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Pozo P, Bezos J, Romero B, Grau A, Nacar J, Saez JL, Minguez O, Alvarez J. Once bitten twice shy: Risk factors associated with bovine tuberculosis recurrence in Castilla y Leon, Spain. Res Vet Sci 2023; 159:72-80. [PMID: 37087923 DOI: 10.1016/j.rvsc.2023.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/04/2023] [Accepted: 04/15/2023] [Indexed: 04/25/2023]
Abstract
Persistence of bovine tuberculosis (bTB) in cattle herd remains a major challenge in disease elimination due to the ineffectual removal of all infected animals in a bTB breakdown. Characterization of herds with a higher probability of experiencing further bTB breakdowns can help to implement specific risk-based policies for disease control and eradication. Here, our aim was to identify herd- and breakdown-level risk factors in bTB infected herds in Castilla y Leon, Spain, associated with a decreased time to recurrence and an increased risk of recurrence using a mixed effects Cox proportional hazards model and a multivariable logistic regression model, respectively. Results revealed that location (province), herd size and number of incoming animals/contacts were good predictors of a decreased time to bTB recurrence and an increased risk of becoming a recurrent herd. Additionally, the duration of the previous outbreak and the number of IFN-γ herd-tests applied in it were associated with increased odds of (an early) recurrence. Risk factors identified here can be used for early identification of herds in which bTB eradication may be more challenging and that should thus be subjected to increased control efforts. The characterization of high-risk herds may help to minimize the risk of reinfection and emphasize early detection and removal of bTB positive animals in the herd.
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Affiliation(s)
- Pilar Pozo
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid, Spain; SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ciudad Real, Spain.
| | - Javier Bezos
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid, Spain; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid. Spain
| | - Beatriz Romero
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid, Spain; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid. Spain
| | - Anna Grau
- Dirección General de Producción Agropecuaria e Infraestructuras Agrarias, Consejería de Agricultura y Ganadería de la Junta de Castilla y León, Valladolid, Spain
| | - Jesus Nacar
- Dirección General de Producción Agropecuaria e Infraestructuras Agrarias, Consejería de Agricultura y Ganadería de la Junta de Castilla y León, Valladolid, Spain
| | - Jose Luis Saez
- Subdirección General de Sanidad e Higiene Animal y Trazabilidad, Dirección General de Sanidad de la Producción Agraria, Ministerio de Agricultura, Pesca y Alimentación, Madrid, Spain
| | - Olga Minguez
- Consejería de Sanidad de la Junta de Castilla y León, Valladolid, Spain
| | - Julio Alvarez
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid, Spain; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid. Spain
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Madden JM, McGrath G, Sweeney J, Murray G, Tratalos JA, More SJ. Spatio-temporal models of bovine tuberculosis in the Irish cattle population, 2012-2019. Spat Spatiotemporal Epidemiol 2021; 39:100441. [PMID: 34774256 DOI: 10.1016/j.sste.2021.100441] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 07/08/2021] [Accepted: 07/19/2021] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Bovine tuberculosis (bTB) is an important zoonotic disease which has serious and sometimes fatal effects on both human and non-human animals. In many countries it is endemic in the cattle population and has a considerable economic impact through losses in productivity and impacts on trade. The incidence rate in Ireland varies by herd and location and it is hoped that statistical disease-mapping models accounting for both spatio-temporal correlation and covariates might contribute towards explaining this variation. METHODS Ireland was divided into equally sized hexagons for computational efficiency (n = 997). Different spatio-temporal random-effects models (e.g. negative binomial Besag-York-Mollié) were explored, using comprehensive data from the national bTB eradication programme to examine the association between covariates and the number of bTB cattle. Leveraging a Bayesian framework, model parameter estimates were obtained using the integrated nested Laplace approximation (INLA) approach. Exceedance probabilities were calculated to identify spatial clusters of cases. RESULTS Models accounting for spatial correlation significantly improved model fit in comparison to non-spatial versions where independence between regions was assumed. In our final model at hexagon level, the number of cattle (IR = 1.142, CrI: 1.108 - 1.177 per 1000), the capture of badgers (IR = 5.951, CrI: 4.482 - 7.912), percentage of forest cover (IR = 1.031, CrI: 1.020 - 1.042) and number of farm fragments (IR = 1.012, CrI: 1.009 - 1.015 per 10 fragments) were all associated with an increased incidence of bTB. Habitat suitability for badgers, percentage of dairy herds and the number of cattle movements into the herd were not. As an epidemiological tool and to suggest future work, an interactive online dashboard was developed to monitor disease progression and disseminate results to the general public. CONCLUSION Accounting for spatial correlation is an important consideration in disease mapping applications and is often ignored in statistical models examining bTB risk factors. Over time, the same regions in Ireland generally show highest incidences of bTB and allocation of more resources to these areas may be needed to combat the disease. This study highlights national bTB incidence rates. Shifting from national level analysis to smaller geographical regions may help identify localised high-risk areas.
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Affiliation(s)
- Jamie M Madden
- Centre for Veterinary Epidemiology and Risk Analysis (CVERA), School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Guy McGrath
- Centre for Veterinary Epidemiology and Risk Analysis (CVERA), School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - James Sweeney
- Department of Mathematics and Statistics, University of Limerick, Limerick, Ireland
| | - Gerard Murray
- Department of Agriculture, Food and Marine, Drumshanbo Regional Veterinary Office, Derryhallagh, Drumshanbo, Co. Leitirm, Ireland
| | - Jamie A Tratalos
- Centre for Veterinary Epidemiology and Risk Analysis (CVERA), School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Simon J More
- Centre for Veterinary Epidemiology and Risk Analysis (CVERA), School of Veterinary Medicine, University College Dublin, Dublin, Ireland
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Menzies FD, McCormick CM, O'Hagan MJH, Collins SF, McEwan J, McGeown CF, McHugh GE, Hart CD, Stringer LA, Molloy C, Burns G, McBride SJ, Doyle LP, Courcier EA, McBride KR, McNair J, Thompson S, Corbett DM, Harwood RG, Trimble NA. Test and vaccinate or remove: Methodology and preliminary results from a badger intervention research project. Vet Rec 2021; 189:e248. [PMID: 33870503 DOI: 10.1002/vetr.248] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 12/22/2020] [Accepted: 02/21/2021] [Indexed: 01/01/2023]
Abstract
BACKGROUND In the British Isles, it is generally accepted that the Eurasian badger (Meles meles) plays a role in the maintenance of bovine tuberculosis (bTB) in cattle. Non-selective culling is the main intervention method deployed in controlling bTB in badgers along with smaller scale Bacillus Calmette-Guérin (BCG) vaccination areas. This paper describes the use of selective badger culling combined with vaccination in a research intervention trial. METHODS In Northern Ireland, a 100 km2 area was subjected to a test and vaccinate or remove (TVR) badger intervention over a 5-year period. Badgers were individually identified and tested on an annual basis. Physical characteristics and clinical samples were obtained from each unique badger capture event. RESULTS A total of 824 badgers were trapped with 1520 capture/sampling events. There were no cage-related injuries to the majority of badgers (97%). A low level of badger removal was required (4.1%-16.4% annually), while 1412 BCG vaccinations were administered. A statistically significant downward trend in the proportion of test positive badgers was observed. CONCLUSION This is the first project to clearly demonstrate the feasibility of cage side testing of badgers. The results provide valuable data on the logistics and resources required to undertake a TVR approach to control Mycobacterium bovis in badgers.
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Affiliation(s)
- Fraser D Menzies
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Carl M McCormick
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK.,Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, Northern Ireland, UK
| | - Maria J H O'Hagan
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Shane F Collins
- TVR Field Implementation Unit, Department of Agriculture, Environment and Rural Affairs, Newry, Northern Ireland, UK
| | - Jim McEwan
- Forest Service, Belvoir Park Forest, Belfast, Northern Ireland, UK
| | - Clare F McGeown
- TVR Field Implementation Unit, Department of Agriculture, Environment and Rural Affairs, Newry, Northern Ireland, UK
| | - Geraldine E McHugh
- TVR Field Implementation Unit, Department of Agriculture, Environment and Rural Affairs, Newry, Northern Ireland, UK
| | - Colin D Hart
- Enzootic Diseases and Animal Welfare Division, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Lesley A Stringer
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Colm Molloy
- Enzootic Diseases and Animal Welfare Division, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK.,Land and Property Services, Department of Finance, Belfast, Northern Ireland, UK
| | - Gareth Burns
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, Northern Ireland, UK
| | - Stewart J McBride
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, Northern Ireland, UK
| | - Liam P Doyle
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Emily A Courcier
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Kathryn R McBride
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - James McNair
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, Northern Ireland, UK
| | - Suzan Thompson
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, Northern Ireland, UK
| | - David M Corbett
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, Northern Ireland, UK
| | - Roland G Harwood
- Enzootic Diseases and Animal Welfare Division, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
| | - Nigel A Trimble
- Enzootic Diseases and Animal Welfare Division, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland, UK
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Kelly DJ, Mullen E, Good M. Bovine Tuberculosis: The Emergence of a New Wildlife Maintenance Host in Ireland. Front Vet Sci 2021; 8:632525. [PMID: 33842575 PMCID: PMC8027074 DOI: 10.3389/fvets.2021.632525] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/02/2021] [Indexed: 11/13/2022] Open
Abstract
Despite advances in herd management, tuberculosis (TB) continues to affect ~0. 5% of Ireland's national cattle herd annually. It is clear that any "final" eradication of TB in cattle will need to address all TB maintenance hosts in the same environment. In Ireland and the UK, European Badgers (Meles meles) are a known TB maintenance host, while deer are recognised as spillover hosts. However, deer have been identified as maintenance hosts in other countries and Sika deer, specifically, have been identified with TB in Ireland. We examined the power of cattle, badger and Sika deer densities (at the county level) to predict cattle TB-breakdowns in Ireland, at both the herd and the individual level, using data collected between 2000 and 2018. Our hypothesis was that any positive correlations between deer density and cattle TB-breakdowns would implicate deer as TB maintenance hosts. Using linear multiple regressions, we found positive correlations between deer density and cattle TB-breakdowns at both the herd and individual levels. Since Sika deer in County Wicklow are known to have TB, we ran further regressions against subsets of data which excluded individual Irish counties. Analyses excluding Wicklow data showed much weaker correlations between Sika deer density and cattle TB-breakdowns at both the herd and individual levels, suggesting that these correlations are strongest in County Wicklow. A similar effect for badger density was seen in County Leitrim. While locally high densities of Sika deer persist in Irish counties, we believe they should be considered an integral part of any TB-control programme for those areas.
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Affiliation(s)
- David J Kelly
- Discipline of Zoology, School of Natural Sciences, Trinity College Dublin, The University of Dublin, Dublin, Ireland
| | - Enda Mullen
- National Parks and Wildlife Service, Department of Housing, Local Government and Heritage, Dublin, Ireland
| | - Margaret Good
- Discipline of Zoology, School of Natural Sciences, Trinity College Dublin, The University of Dublin, Dublin, Ireland.,Independent Researcher and Private Consultant, Dun Laoghaire, Co. Dublin, Ireland
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Ciaravino G, Laranjo-González M, Casal J, Sáez-Llorente JL, Allepuz A. Most likely causes of infection and risk factors for tuberculosis in Spanish cattle herds. Vet Rec 2021; 189:e140. [PMID: 34297366 DOI: 10.1002/vetr.140] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/17/2020] [Accepted: 01/26/2021] [Indexed: 12/30/2022]
Abstract
INTRODUCTION This study aims to assess the most likely causes of Bovine tuberculosis (bTB) breakdowns in Spanish cattle herds and to identify the main risk factors at farm-level. METHODS Causes of bTB breakdowns were assessed through a qualitative risk-assessment based on decision-trees by analysing surveillance data from 3819 bTB breakdowns detected during 2014-2016. Results were compared to veterinary officers' (VO) opinions. Risk factors were identified through a case-control study with data from 196 bTB cases and 160 controls collected during 2014-2018. RESULTS The decision tree analysis identified residual infections and interactions with wildlife as the most frequent causes of breakdowns (36% each), followed by purchasing infected cattle (14%). These results were not supported by VOs' opinions. According to the regression models, the risk of bTB increased by sharing pastures (odds ratios [OR] = 2.7; 95% confidence interval [CI] = 1.6-4.4) and by increasing inwards cattle movements. The presence of wildlife reservoirs represented a significant risk for extensively-managed farms if other cattle farms are situated within a one-kilometre radius (OR = 2.3; 95% CI = 1.1-5.1). DISCUSSION To prevent bTB breakdowns, efforts should be devoted to decrease the likelihood of residual infections and improve farm biosecurity. The adoption of biosecurity measures might be influenced by farmers' perceptions, which should be carefully evaluated to ensure the effectiveness of such strategies.
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Affiliation(s)
- Giovanna Ciaravino
- Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Minerva Laranjo-González
- Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Jordi Casal
- Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain.,Animal Health Research Center IRTA-CReSA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
| | | | - Alberto Allepuz
- Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain.,Animal Health Research Center IRTA-CReSA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
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Arnold ME, Courcier EA, Stringer LA, McCormick CM, Pascual-Linaza AV, Collins SF, Trimble NA, Ford T, Thompson S, Corbett D, Menzies FD. A Bayesian analysis of a Test and Vaccinate or Remove study to control bovine tuberculosis in badgers (Meles meles). PLoS One 2021; 16:e0246141. [PMID: 33508004 PMCID: PMC7842978 DOI: 10.1371/journal.pone.0246141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 01/13/2021] [Indexed: 12/15/2022] Open
Abstract
A novel five year Test and Vaccinate or Remove (TVR) wildlife research intervention project in badgers (Meles meles) commenced in 2014 in a 100km2 area of Northern Ireland. It aimed to increase the evidence base around badgers and bovine TB and help create well-informed and evidence-based strategies to address the issue of cattle-to-cattle spread and spread between cattle and badgers. It involved real-time trap-side testing of captured badgers and vaccinating those that tested negative for bTB (BadgerBCG-BCG Danish 1331) and removal of those that tested bTB positive using the Dual-Path Platform VetTB test (DPP) for cervids (Chembio Diagnostic Systems, Medford, NY USA). Four diagnostic tests were utilised within the study interferon gamma release assay (IGRA), culture (clinical samples and post mortem), DPP using both whole blood and DPP using serum. BCG Sofia (SL222) was used in the final two years because of supply issues with BadgerBCG. Objectives for this study were to evaluate the performance of the DPP in field conditions and whether any trend was apparent in infection prevalence over the study period. A Bayesian latent class model of diagnostic test evaluation in the absence of a gold standard was applied to the data. Temporal variation in the sensitivity of DPP and interferon gamma release assay (IGRA) due to the impact of control measures was investigated using logistic regression and individual variability was assessed. Bayesian latent class analysis estimated DPP with serum to have a sensitivity of 0.58 (95% CrI: 0.40-0.76) and specificity of 0.97 (95% CrI: 0.95-0.98). The DPP with whole blood showed a higher sensitivity (0.69 (95% CrI: 0.48-0.88)) but similar specificity (0.98 (95% Crl: 0.96-0.99)). The change from BCG Danish to BCG Sofia significantly impacted on DPP serum test characteristics. In addition, there was weak evidence of increasing sensitivity of IGRA over time and differences in DPP test sensitivity between adults and cubs. An exponential decline model was an appropriate representation of the infection prevalence over the 5 years, with a starting prevalence of 14% (95% CrI: 0.10-0.20), and an annual reduction of 39.1% (95% CrI: 26.5-50.9). The resulting estimate of infection prevalence in year 5 of the study was 1.9% (95% CrI: 0.8-3.8). These results provide field evidence of a statistically significant reduction in badger TB prevalence supporting a TVR approach to badger intervention. They give confidence in the reliability and reproducibility in the DPP Whole Blood as a real time trap-side diagnostic test for badgers, and describe the effect of vaccination and reduced infection prevalence on test characteristics.
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Affiliation(s)
- Mark E. Arnold
- Animal and Plant Health Agency Sutton Bonington, Sutton Bonington, Loughborough, England
| | - Emily A. Courcier
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland
| | - Lesley A. Stringer
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland
| | - Carl M. McCormick
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stormont, Belfast, Northern Ireland
| | - Ana V. Pascual-Linaza
- Animal and Plant Health Agency Sutton Bonington, Sutton Bonington, Loughborough, England
| | - Shane F. Collins
- TVR Field Implementation Unit, Department of Agriculture, Environment and Rural Affairs, Newry, Northern Ireland
| | - Nigel A. Trimble
- TVR Field Implementation Unit, Department of Agriculture, Environment and Rural Affairs, Newry, Northern Ireland
| | - Tom Ford
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stormont, Belfast, Northern Ireland
| | - Suzan Thompson
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stormont, Belfast, Northern Ireland
| | - David Corbett
- Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stormont, Belfast, Northern Ireland
| | - Fraser D. Menzies
- Veterinary Epidemiology Unit, Department of Agriculture, Environment and Rural Affairs, Belfast, Northern Ireland
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Byrne AW, Barrett D, Breslin P, Madden JM, O’Keeffe J, Ryan E. Bovine Tuberculosis ( Mycobacterium bovis) Outbreak Duration in Cattle Herds in Ireland: A Retrospective Observational Study. Pathogens 2020; 9:E815. [PMID: 33027882 PMCID: PMC7650827 DOI: 10.3390/pathogens9100815] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 11/28/2022] Open
Abstract
Bovine tuberculosis (bTB) outbreaks, caused by Mycobacterium bovis infection, are a costly animal health challenge. Understanding factors associated with the duration of outbreaks, known as breakdowns, could lead to better disease management policy development. We undertook a retrospective observational study (2012-2018) and employed Finite Mixture Models (FMM) to model the outcome parameter, and to investigate how factors were associated with duration for differing subpopulations identified. In addition to traditional risk factors (e.g., herd size, bTB history), we also explored farm geographic area, parcels/farm fragmentation, metrics of intensity via nitrogen loading, and whether herds were designated controlled beef finishing units (CBFU) as potential risk factors for increased duration. The final model fitted log-normal distributions, with two latent classes (k) which partitioned the population into a subpopulation around the central tendency of the distribution, and a second around the tails of the distribution. The latter subpopulation included longer breakdowns of policy interest. Increasing duration was positively associated with recent (<3 years) TB history and the number of reactors disclosed, (log) herd size, beef herd-type relative to other herd types, number of land parcels, area, being designated a CBFU ("feedlot") and having high annual inward cattle movements within the "tails" subpopulation. Breakdown length was negatively associated with the year of commencement of breakdown (i.e., a decreasing trend) and non-significantly with the organic nitrogen produced on the farm (N kg/hectare), a measure of stocking density. The latter finding may be due to confounding effects with herd size and area. Most variables contributed only moderately to explaining variation in breakdown duration, that is, they had moderate size effects on duration. Herd-size and CBFU had greater effect sizes on the outcome. The findings contribute to evidence-based policy formation in Ireland.
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Affiliation(s)
- Andrew W. Byrne
- One-Health Scientific Support Unit, Surveillance, Animal by-products, and TSEs (SAT) Division, Department of Agriculture, Food and the Marine, Agriculture House, Dublin 2 D02 WK12, Ireland;
| | - Damien Barrett
- One-Health Scientific Support Unit, Surveillance, Animal by-products, and TSEs (SAT) Division, Department of Agriculture, Food and the Marine, Agriculture House, Dublin 2 D02 WK12, Ireland;
| | - Philip Breslin
- Ruminant Animal Health Division, Department of Agriculture, Food and the Marine, Backweston, Co. Kildare W23 VW2C, Ireland; (P.B.); (J.O.)
| | - Jamie M. Madden
- Centre for Veterinary Epidemiology and Risk Analysis (CVERA), School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4 D04 W6F6, Ireland;
| | - James O’Keeffe
- Ruminant Animal Health Division, Department of Agriculture, Food and the Marine, Backweston, Co. Kildare W23 VW2C, Ireland; (P.B.); (J.O.)
| | - Eoin Ryan
- Ruminant Animal Health Division, Department of Agriculture, Food and the Marine, Backweston, Co. Kildare W23 VW2C, Ireland; (P.B.); (J.O.)
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Milne G, Allen A, Graham J, Lahuerta-Marin A, McCormick C, Presho E, Reid N, Skuce R, Byrne AW. Bovine tuberculosis breakdown duration in cattle herds: an investigation of herd, host, pathogen and wildlife risk factors. PeerJ 2020; 8:e8319. [PMID: 32117602 PMCID: PMC7003687 DOI: 10.7717/peerj.8319] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 11/29/2019] [Indexed: 11/20/2022] Open
Abstract
Background Despite rigorous controls placed on herds which disclose ante-mortem test positive cattle to bovine tuberculosis, caused by the infection of Mycobacterium bovis, many herds in Northern Ireland (NI) experience prolonged breakdowns. These herds represent a considerable administrative and financial burden to the State and farming community. Methods A retrospective observational study was conducted to better understand the factors associated with breakdown duration, which was modelled using both negative binomial and ordinal regression approaches. Results Six explanatory variables were important predictors of breakdown length in both models; herd size, the number of reactors testing positive in the initial SICCT test, the presence of a lesioned animal at routine slaughter (LRS), the count of M. bovis genotypes during the breakdown (MLVA richness), the local herd-level bTB prevalence, and the presence of herds linked via management factors (associated herds). We report that between 2008 and 2014, mean breakdown duration in NI was 226 days (approx. seven months; median: 188 days). In the same period, however, more than 6% of herds in the region remained under movement restriction for more than 420 days (13 months); almost twice as long as the mean. The MLVA richness variable was a particularly important predictor of breakdown duration. We contend that this variable primarily represents a proxy for beef fattening herds, which can operate by purchasing cattle and selling animals straight to slaughter, despite prolonged trading restrictions. For other herd types, the model supports the hypothesis that prolonged breakdowns are a function of both residual infection within the herd, and infection from the environment (e.g. infected wildlife, contiguous herds and/or a contaminated environment). The impact of badger density on breakdown duration was assessed by including data on main sett (burrow) density. Whilst a positive association was observed in the univariate analysis, confounding with other variables means that the contribution of badgers to prolonged breakdowns was not clear from our study. We do not fully reject the hypothesis that badgers are implicated in prolonging bTB breakdowns via spillback infection, but given our results, we posit that increased disease risk from badgers is unlikely to simply be a function of increasing badger density measured using sett metrics.
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Affiliation(s)
- Georgina Milne
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom
| | - Adrian Allen
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom
| | - Jordon Graham
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom
| | - Angela Lahuerta-Marin
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom
| | - Carl McCormick
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom.,Department of Agriculture, Environment, and Rural Affairs, Coleraine, United Kingdom
| | - Eleanor Presho
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom
| | - Neil Reid
- School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Robin Skuce
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom
| | - Andrew W Byrne
- Veterinary Sciences Division, Agri-food and Biosciences Institute, Belfast, United Kingdom.,School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom.,One-Health Scientific Support Unit, Department of Agriculture, Food and the Marine, Dublin, Ireland
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9
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Clegg TA, Doyle M, Ryan E, More SJ, Gormley E. Characteristics of Mycobacterium bovis infected herds tested with the interferon-gamma assay. Prev Vet Med 2019; 168:52-59. [PMID: 31097123 DOI: 10.1016/j.prevetmed.2019.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 01/09/2023]
Abstract
The IFN-γ (interferon gamma) assay is used in Ireland as an ancillary diagnostic test to the single intradermal comparative tuberculin test (SICTT) to maximise the detection of Mycobacterium bovis infected animals (bTB) in cattle herds. Understanding the relationships between herd and animal risk factors and IFN-γ test results is critical to enable the development and evaluation of policy measures on how best to use the test. In this study, we set out to characterise Irish herds with IFN-γ test positive animals in terms of herd size, number of SICTT reactors and number of IFN-γ positive tests, and to evaluate the IFN-γ test in terms of the test cut-off values. The results showed that larger herds with more SICTT reactors were likely to have more IFN-γ positives in the herd, and herds with an IFN-γ test positive animal that was also positive for bTB lesions at post-mortem had higher numbers of IFN-γ positive animals in the herd. Raising the cut-off values for the IFN-γ test only marginally decreased the combined sensitivity of the IFN-γ and the SICTT for diagnosis of bTB lesioned animals. The analysis has provided valuable information on the performance of the IFN-γ test as it is used under current bTB infection levels in Ireland.
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Affiliation(s)
- T A Clegg
- Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
| | - M Doyle
- Tuberculosis Diagnostics and Immunology Research Laboratory, School of Veterinary Medicine, University College Dublin, UCD, Belfield, Dublin 4, Ireland.
| | - E Ryan
- Department of Agriculture, Food & the Marine, Backweston, Co. Kildare, Ireland.
| | - S J More
- Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
| | - E Gormley
- Tuberculosis Diagnostics and Immunology Research Laboratory, School of Veterinary Medicine, University College Dublin, UCD, Belfield, Dublin 4, Ireland.
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Doyle R, Clegg TA, McGrath G, Tratalos J, Barrett D, Lee A, More SJ. The bovine tuberculosis cluster in north County Sligo during 2014-16. Ir Vet J 2018; 71:24. [PMID: 30534362 PMCID: PMC6262969 DOI: 10.1186/s13620-018-0135-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/15/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bovine tuberculosis (bTB, caused by infection with Mycobacterium bovis) is endemic in the Irish cattle population, and the subject of a national eradication programme since the late 1950s. During 2014, a substantial area-level bTB outbreak developing in north County Sligo, necessitating the need for an enhanced response. This paper describes this outbreak, the response that was undertaken and some lessons learned. RESULTS In the north Sligo area between 2014 and 2016, 23 (31.9%) of restricted herds had 4 or more reactors to the single intradermal comparative tuberculin test (SICTT)/animals with bTB lesions disclosed during the restriction, and the majority (55.5%) of test-positive animals were identified as standard reactors to the SICTT. The herds restricted during 2014-16 were typically larger than other herds in the study area and introduced more animals during 2013. M. bovis was also detected in local badgers, but not deer. CONCLUSION This paper describes a substantial outbreak in north County Sligo over a 3-year period. A coordinated area-based approach was a key feature of the outbreak, and substantial resources were applied to bring the outbreak under control. No definitive source was identified, nor reasons why a substantial number of herds were infected over a relatively short period. A coordinated regional approach was taken, and a number of lessons were learned including the need for urgency, for a team-based approach, for a consistent message when dealing with the public, for an area-based approach, for a degree of flexibility for the breakdown manager, and for molecular tools to assist in answering key questions relating to the source and spread of M. bovis to many herds during this bTB outbreak.
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Affiliation(s)
- Rob Doyle
- Department of Agriculture, Food and the Marine, Backweston Administration Building, Stacumny Lane, Celbridge, Co. Kildare W23 X3PH Ireland
| | - Tracy A. Clegg
- Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, D04 W6F6 Ireland
| | - Guy McGrath
- Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, D04 W6F6 Ireland
| | - Jamie Tratalos
- Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, D04 W6F6 Ireland
| | - Damien Barrett
- Department of Agriculture, Food and the Marine, Backweston Administration Building, Stacumny Lane, Celbridge, Co. Kildare W23 X3PH Ireland
| | - Ada Lee
- Cyberport, Pokfulam, Hong Kong Island, Hong Kong
| | - Simon J. More
- Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, D04 W6F6 Ireland
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