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Galler M, Lüdge K, Humphries R, Mulchrone K, Hövel P. Deterministic and stochastic effects in spreading dynamics: A case study of bovine viral diarrhea. CHAOS (WOODBURY, N.Y.) 2021; 31:093129. [PMID: 34598439 DOI: 10.1063/5.0058688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Bovine viral diarrhea (BVD) is a disease in cattle with complex transmission dynamics that causes substantial economic losses and affects animal welfare. The infection can be transient or persistent. The mostly asymptomatic persistently infected hosts are the main source for transmission of the virus. This characteristic makes it difficult to control the spreading of BVD. We develop a deterministic compartmental model for the spreading dynamics of BVD within a herd and derive the basic reproduction number. This epidemiological quantity indicates that identification and removal of persistently infected animals is a successful control strategy if the transmission rate of transiently infected animals is small. Removing persistently infected animals from the herd at birth results in recurrent outbreaks with decreasing peak prevalence. We propose a stochastic version of the compartmental model that includes stochasticity in the transmission parameters. This stochasticity leads to sustained oscillations in cases where the deterministic model predicts oscillations with decreasing amplitude. The results provide useful information for the design of control strategies.
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Affiliation(s)
- Markus Galler
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Kathy Lüdge
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Rory Humphries
- School of Mathematical Sciences, University College Cork, Western Road, Cork T12 XF64, Ireland
| | - Kieran Mulchrone
- School of Mathematical Sciences, University College Cork, Western Road, Cork T12 XF64, Ireland
| | - Philipp Hövel
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
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2
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ISODA N, ASANO A, ICHIJO M, OHNO H, SATO K, OKAMOTO H, NAKAO S, KATO H, SAITO K, ITO N, USUI A, TAKAYAMA H, SAKODA Y. Assessment of the cost effectiveness of compulsory testing of introduced animals and bulk tank milk testing for bovine viral diarrhea in Japan. J Vet Med Sci 2019; 81:577-585. [PMID: 30828031 PMCID: PMC6483914 DOI: 10.1292/jvms.18-0671] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/18/2019] [Indexed: 11/22/2022] Open
Abstract
Bovine viral diarrhea (BVD) is a chronic disease of cattle caused by infection with BVD virus (BVDV) and can result in economic losses within the livestock industry. In Japan, the test and culling policy is a basic control measure, and implementation of an adequate vaccination program is recommended as a national policy. In addition, optional control measures, including compulsory testing of introduced animals and bulk tank milk (BTM) testing as a mass screening method, are used in several provinces, but their efficacy has not been completely assessed. We evaluated these control measures using the scenario tree model of BVD in Japan, developed in the previous study. The model outputs indicated that compulsory testing of all introduced cattle, rather than only heifers and/or non-vaccinated cattle, was cost effective and reduced the risk of BVDV introduction due to animal movement and that BTM testing could effectively monitor most part of the cattle population. Vaccination coverage and BVDV prevalence among introduced cattle could also affect the cost effectiveness of compulsory testing of targeted cattle, particularly under low vaccination coverage or high BVDV prevalence. However, even with the implementation of a highly effective monitoring scheme for many years, BVD risk could not be eliminated; it instead converged at a very low level (0.02%). Disease models with a cost-effective output could be a powerful tool in developing a control scheme for chronic animal diseases, including BVD, with the consent of relevant stakeholders.
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Affiliation(s)
- Norikazu ISODA
- Unit of Risk Analysis and Management, Research Center for
Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-ku, Sapporo, Hokkaido
001-0020, Japan
- Global Station for Zoonosis Control, Global Institute for
Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido
001-0020, Japan
| | - Akihiro ASANO
- Hokkaido Nemuro Livestock Hygiene Service Center, 69,
Betsukai-Midorimachi, Betsukai, Notsuke-gun, Hokkaido 086-0214, Japan
| | - Michiru ICHIJO
- Hokkaido Nemuro Livestock Hygiene Service Center, 69,
Betsukai-Midorimachi, Betsukai, Notsuke-gun, Hokkaido 086-0214, Japan
| | - Hiroshi OHNO
- Hokkaido Veterinary Medical Association Nemuro Branch, 119,
Betsukai-Midorimachi, Betsukai, Notsuke-gun, Hokkaido 086-0292, Japan
| | - Kazuhiko SATO
- Western Nemuro Operation Center, Hokkaido Higashi
Agricultural Mutual Aid Association, 109, Nishi-Syunbetsu, Betsukai, Notsuke-gun, Hokkaido
088-2576, Japan
| | - Hirokazu OKAMOTO
- Northern Nemuro Operation Center, Hokkaido Higashi
Agricultural Mutual Aid Association, 37, Tawara-bashi 14, Naka-shibetsu, Sibetsu-gun,
Hokkaido 086-1137, Japan
| | - Shigeru NAKAO
- Southern Nemuro Operation Center, Hokkaido Higashi
Agricultural Mutual Aid Association, 119, Betsukai-Midorimachi, Betsukai, Notsuke-gun,
Hokkaido 086-0292, Japan
| | - Hajime KATO
- Southern Nemuro Operation Center, Hokkaido Higashi
Agricultural Mutual Aid Association, 119, Betsukai-Midorimachi, Betsukai, Notsuke-gun,
Hokkaido 086-0292, Japan
| | - Kazuma SAITO
- Betsukai Town Office, 280, Betsukai-Tokiwa, Betsukai,
Notsuke-gun, Hokkaido 086-0205, Japan
| | - Naoki ITO
- The Federation of Agricultural Cooperatives in Nemuro, 2,
Higashi 1, Minami 1, Naka-shibetsu, Sibetsu-gun, Hokkaido 086-1006, Japan
| | - Akira USUI
- Hokkaido Veterinary Medical Association Nemuro Branch, 119,
Betsukai-Midorimachi, Betsukai, Notsuke-gun, Hokkaido 086-0292, Japan
| | - Hiroaki TAKAYAMA
- Hokkaido Nemuro Livestock Hygiene Service Center, 69,
Betsukai-Midorimachi, Betsukai, Notsuke-gun, Hokkaido 086-0214, Japan
| | - Yoshihiro SAKODA
- Global Station for Zoonosis Control, Global Institute for
Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido
001-0020, Japan
- Laboratory of Microbiology, Department of Disease Control,
Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo,
Hokkaido 060-0018, Japan
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3
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Iotti B, Valdano E, Savini L, Candeloro L, Giovannini A, Rosati S, Colizza V, Giacobini M. Farm productive contexts and the dynamics of bovine viral diarrhea (BVD) transmission. Prev Vet Med 2019; 165:23-33. [PMID: 30851924 DOI: 10.1016/j.prevetmed.2019.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 08/22/2018] [Accepted: 02/01/2019] [Indexed: 11/19/2022]
Abstract
Bovine viral diarrhea (BVD) is a viral disease that affects cattle and that is endemic to many European countries. It has a markedly negative impact on the economy, through reduced milk production, abortions, and a shorter lifespan of the infected animals. Cows becoming infected during gestation may give birth to Persistently Infected (PI) calves, which remain highly infective throughout their life, due to the lack of immune response to the virus. As a result, they are the key driver of the persistence of the disease both at herd scale, and at the national level. In the latter case, the trade-driven movements of PIs, or gestating cows carrying PIs, are responsible for the spatial dispersion of BVD. Past modeling approaches to BVD transmission have either focused on within-herd or between-herd transmission. A comprehensive portrayal, however, targeting both the generation of PIs within a herd, and their displacement throughout the country due to trade transactions, is still missing. We overcome this by designing a multiscale metapopulation model of the spatial transmission of BVD, accounting for both within-herd infection dynamics, and its spatial dispersion. We focus on Italy, a country where BVD is endemic and seroprevalence is very high. By integrating simple within-herd dynamics of PI generation, and the highly-resolved cattle movement dataset available, our model requires minimal arbitrary assumptions on its parameterization. We use our model to study the role of the different productive contexts of the Italian market, and test possible intervention strategies aimed at prevalence reduction. We find that dairy farms are the main drivers of BVD persistence in Italy, and any control strategy targeting these farms would lead to significantly higher prevalence reduction, with respect to targeting other production compartments. Our multiscale metapopulation model is a simple yet effective tool for studying BVD dispersion and persistence at country level, and is a good instrument for testing targeted strategies aimed at the containment or elimination of this disease. Furthermore, it can readily be applied to any national market for which cattle movement data is available.
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Affiliation(s)
- Bryan Iotti
- University of Turin, Department of Veterinary Sciences, Turin 10095, Italy
| | - Eugenio Valdano
- Universitat Rovira i Virgili, Departament d'Enginyeria Informàtica i Matemàtiques, Tarragona 43007, Spain
| | - Lara Savini
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, Teramo 64100, Italy
| | - Luca Candeloro
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, Teramo 64100, Italy
| | - Armando Giovannini
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, Teramo 64100, Italy
| | - Sergio Rosati
- University of Turin, Department of Veterinary Sciences, Turin 10095, Italy
| | - Vittoria Colizza
- Sorbonne Universités, UPMC Univ Paris 06, Institut Pierre Louis d'Epidémiologie et de Santé Publique, Paris 75011, France.
| | - Mario Giacobini
- University of Turin, Department of Veterinary Sciences, Turin 10095, Italy
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Smith RL, Sanderson MW, Jones R, N'Guessan Y, Renter D, Larson R, White BJ. Economic risk analysis model for bovine viral diarrhea virus biosecurity in cow-calf herds. Prev Vet Med 2013; 113:492-503. [PMID: 24360189 DOI: 10.1016/j.prevetmed.2013.11.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 11/18/2013] [Accepted: 11/21/2013] [Indexed: 11/20/2022]
Abstract
A stochastic model was designed to calculate the cost-effectiveness of biosecurity strategies for bovine viral diarrhea virus (BVDV) in cow-calf herds. Possible sources of BVDV introduction considered were imported animals, including the calves of pregnant imports, and fenceline contact with infected herds, including stocker cattle raised in adjacent pastures. Spread of BVDV through the herd was modeled with a stochastic SIR model. Financial consequences of BVDV, including lost income, treatment costs, and the cost of biosecurity strategies, were calculated for 10 years, based on the risks of a herd with a user-defined import profile. Results indicate that importing pregnant animals and stockers increased the financial risk of BVDV. Strategic testing in combination with vaccination most decreased the risk of high-cost outbreaks in most herds. The choice of a biosecurity strategy was specific to the risks of a particular herd.
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Affiliation(s)
- Rebecca L Smith
- Department of Clinical Sciences, Kansas State University, Manhattan, KS 66502, United States
| | - Michael W Sanderson
- Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66502, United States.
| | - Rodney Jones
- Department of Agricultural Economics, Kansas State University, Manhattan, KS 66502, United States
| | - Yapo N'Guessan
- Department of Agricultural Economics, Kansas State University, Manhattan, KS 66502, United States
| | - David Renter
- Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66502, United States
| | - Robert Larson
- Department of Clinical Sciences, Kansas State University, Manhattan, KS 66502, United States
| | - Brad J White
- Department of Clinical Sciences, Kansas State University, Manhattan, KS 66502, United States
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5
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Tinsley M, Lewis FI, Brülisauer F. Network modeling of BVD transmission. Vet Res 2012; 43:11. [PMID: 22325043 PMCID: PMC3295666 DOI: 10.1186/1297-9716-43-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 02/10/2012] [Indexed: 11/10/2022] Open
Abstract
Endemic diseases of cattle, such as bovine viral diarrhea, have significant impact on production efficiency of food of animal origin with consequences for animal welfare and climate change reduction targets. Many modeling studies focus on the local scale, examining the on-farm dynamics of this infectious disease. However, insight into prevalence and control across a network of farms ultimately requires a network level approach. Here, we implement understanding of infection dynamics, gained through these detailed on-farm modeling studies, to produce a national scale model of bovine viral diarrhea virus transmission. The complex disease epidemiology and on-farm dynamics are approximated using SIS dynamics with each farm treated as a single unit. Using a top down approach, we estimate on-farm parameters associated with contraction and subsequent clearance from infection at herd level. We examine possible control strategies associated with animal movements between farms and find measures targeted at a small number of high-movement farms efficient for rapid and sustained prevalence reduction.
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Affiliation(s)
- Mark Tinsley
- C, Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, USA.
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A stochastic risk-analysis model for the spread of bovine viral diarrhea virus after introduction to naïve cow–calf herds. Prev Vet Med 2010; 95:86-98. [DOI: 10.1016/j.prevetmed.2010.02.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 02/15/2010] [Accepted: 02/18/2010] [Indexed: 11/24/2022]
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7
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Viet AF, Krebs S. Bovine viral diarrhoea virus: economic evaluation of outbreaks by modelling. Vet J 2009; 185:103-4. [PMID: 19846331 DOI: 10.1016/j.tvjl.2009.09.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 09/20/2009] [Indexed: 10/20/2022]
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8
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Smith RL, Sanderson MW, Renter DG, Larson RL, White BJ. A stochastic model to assess the risk of introduction of bovine viral diarrhea virus to beef cow–calf herds. Prev Vet Med 2009; 88:101-8. [DOI: 10.1016/j.prevetmed.2008.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 07/10/2008] [Accepted: 08/08/2008] [Indexed: 10/21/2022]
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Nath M, Woolliams JA, Bishop SC. Assessment of the dynamics of microparasite infections in genetically homogeneous and heterogeneous populations using a stochastic epidemic model1. J Anim Sci 2008; 86:1747-57. [DOI: 10.2527/jas.2007-0615] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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10
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Ogut H, Bishop SC. A stochastic modelling approach to describing the dynamics of an experimental furunculosis epidemic in Chinook salmon, Oncorhynchus tshawytscha (Walbaum). JOURNAL OF FISH DISEASES 2007; 30:93-100. [PMID: 17298564 DOI: 10.1111/j.1365-2761.2007.00791.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A susceptible-infected-removed (SIR) stochastic model was compared to a susceptible-latent-infectious-removed (SLIR) stochastic model in terms of describing and capturing the variation observed in replicated experimental furunculosis epidemics, caused by Aeromonas salmonicida. The epidemics had been created by releasing a single infectious fish into a group of susceptible fish (n = 43) and progress of the epidemic was observed for 10 days. This process was replicated in 70 independent groups. The two stochastic models were run 5000 times and after every run and every 100 runs, daily mean values of each compartment were compared to the observed data. Both models, the SIR model (R(2) = 0.91), and the SLIR model (R(2) = 0.90) were successful in predicting the number of fish in each category at each time point in the experimental data. Moreover, between-replicate variability in the stochastic model output was similar to between-replicate variability in the experimental data. Generally, there was little change in the goodness of fit (R(2)) after 200 runs in the SIR model whereas 500 runs were necessary to have stable predictions with the SLIR model. In the SIR model, on an individual replicate basis, approximately 80% of 5000 simulated replicates had R(2) = 0.7 and above, whereas this ratio was slightly higher (82%) with the SLIR model. In brief, both models were equally effective in predicting the observed data and its variance but the SLIR model was advantageous because it differentiated the latent, i.e. infected but not having the ability to discharge pathogen, from the infectious fish.
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Affiliation(s)
- H Ogut
- Faculty of Marine Sciences, Karadeniz Technical University, Surmene, Trabzon, Turkey.
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Viet AF, Fourichon C, Seegers H. Review and critical discussion of assumptions and modelling options to study the spread of the bovine viral diarrhoea virus (BVDV) within a cattle herd. Epidemiol Infect 2006; 135:706-21. [PMID: 17109768 PMCID: PMC2870629 DOI: 10.1017/s095026880600745x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Relevance of epidemiological models depends on assumptions on the population structure and dynamics, on the biology of the host-parasite interaction, and on mathematical modelling. In this paper we reviewed published models of the bovine viral diarrhoea virus (BVDV) spread within a herd. Modelling options and assumptions on herd dynamics and BVDV transmission were discussed. A cattle herd is a population with a controlled size. Animals are separated into subgroups according to their age or their physiological status inducing heterogeneity of horizontal transmission. Complexity of models results from: (1) horizontal and vertical virus transmission, (2) birth of persistently infected animals, (3) excretion by transiently and persistently infected animals. Areas where there was a lack of knowledge were identified. Assumptions on the force of infection used to model the horizontal virus transmission were presented and discussed. We proposed possible ways of improving models (e.g. force of infection, validation) and essential model features for further BVDV models.
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Affiliation(s)
- A-F Viet
- Unit of Animal Health Management, Veterinary School - INRA, Nantes, France.
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Nath M, Woolliams JA, Bishop SC. Identifying critical parameters in the dynamics and control of microparasite infection using a stochastic epidemiological model. J Anim Sci 2004; 82:384-96. [PMID: 14974535 DOI: 10.2527/2004.822384x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A stochastic epidemic model is presented to study infection transmission dynamics, and hence epidemic severity and disease incidence, in a closed population. The aim was to understand the relative importance of various parameters that influence the dynamics of potential epidemics, particularly when the genetic mechanisms of resistance or tolerance to infection are considered. Simulations explored the effect of varying the transmission coefficient, latent period, recovery period, mortality rate, and the period of loss of immunity on overall epidemic outcomes. The critical parameters influencing the transmission of infection, and hence disease incidence, were the transmission coefficient, the latent period, and the recovery period; the period of loss of immunity had only trivial effects. Ideally, control strategies should decrease the transmission coefficient and/or increase the latent period and/or decrease the recovery period. By equating measured traits with disease transmission parameters, the model described in this paper can be used to identify which disease resistance genes or QTL will be truly effective in helping to develop disease-resistant livestock that suffer fewer epidemics and side-effects of infection. In particular, emphases should be placed on finding genes that decrease the transmission of infection, increase the latent period, or decrease the recovery period.
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Affiliation(s)
- M Nath
- Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, UK.
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Viet AF, Fourichon C, Seegers H, Jacob C, Guihenneuc-Jouyaux C. A model of the spread of the bovine viral-diarrhoea virus within a dairy herd. Prev Vet Med 2004; 63:211-36. [PMID: 15158572 DOI: 10.1016/j.prevetmed.2004.01.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2003] [Revised: 01/05/2004] [Accepted: 01/31/2004] [Indexed: 10/26/2022]
Abstract
Wet BVDSim (a stochastic simulation model) was developed to study the dynamics of the spread of the bovine viral-diarrhoea virus (BVDV) within a dairy herd. This model took into account herd-management factors (common in several countries), which influence BVDV spread. BVDSim was designed as a discrete-entity and discrete-event simulation model. It relied on two processes defined at the individual-animal level, with interactions. The first process was a semi-Markov process and modelled the herd structure and dynamics (demography, herd management). The second process was a Markov process and modelled horizontal and vertical virus transmission. Because the horizontal transmission occurs by contacts (nose-to-nose) and indirectly, transmission varied with the separation of animals into subgroups. Vertical transmission resulted in birth of persistently infected (PI) calves. Other possible consequences of a BVDV infection during the pregnancy period were considered (pregnancy loss, immunity of calves). The outcomes of infection were modelled according to the stage of pregnancy at time of infection. BVDV pregnancy loss was followed either by culling or by a new artificial insemination depending on the modelled farmer's decision. Consistency of the herd dynamics in the absence of any BVDV infection was verified. To explore the model behaviour, the virus spread was simulated over 10 years after the introduction of a near-calving PI heifer into a susceptible 38 cow herd. Different dynamics of the virus spread were simulated, from early clearance to persistence of the virus 10 years after its introduction. Sensitivity of the model to the uncertainty on transmission coefficient was analysed. Qualitative validation consisted in comparing the bulk-milk ELISA results over time in a sample of herds detected with a new infection with the ones derived from simulations.
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Affiliation(s)
- Anne-France Viet
- Unit of Animal Health Management, Veterinary School and INRA, P.O. Box 40706, 44307 Nantes Cedex 03, France.
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Abstract
In this paper, Dr. Martin reviews the progress in analytical approaches used in veterinary medicine between the 1970s and today. The newer applications are used in such activities as monitoring/surveillance, analysis of observational study data, evaluation of tests in the absence of gold standards, the analysis of clustered data (including geographically clustered data) and modeling disease in populations. Future work will be more complex but will demand an increased emphasis on ways to enhance our biological understanding of the results of data analysis and modeling.
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Affiliation(s)
- Wayne Martin
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ont., Canada N1G 2W1.
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Muñoz-Zanzi CA, Johnson WO, Thurmond MC, Hietala SK. Pooled-sample testing as a herd-screening tool for detection of bovine viral diarrhea virus persistently infected cattle. J Vet Diagn Invest 2000; 12:195-203. [PMID: 10826831 DOI: 10.1177/104063870001200301] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The study was conducted to develop methodology for least-cost strategies for using polymerase chain reaction (PCR)/probe testing of pooled blood samples to identify animals in a herd persistently infected with bovine viral diarrhea virus (BVDV). Cost was estimated for 5 protocols using Monte Carlo simulations for herd prevalences of BVDV persistent infection (BVDV-PI) ranging from 0.5% to 3%, assuming a cost for a PCR/probe test of $20. The protocol associated with the least cost per cow involved an initial testing of pools followed by repooling and testing of positive pools. For a herd prevalence of 1%, the least cost per cow was $2.64 (95% prediction interval = $1.72, $3.68), where pool sizes for the initial and repooled testing were 20 and 5 blood samples per pool, respectively. Optimization of the least cost for pooled-sample testing depended on how well a presumed prevalence of BVDV-PI approximated the true prevalence of BVDV infection in the herd. As prevalence increased beyond 3%, the least cost increased, thereby diminishing the competitive benefit of pooled testing. The protocols presented for sample pooling have general application to screening or surveillance using a sensitive diagnostic test to detect very low prevalence diseases or pathogens in flocks or herds.
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Affiliation(s)
- C A Muñoz-Zanzi
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA
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Evermann JF, Eriks IS. Diagnostic medicine: the challenge of differentiating infection from disease and making sense for the veterinary clinician. ADVANCES IN VETERINARY MEDICINE 1999; 41:25-38. [PMID: 9890007 PMCID: PMC7149316 DOI: 10.1016/s0065-3519(99)80006-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- J F Evermann
- Department of Veterinary Clinical Sciences, Washington State University, Pullman 99164, USA
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