear association between herd seroprevalence and transformed optical density values recorded in bulk tank milk, ranged from 0.71 to 0.86. According to these results, the 4 antibody ELISAs would be valid tests for carrying out a herd classification program using milk samples.
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Affiliation(s)
- Carmen Eiras
- Laboratory of Animal Health and Production in Galicia, Lugo, Spain (Eiras, Arnaiz)
- Unidade de Epidemioloxía e Sanidade Animal do Instituto de Investigación e Análise Alimentaria, Facultade de Veterinaria de Lugo, Universidade de Santiago de Compostela, Lugo, Spain (Sanjuán, Yus, Diéguez)
| | - Ignacio Arnaiz
- Laboratory of Animal Health and Production in Galicia, Lugo, Spain (Eiras, Arnaiz)
- Unidade de Epidemioloxía e Sanidade Animal do Instituto de Investigación e Análise Alimentaria, Facultade de Veterinaria de Lugo, Universidade de Santiago de Compostela, Lugo, Spain (Sanjuán, Yus, Diéguez)
| | - María L. Sanjuán
- Laboratory of Animal Health and Production in Galicia, Lugo, Spain (Eiras, Arnaiz)
- Unidade de Epidemioloxía e Sanidade Animal do Instituto de Investigación e Análise Alimentaria, Facultade de Veterinaria de Lugo, Universidade de Santiago de Compostela, Lugo, Spain (Sanjuán, Yus, Diéguez)
| | - Eduardo Yus
- Laboratory of Animal Health and Production in Galicia, Lugo, Spain (Eiras, Arnaiz)
- Unidade de Epidemioloxía e Sanidade Animal do Instituto de Investigación e Análise Alimentaria, Facultade de Veterinaria de Lugo, Universidade de Santiago de Compostela, Lugo, Spain (Sanjuán, Yus, Diéguez)
| | - Francisco J. Diéguez
- Laboratory of Animal Health and Production in Galicia, Lugo, Spain (Eiras, Arnaiz)
- Unidade de Epidemioloxía e Sanidade Animal do Instituto de Investigación e Análise Alimentaria, Facultade de Veterinaria de Lugo, Universidade de Santiago de Compostela, Lugo, Spain (Sanjuán, Yus, Diéguez)
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Safarpoor Dehkordi F. Prevalence study of Bovine viral diarrhea virus by evaluation of antigen capture ELISA and RT-PCR assay in Bovine, Ovine, Caprine, Buffalo and Camel aborted fetuses in Iran. AMB Express 2011; 1:32. [PMID: 22018096 PMCID: PMC3223133 DOI: 10.1186/2191-0855-1-32] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 10/21/2011] [Indexed: 11/17/2022] Open
Abstract
Bovine viral diarrhea virus is a pestivirus in the family Flaviviridae that cause abortions and stillbirths in livestock and its traditional diagnosis is based on cell culture and virus neutralization test. In this study, for more sensitive, specific detection and determined the prevalence of virus in aborted Bovine, Ovine, Caprine, Buffalo and Camel fetuses the antigen capture ELISA and RT-PCR were recommended. From the total of 2173 aborted fetuses, 347 (15.96%) and 402 (18.49%) were positive for presence of Bovine viral diarrhea virus by antigen capture ELISA and RT-PCR respectively. Statistical analysis of data showed significant differences between ELISA and RT-PCR for detection of virus in aborted fetuses. These results indicate a high presence of this pathogen in Iran and that RT- PCR is considerably faster and more accurate than ELISA for identification of Bovine viral diarrhea virus. To our knowledge the Camels and Bovine are the most resistant and sensitive to Bovine viral diarrhea's abortions respectively and the prevalence of virus in Caprine is more than Ovine aborted fetuses. This study is the first prevalence report of Bovine viral diarrhea virus in aborted Bovine, Ovine, Caprine, Buffalo and Camel fetuses by evaluation of ELISA and RT-PCR in Iran.
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Laureyns J, Ribbens S, de Kruif A. Control of bovine virus diarrhoea at the herd level: Reducing the risk of false negatives in the detection of persistently infected cattle. Vet J 2010; 184:21-6. [DOI: 10.1016/j.tvjl.2008.11.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 09/10/2008] [Accepted: 11/29/2008] [Indexed: 10/21/2022]
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