1
|
Arzt J, Sanderson MW, Stenfeldt C. Foot-and-Mouth Disease. Vet Clin North Am Food Anim Pract 2024; 40:191-203. [PMID: 38462419 DOI: 10.1016/j.cvfa.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024] Open
Abstract
Foot-and-mouth disease (FMD) is a viral infection of livestock that is an important determinant of global trade in animal products. The disease causes a highly contagious vesicular syndrome of cloven-hoofed animals. Successful control of FMD is dependent upon early detection and recognition of the clinical signs, followed by appropriate notification and response of responsible government entities. Awareness of the clinical signs of FMD amongst producers and veterinary practitioners is therefore the key in protecting US agriculture from the catastrophic impacts of an FMD outbreak. This review summarizes key clinical and epidemiologic features of FMD from a US perspective.
Collapse
Affiliation(s)
- Jonathan Arzt
- Foreign Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, PO Box 848, Greenport, NY 11944, USA
| | - Michael W Sanderson
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Center for Outcomes Research and Epidemiology, 1800 Denison Avenue, Manhattan, KS 66502, USA
| | - Carolina Stenfeldt
- Foreign Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, PO Box 848, Greenport, NY 11944, USA; Department of Diagnostic Medicine/Pathobiology, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66502, USA.
| |
Collapse
|
2
|
Sirdar MM, Fosgate GT, Blignaut B, Heath L, Lazarus DD, Mampane RL, Rikhotso OB, Du Plessis B, Gummow B. A comparison of risk factor investigation and experts' opinion elicitation analysis for identifying foot-and-mouth disease (FMD) high-risk areas within the FMD protection zone of South Africa (2007-2016). Prev Vet Med 2024; 226:106192. [PMID: 38564991 DOI: 10.1016/j.prevetmed.2024.106192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/26/2024] [Accepted: 03/24/2024] [Indexed: 04/04/2024]
Abstract
Foot-and-mouth disease is a controlled disease in accordance with the South African Animal Diseases Act (Act 35 of 1984). The country was classified by the World Organisation for Animal Health (WOAH) as having a FMD free zone without vaccination in 1996. However, this status was suspended in 2019 due to a FMD outbreak outside the controlled zones. FMD control in South Africa includes animal movement restrictions placed on cloven-hoofed species and products, prophylactic vaccination of cattle, clinical surveillance of susceptible species, and disease control fencing to separate livestock from wildlife reservoirs. The objectives of this study were to evaluate differences in identifying high-risk areas for FMD using risk factor and expert opinion elicitation analysis. Differences in risk between FMD introduction and FMD spread within the FMD protection zone with vaccination (PZV) of South Africa (2007-2016) were also investigated. The study was conducted in the communal farming area of the FMD PZV, which is adjacent to wildlife reserves and characterised by individual faming units. Eleven risk factors that were considered important for FMD occurrence and spread were used to build a weighted linear combination (WLC) score based on risk factor data and expert opinion elicitation. A multivariable conditional logistic regression model was also used to calculate predicted probabilities of a FMD outbreak for all dip-tanks within the study area. Smoothed Bayesian kriged maps were generated for 11 individual risk factors, overall WLC scores for FMD occurrence and spread and for predicted probabilities of a FMD outbreak based on the conditional logistic regression model. Descriptively, vaccine matching was believed to have a great influence on both FMD occurrence and spread. Expert opinion suggested that FMD occurrence was influenced predominantly by proximity to game reserves and cattle density. Cattle populations and vaccination practices were considered most important for FMD spread. Highly effective cattle inspections were observed within areas that previously reported FMD outbreaks, indicating the importance of cattle inspection (surveillance) as a necessary element of FMD outbreak detection. The multivariable conditional logistic regression analysis, which was consistent with expert opinion elicitation; identified three factors including cattle population density (OR 3.87, 95% CI 1.47-10.21) and proximities to game reserve fences (OR 0.82, 95% CI 0.73-0.92) and rivers (OR 1.04, 95% CI 1.01-1.07) as significant factors for reported FMD outbreaks. Regaining and maintaining an FMD-free status without vaccination requires frequent monitoring of high-risk areas and designing targeted surveillance.
Collapse
Affiliation(s)
- M M Sirdar
- Epidemiology Section, Department of Production Animal Studies, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort 0110, South Africa; Onderstepoort Veterinary Research, Agricultural Research Council, Onderstepoort 0110, South Africa; World Organisation for Animal Health, WOAH Sub-Regional Representation for Southern Africa, Gaborone, Botswana.
| | - G T Fosgate
- Epidemiology Section, Department of Production Animal Studies, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort 0110, South Africa
| | - B Blignaut
- Epidemiology Section, Department of Production Animal Studies, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort 0110, South Africa; Onderstepoort Veterinary Research, Agricultural Research Council, Onderstepoort 0110, South Africa
| | - L Heath
- Onderstepoort Veterinary Research, Agricultural Research Council, Onderstepoort 0110, South Africa
| | - D D Lazarus
- Epidemiology Section, Department of Production Animal Studies, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort 0110, South Africa; Onderstepoort Veterinary Research, Agricultural Research Council, Onderstepoort 0110, South Africa
| | - R L Mampane
- Limpopo Veterinary Services, Department of Agriculture and Rural Development, Polokwane, Limpopo, South Africa
| | - O B Rikhotso
- Mpumalanga Veterinary Services, Department of Agriculture, Rural Development, Land and Environmental Affairs, Mpumalanga, South Africa
| | - B Du Plessis
- Mpumalanga Veterinary Services, Department of Agriculture, Rural Development, Land and Environmental Affairs, Mpumalanga, South Africa
| | - B Gummow
- Epidemiology Section, Department of Production Animal Studies, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort 0110, South Africa; College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| |
Collapse
|
3
|
Seibel RL, Meadows AJ, Mundt C, Tildesley M. Modeling target-density-based cull strategies to contain foot-and-mouth disease outbreaks. PeerJ 2024; 12:e16998. [PMID: 38436010 PMCID: PMC10909358 DOI: 10.7717/peerj.16998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 02/02/2024] [Indexed: 03/05/2024] Open
Abstract
Total ring depopulation is sometimes used as a management strategy for emerging infectious diseases in livestock, which raises ethical concerns regarding the potential slaughter of large numbers of healthy animals. We evaluated a farm-density-based ring culling strategy to control foot-and-mouth disease (FMD) in the United Kingdom (UK), which may allow for some farms within rings around infected premises (IPs) to escape depopulation. We simulated this reduced farm density, or "target density", strategy using a spatially-explicit, stochastic, state-transition algorithm. We modeled FMD spread in four counties in the UK that have different farm demographics, using 740,000 simulations in a full-factorial analysis of epidemic impact measures (i.e., culled animals, culled farms, and epidemic length) and cull strategy parameters (i.e., target farm density, daily farm cull capacity, and cull radius). All of the cull strategy parameters listed above were drivers of epidemic impact. Our simulated target density strategy was usually more effective at combatting FMD compared with traditional total ring depopulation when considering mean culled animals and culled farms and was especially effective when daily farm cull capacity was low. The differences in epidemic impact measures among the counties are likely driven by farm demography, especially differences in cattle and farm density. To prevent over-culling and the associated economic, organizational, ethical, and psychological impacts, the target density strategy may be worth considering in decision-making processes for future control of FMD and other diseases.
Collapse
Affiliation(s)
- Rachel L. Seibel
- Mathematics Institute, University of Warwick, Coventry, West Midlands, United Kingdom
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States
| | - Amanda J. Meadows
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States
- Ginkgo Bioworks, San Bruno, California, United States
| | - Christopher Mundt
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States
| | - Michael Tildesley
- Mathematics Institute, University of Warwick, Coventry, West Midlands, United Kingdom
| |
Collapse
|
4
|
Exploring the predictive capability of machine learning models in identifying foot and mouth disease outbreak occurrences in cattle farms in an endemic setting of Thailand. Prev Vet Med 2022; 207:105706. [DOI: 10.1016/j.prevetmed.2022.105706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 06/09/2022] [Accepted: 07/01/2022] [Indexed: 11/20/2022]
|
5
|
Haoran W, Jianhua X, Maolin O, Hongyan G, Jia B, Li G, Xiang G, Hongbin W. Assessment of foot-and-mouth disease risk areas in mainland China based spatial multi-criteria decision analysis. BMC Vet Res 2021; 17:374. [PMID: 34872574 PMCID: PMC8647368 DOI: 10.1186/s12917-021-03084-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 11/16/2021] [Indexed: 12/01/2022] Open
Abstract
Background Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals. As a transboundary animal disease, the prevention and control of FMD are important. This study was based on spatial multi-criteria decision analysis (MCDA) to assess FMD risk areas in mainland China. Ten risk factors were identified for constructing risk maps by scoring, and the analytic hierarchy process (AHP) was used to calculate the criteria weights of all factors. Different risk factors had different units and attributes, and fuzzy membership was used to standardize the risk factors. The weighted linear combination (WLC) and one-at-a-time (OAT) were used to obtain risk and uncertainty maps as well as to perform sensitivity analysis. Results Four major risk areas were identified in mainland China, including western (parts of Xinjiang and Tibet), southern (parts of Yunnan, Guizhou, Guangxi, Sichuan and Guangdong), northern (parts of Gansu, Ningxia and Inner Mongolia), and eastern (parts of Hebei, Henan, Anhui, Jiangsu and Shandong). Spring is the main season for FMD outbreaks. Risk areas were associated with the distance to previous outbreak points, grazing areas and cattle density. Receiver operating characteristic (ROC) analysis indicated that the risk map had good predictive power (AUC=0.8634). Conclusions These results can be used to delineate FMD risk areas in mainland China, and veterinary services can adopt the targeted preventive measures and control strategies. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-021-03084-5.
Collapse
Affiliation(s)
- Wang Haoran
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Xiao Jianhua
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Ouyang Maolin
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Gao Hongyan
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Bie Jia
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Gao Li
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Gao Xiang
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China
| | - Wang Hongbin
- Department of Veterinary Surgery, Northeast Agricultural University, Harbin, Heilongjiang, 150030, PR China.
| |
Collapse
|
6
|
Spatial distribution of foot-and-mouth disease (FMD) outbreaks in South Africa (2005-2016). Trop Anim Health Prod 2021; 53:376. [PMID: 34181093 DOI: 10.1007/s11250-021-02807-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 06/04/2021] [Indexed: 10/21/2022]
Abstract
Foot-and-mouth disease (FMD) is a transboundary animal disease that has negative socioeconomic consequences including impacts on food security. In South Africa, FMD outbreaks in communal farming communities cause major livestock and human livelihood concerns; they raise apprehensions about the effectiveness of FMD control measures within the FMD protection areas. This study aimed to identify high-risk areas for FMD outbreaks at the human/domestic animal/wildlife interface of South Africa. Cuzick-Edwards tests and Kulldorff scan statistics were used to detect spatial autocorrelation and spatial-temporal clusters of FMD outbreaks for the years 2005-2016.Four high-risk clusters were identified and the spatial distribution of outbreaks in cattle were closer to game reserve fences and consistent with wildlife contacts as a main contributor of FMD occurrence. Strategic allocation of resources, focused control measures, and cooperation between the affected provinces are recommended to reduce future outbreaks. Further research is necessary to design cost-effective control strategies for FMD.
Collapse
|
7
|
Patyk KA, McCool-Eye MJ, South DD, Burdett CL, Maroney SA, Fox A, Kuiper G, Magzamen S. Modelling the domestic poultry population in the United States: A novel approach leveraging remote sensing and synthetic data methods. GEOSPATIAL HEALTH 2020; 15. [PMID: 33461269 DOI: 10.4081/gh.2020.913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/27/2020] [Indexed: 06/12/2023]
Abstract
Comprehensive and spatially accurate poultry population demographic data do not currently exist in the United States; however, these data are critically needed to adequately prepare for, and efficiently respond to and manage disease outbreaks. In response to absence of these data, this study developed a national-level poultry population dataset by using a novel combination of remote sensing and probabilistic modelling methodologies. The Farm Location and Agricultural Production Simulator (FLAPS) (Burdett et al., 2015) was used to provide baseline national-scale data depicting the simulated locations and populations of individual poultry operations. Remote sensing methods (identification using aerial imagery) were used to identify actual locations of buildings having the characteristic size and shape of commercial poultry barns. This approach was applied to 594 U.S. counties with > 100,000 birds in 34 states based on the 2012 U.S. Department of Agriculture (USDA), National Agricultural Statistics Service (NASS), Census of Agriculture (CoA). The two methods were integrated in a hybrid approach to develop an automated machine learning process to locate commercial poultry operations and predict the number and type of poultry for each operation across the coterminous United States. Validation illustrated that the hybrid model had higher locational accuracy and more realistic distribution and density patterns when compared to purely simulated data. The resulting national poultry population dataset has significant potential for application in animal disease spread modelling, surveillance, emergency planning and response, economics, and other fields, providing a versatile asset for further agricultural research.
Collapse
Affiliation(s)
- Kelly A Patyk
- United States Department of Agriculture, Animal Plant and Health Inspection Service, Veterinary Services, Strategy and Policy, Center for Epidemiology and Animal Health.
| | - Mary J McCool-Eye
- United States Department of Agriculture, Animal Plant and Health Inspection Service, Veterinary Services, Strategy and Policy, Center for Epidemiology and Animal Health.
| | - David D South
- United States Department of Agriculture, Animal Plant and Health Inspection Service, Veterinary Services, Strategy and Policy, Center for Epidemiology and Animal Health.
| | - Christopher L Burdett
- Colorado State University, Department of Environmental and Radiological Health Sciences, Fort Collins, CO.
| | - Susan A Maroney
- Colorado State University, Department of Environmental and Radiological Health Sciences, Fort Collins, CO.
| | - Andrew Fox
- United States Department of Agriculture, Animal Plant and Health Inspection Service, Veterinary Services, Strategy and Policy, Center for Epidemiology and Animal Health.
| | - Grace Kuiper
- Colorado State University, Department of Environmental and Radiological Health Sciences, Fort Collins, CO.
| | - Sheryl Magzamen
- Colorado State University, Department of Environmental and Radiological Health Sciences, Fort Collins, CO.
| |
Collapse
|
8
|
Sangrat W, Thanapongtharm W, Poolkhet C. Identification of risk areas for foot and mouth disease in Thailand using a geographic information system-based multi-criteria decision analysis. Prev Vet Med 2020; 185:105183. [PMID: 33153767 DOI: 10.1016/j.prevetmed.2020.105183] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 10/14/2020] [Accepted: 10/16/2020] [Indexed: 10/23/2022]
Abstract
In our study, we used geographic information system (GIS)-based multi-criteria decision analysis (MCDA) to predict suitable areas for foot and mouth disease (FMD) occurrence in Thailand. Eleven experts evaluated 10 spatial risk factors associated with the occurrence and spread of FMD in Thailand during 2014-2015. The analytic hierarchy process was used to conduct problem structuring and prioritising of pairwise comparisons with criterion weighting. Important spatial risk factors were converted to geographical layers using standardised fuzzy membership. Thus, weight linear combination was used to combine and create suitability and uncertainty maps as well as to perform sensitivity analysis. We identified areas in northern, north-eastern, western, and central Thailand as hotspots of FMD occurrence. In the predictive map, the suitable areas presented a moderate degree of agreement with those after FMD outbreaks in the year 2016 (AUC = 0.71, 95 %CI: 0.68-0.75). In conclusion, GIS-based MCDA mapping well supported veterinary services in identifying hotspot areas of FMD occurrence in Thailand. This tool was very useful for disease surveillance.
Collapse
Affiliation(s)
- Waratida Sangrat
- Section of Epidemiology, Department of Veterinary Public Health, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand; Department of Livestock Development, Bangkok, 10400, Thailand
| | | | - Chaithep Poolkhet
- Section of Epidemiology, Department of Veterinary Public Health, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
| |
Collapse
|
9
|
van Andel M, Tildesley MJ, Gates MC. Challenges and opportunities for using national animal datasets to support foot-and-mouth disease control. Transbound Emerg Dis 2020; 68:1800-1813. [PMID: 32986919 DOI: 10.1111/tbed.13858] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 11/29/2022]
Abstract
National level databases of animal numbers, locations and movements provide the essential foundations for disease preparedness, outbreak investigations and control activities. These activities are particularly important for managing and mitigating the risks of high-impact transboundary animal disease outbreaks such as foot-and-mouth disease (FMD), which can significantly affect international trade access and domestic food security. In countries where livestock production systems are heavily subsidized by the government, producers are often required to provide detailed animal movement and demographic data as a condition of business. In the remaining countries, it can be difficult to maintain these types of databases and impossible to estimate the extent of missing or inaccurate information due to the absence of gold standard datasets for comparison. Consequently, competent authorities are often required to make decisions about disease preparedness and control based on available data, which may result in suboptimal outcomes for their livestock industries. It is important to understand the limitations of poor data quality as well as the range of methods that have been developed to compensate in both disease-free and endemic situations. Using FMD as a case example, this review first discusses the different activities that competent authorities use farm-level animal population data for to support (1) preparedness activities in disease-free countries, (2) response activities during an acute outbreak in a disease-free country, and (3) eradication and control activities in an endemic country. We then discuss (4) data requirements needed to support epidemiological investigations, surveillance, and disease spread modelling both in disease-free and endemic countries.
Collapse
Affiliation(s)
- Mary van Andel
- Ministry for Primary Industries, Operations Branch, Diagnostic and Surveillance Services Directorate, Wallaceville, New Zealand
| | - Michael J Tildesley
- School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry, UK
| | - M Carolyn Gates
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
| |
Collapse
|
10
|
Hayama Y, Firestone SM, Stevenson MA, Yamamoto T, Nishi T, Shimizu Y, Tsutsui T. Reconstructing a transmission network and identifying risk factors of secondary transmissions in the 2010 foot-and-mouth disease outbreak in Japan. Transbound Emerg Dis 2019; 66:2074-2086. [PMID: 31131968 DOI: 10.1111/tbed.13256] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 11/27/2022]
Abstract
Research aimed at understanding transmission networks, representing a network of "who infected whom" for an infectious disease outbreak, have been actively conducted in recent years. Transmission network models incorporating epidemiological and genetic data are valuable for elucidating disease transmission pathways. In this study, we reconstructed the transmission network of the foot-and-mouth disease (FMD) epidemic in Japan in 2010, and explored farm-level risk factors associated with increased risk of secondary transmission. A published, systematic Bayesian transmission network model was applied to epidemiological data of 292 infected farms and whole genome sequence data of 104 of the infected farms. This model can make inferences for known infected farms even lacking genetic data. After estimating the consensus network, the accuracy of the network was examined by comparison with epidemiological data. Then, risk factors inferred to have been sources of secondary transmission were explored using zero-inflated Poisson regression model. As far as we are aware, this study represents the largest FMD outbreak transmission network to be published by such means combining epidemiological and genetic data. The consensus network reasonably generated the epidemiological links, which were estimated from the actual epidemiological investigation. Among 292 farms, 101 farms (35%) were inferred to have been the sources of secondary transmission, and amongst these farms, the median number of secondary cases was 2 (min:1-max:18) farms. The farm-type (small and large -sized pig farms), the number of days from onset to notification, and the number of susceptible farms within a 1-km radius were significantly associated with secondary transmission. Transmission network modelling enabled inference of the connections between infected farms during the FMD epidemic and identified important factors for controlling the risk of secondary transmission. This study demonstrated that the predominant susceptible species held on a farm, farm size, and animal density were associated with increased onwards transmission.
Collapse
Affiliation(s)
- Yoko Hayama
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Japan
| | - Simon M Firestone
- Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, Asia-Pacific Centre for Animal Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Mark A Stevenson
- Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, Asia-Pacific Centre for Animal Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Takehisa Yamamoto
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Japan
| | - Tatsuya Nishi
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
| | - Yumiko Shimizu
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Japan
| | - Toshiyuki Tsutsui
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Japan
| |
Collapse
|
11
|
Souley Kouato B, De Clercq K, Abatih E, Dal Pozzo F, King DP, Thys E, Marichatou H, Saegerman C. Review of epidemiological risk models for foot-and-mouth disease: Implications for prevention strategies with a focus on Africa. PLoS One 2018; 13:e0208296. [PMID: 30543641 PMCID: PMC6292601 DOI: 10.1371/journal.pone.0208296] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 11/15/2018] [Indexed: 11/18/2022] Open
Abstract
Foot-and-mouth disease (FMD) is a highly infectious transboundary disease that affects domestic and wild cloven-hoofed animal species. The aim of this review was to identify and critically assess some modelling techniques for FMD that are well supported by scientific evidence from the literature with a focus on their use in African countries where the disease remains enzootic. In particular, this study attempted to provide a synopsis of the relative strengths and weaknesses of these models and their relevance to FMD prevention policies. A literature search was conducted to identify quantitative and qualitative risk assessments for FMD, including studies that describe FMD risk factor modelling and spatiotemporal analysis. A description of retrieved papers and a critical assessment of the modelling methods, main findings and their limitations were performed. Different types of models have been used depending on the purpose of the study and the nature of available data. The most frequently identified factors associated with the risk of FMD occurrence were the movement (especially uncontrolled animal movement) and the mixing of animals around water and grazing points. Based on the qualitative and quantitative risk assessment studies, the critical pathway analysis showed that the overall risk of FMDV entering a given country is low. However, in some cases, this risk can be elevated, especially when illegal importation of meat and the movement of terrestrial livestock are involved. Depending on the approach used, these studies highlight shortcomings associated with the application of models and the lack of reliable data from endemic settings. Therefore, the development and application of specific models for use in FMD endemic countries including Africa is encouraged.
Collapse
Affiliation(s)
- Bachir Souley Kouato
- Research Unit in Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animals & Health (FARAH) Centre, Faculty of Veterinary Medicine, University of Liege, Liege, Belgium
- Institut National de la Recherche Agronomique du Niger (INRAN), Niamey, Niger
| | - Kris De Clercq
- Operational Directorate Viral Diseases, Unit Vesicular and Exotic Diseases, Veterinary and Agrochemical Research Centre (CODA-CERVA), Brussels, Belgium
| | - Emmanuel Abatih
- Department of Mathematics, Computer Sciences and Statistics, University of Gent, Krijgslaan Gent, Belgium
| | - Fabiana Dal Pozzo
- Research Unit in Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animals & Health (FARAH) Centre, Faculty of Veterinary Medicine, University of Liege, Liege, Belgium
| | - Donald P. King
- The Pirbright Institute, Ash Road, Pirbright, Surrey, United Kingdom
| | - Eric Thys
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Hamani Marichatou
- Université Abdou Moumouni de Niamey, Faculté d'Agronomie, Niamey, Niger
| | - Claude Saegerman
- Research Unit in Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animals & Health (FARAH) Centre, Faculty of Veterinary Medicine, University of Liege, Liege, Belgium
- * E-mail:
| |
Collapse
|
12
|
Meadows AJ, Mundt CC, Keeling MJ, Tildesley MJ. Disentangling the influence of livestock vs. farm density on livestock disease epidemics. Ecosphere 2018. [DOI: 10.1002/ecs2.2294] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Amanda J. Meadows
- Department of Botany and Plant Pathology; Oregon State University; Cordley Hall, 2701 SW Campus Way Corvallis Oregon 97331 USA
| | - Christopher C. Mundt
- Department of Botany and Plant Pathology; Oregon State University; Cordley Hall, 2701 SW Campus Way Corvallis Oregon 97331 USA
| | - Matt J. Keeling
- Department of Biological Sciences; University of Warwick; Gibbet Hill Road Coventry CV4 7AL UK
| | - Michael J. Tildesley
- Department of Biological Sciences; University of Warwick; Gibbet Hill Road Coventry CV4 7AL UK
| |
Collapse
|
13
|
Shanafelt DW, Jones G, Lima M, Perrings C, Chowell G. Forecasting the 2001 Foot-and-Mouth Disease Epidemic in the UK. ECOHEALTH 2018; 15:338-347. [PMID: 29238900 PMCID: PMC6132414 DOI: 10.1007/s10393-017-1293-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 05/24/2023]
Abstract
Near real-time epidemic forecasting approaches are needed to respond to the increasing number of infectious disease outbreaks. In this paper, we retrospectively assess the performance of simple phenomenological models that incorporate early sub-exponential growth dynamics to generate short-term forecasts of the 2001 foot-and-mouth disease epidemic in the UK. For this purpose, we employed the generalized-growth model (GGM) for pre-peak predictions and the generalized-Richards model (GRM) for post-peak predictions. The epidemic exhibits a growth-decelerating pattern as the relative growth rate declines inversely with time. The uncertainty of the parameter estimates [Formula: see text] narrows down and becomes more precise using an increasing amount of data of the epidemic growth phase. Indeed, using only the first 10-15 days of the epidemic, the scaling of growth parameter (p) displays wide uncertainty with the confidence interval for p ranging from values ~ 0.5 to 1.0, indicating that less than 15 epidemic days of data are not sufficient to discriminate between sub-exponential (i.e., p < 1) and exponential growth dynamics (i.e., p = 1). By contrast, using 20, 25, or 30 days of epidemic data, it is possible to recover estimates of p around 0.6 and the confidence interval is substantially below the exponential growth regime. Local and national bans on the movement of livestock and a nationwide cull of infected and contiguous premises likely contributed to the decelerating trajectory of the epidemic. The GGM and GRM provided useful 10-day forecasts of the epidemic before and after the peak of the epidemic, respectively. Short-term forecasts improved as the model was calibrated with an increasing length of the epidemic growth phase. Phenomenological models incorporating generalized-growth dynamics are useful tools to generate short-term forecasts of epidemic growth in near real time, particularly in the context of limited epidemiological data as well as information about transmission mechanisms and the effects of control interventions.
Collapse
Affiliation(s)
- David W Shanafelt
- Centre for Biodiversity, Theory and Modelling, Station d'Ecologie Théorique et Expérimentale du CNRS, Moulis, France
| | | | - Mauricio Lima
- Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile
| | - Charles Perrings
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Gerardo Chowell
- School of Public Health, Georgia State University, Atlanta, GA, USA.
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.
| |
Collapse
|
14
|
Van Andel M, Hollings T, Bradhurst R, Robinson A, Burgman M, Gates MC, Bingham P, Carpenter T. Does Size Matter to Models? Exploring the Effect of Herd Size on Outputs of a Herd-Level Disease Spread Simulator. Front Vet Sci 2018; 5:78. [PMID: 29780811 PMCID: PMC5946670 DOI: 10.3389/fvets.2018.00078] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/27/2018] [Indexed: 12/16/2022] Open
Abstract
Disease spread modeling is widely used by veterinary authorities to predict the impact of emergency animal disease outbreaks in livestock and to evaluate the cost-effectiveness of different management interventions. Such models require knowledge of basic disease epidemiology as well as information about the population of animals at risk. Essential demographic information includes the production system, animal numbers, and their spatial locations yet many countries with significant livestock industries do not have publically available and accurate animal population information at the farm level that can be used in these models. The impact of inaccuracies in data on model outputs and the decisions based on these outputs is seldom discussed. In this analysis, we used the Australian Animal Disease model to simulate the spread of foot-and-mouth disease seeded into high-risk herds in six different farming regions in New Zealand. We used three different susceptible animal population datasets: (1) a gold standard dataset comprising known herd sizes, (2) a dataset where herd size was simulated from a beta-pert distribution for each herd production type, and (3) a dataset where herd size was simplified to the median herd size for each herd production type. We analyzed the model outputs to compare (i) the extent of disease spread, (ii) the length of the outbreaks, and (iii) the possible impacts on decisions made for simulated outbreaks in different regions. Model outputs using the different datasets showed statistically significant differences, which could have serious implications for decision making by a competent authority. Outbreak duration, number of infected properties, and vaccine doses used during the outbreak were all significantly smaller for the gold standard dataset when compared with the median herd size dataset. Initial outbreak location and disease control strategy also significantly influenced the duration of the outbreak and number of infected premises. The study findings demonstrate the importance of having accurate national-level population datasets to ensure effective decisions are made before and during disease outbreaks, reducing the damage and cost.
Collapse
Affiliation(s)
- Mary Van Andel
- Investigation and Diagnostic Centre, Surveillance and Investigation Team (Animal Health), Operations Branch, Ministry for Primary Industries, Wallaceville, New Zealand
| | - Tracey Hollings
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Melbourne, VIC, Australia
| | - Richard Bradhurst
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Melbourne, VIC, Australia
| | - Andrew Robinson
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Melbourne, VIC, Australia
| | - Mark Burgman
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Melbourne, VIC, Australia.,Centre for Environmental Policy, Imperial College London, London, United Kingdom
| | - M Carolyn Gates
- Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Paul Bingham
- Investigation and Diagnostic Centre, Surveillance and Investigation Team (Animal Health), Operations Branch, Ministry for Primary Industries, Wallaceville, New Zealand
| | - Tim Carpenter
- Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| |
Collapse
|
15
|
Predicting farm-level animal populations using environmental and socioeconomic variables. Prev Vet Med 2017; 145:121-132. [DOI: 10.1016/j.prevetmed.2017.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 02/07/2023]
|
16
|
Walker R, Blackburn J. Biothreat Reduction and Economic Development: The Case of Animal Husbandry in Central Asia. Front Public Health 2015; 3:270. [PMID: 26779468 PMCID: PMC4688358 DOI: 10.3389/fpubh.2015.00270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 11/12/2015] [Indexed: 11/28/2022] Open
Abstract
Improving human welfare is a critical global concern, but not always easy to achieve. Complications in this regard have been faced by the states of the Former Soviet Union, where socialist-style economic institutions have disappeared, and the transition to a market economy has been slow in coming. Lack of capital, ethnic conflict, and political instability have at times undermined the institutional reform that would be necessary to enable economic efficiency and development. Nowhere are such challenges more pronounced than in the new nation states of central Asia, including Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Here, a severe climate limits agriculture, and industrialization has been inhibited by lack of infrastructure, low levels of human capital, and a scarcity of financial resources. These conditions are aggravated by the fact that the central Asian states are landlocked, far from centers of market demand and capital availability. Despite these daunting barriers, development potential does exist, and the goal of the paper is to consider central Asia's pastoral economy, with a focus on Kazakhstan, which stands poised to become a regional growth pole. The article pursues its goal as follows. It first addresses the biothreat situation to central Asian livestock herds, the most significant existing impediment to realizing the full market potential of the region's animal products. Next, it provides an outline of interventions that can reduce risk levels for key biothreats impacting central Asia, namely foot and mouth disease (FMD), which greatly impacts livestock and prohibits export, and Brucellosis, a bacterial zoonosis with high incidence in both humans and livestock in the region. Included is an important success story involving the FMD eradication programs in Brazil, which enabled an export boom in beef. After this comes a description of the epidemiological situation in Kazakhstan; here, the article considers the role of wildlife in acting as a possible disease reservoir, which presents a conservation issue for the Kazakhstani case. This is followed by a discussion of the role of science in threat reduction, particularly with respect to the potential offered by geospatial technologies to improve our epidemiological knowledge base. The article concludes with an assessment of the research that would be necessary to identify feasible pathways to develop the economic potential of central Asian livestock production as changes in policy are implemented and livestock health improves.
Collapse
Affiliation(s)
- Robert Walker
- Department of Geography, Center for Latin American Studies, University of Florida, Gainesville, FL, USA
| | - Jason Blackburn
- Department of Geography, Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| |
Collapse
|
17
|
Porphyre T, Auty HK, Tildesley MJ, Gunn GJ, Woolhouse MEJ. Vaccination against foot-and-mouth disease: do initial conditions affect its benefit? PLoS One 2013; 8:e77616. [PMID: 24204895 PMCID: PMC3815046 DOI: 10.1371/journal.pone.0077616] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/11/2013] [Indexed: 11/29/2022] Open
Abstract
When facing incursion of a major livestock infectious disease, the decision to implement a vaccination programme is made at the national level. To make this decision, governments must consider whether the benefits of vaccination are sufficient to outweigh potential additional costs, including further trade restrictions that may be imposed due to the implementation of vaccination. However, little consensus exists on the factors triggering its implementation on the field. This work explores the effect of several triggers in the implementation of a reactive vaccination-to-live policy when facing epidemics of foot-and-mouth disease. In particular, we tested whether changes in the location of the incursion and the delay of implementation would affect the epidemiological benefit of such a policy in the context of Scotland. To reach this goal, we used a spatial, premises-based model that has been extensively used to investigate the effectiveness of mitigation procedures in Great Britain. The results show that the decision to vaccinate, or not, is not straightforward and strongly depends on the underlying local structure of the population-at-risk. With regards to disease incursion preparedness, simply identifying areas of highest population density may not capture all complexities that may influence the spread of disease as well as the benefit of implementing vaccination. However, if a decision to vaccinate is made, we show that delaying its implementation in the field may markedly reduce its benefit. This work provides guidelines to support policy makers in their decision to implement, or not, a vaccination-to-live policy when facing epidemics of infectious livestock disease.
Collapse
Affiliation(s)
- Thibaud Porphyre
- Epidemiology Group, Centre for Immunity, Infection and Evolution, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
- * E-mail:
| | - Harriet K. Auty
- Epidemiology Research Unit, Scotland’s Rural College, Inverness, United Kingdom
| | - Michael J. Tildesley
- Centre for Complexity Science, Zeeman Building, University of Warwick, Coventry, United Kingdom
| | - George J. Gunn
- Epidemiology Research Unit, Scotland’s Rural College, Inverness, United Kingdom
| | - Mark E. J. Woolhouse
- Epidemiology Group, Centre for Immunity, Infection and Evolution, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
| |
Collapse
|
18
|
Boden LA, Parkin TDH, Yates J, Mellor D, Kao RR. An online survey of horse-owners in Great Britain. BMC Vet Res 2013; 9:188. [PMID: 24074003 PMCID: PMC3850011 DOI: 10.1186/1746-6148-9-188] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 09/26/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Contingency planning for potential equine infectious disease outbreaks relies on accurate information on horse location and movements to estimate the risk of dissemination of disease(s). An online questionnaire was used to obtain unique information linking owner and horse location to characteristics of horse movements within and outwith Great Britain (GB). RESULTS This online survey yielded a strong response, providing more than four times the target number of respondents (1000 target respondents) living in all parts of GB. Key demographic findings of this study indicated that horses which were kept on livery yards and riding schools were likely to be found in urban environments, some distance away from the owner's home and vaccinated against influenza and herpes virus. Survey respondents were likely to travel greater than 10 miles to attend activities such as eventing or endurance but were also likely to travel and return home within a single day (58.6%, 2063/3522). This may affect the geographical extent and speed of disease spread, if large numbers of people from disparate parts of the country are attending the same event and the disease agent is highly infectious or virulent. The greatest risk for disease introduction and spread may be represented by a small proportion of people who import or travel internationally with their horses. These respondents were likely to have foreign horse passports, which were not necessarily recorded in the National Equine Database (NED), making the location of these horses untraceable. CONCLUSIONS These results illustrate the difficulties which exist with national GB horse traceability despite the existence of the NED and the horse passport system. This study also demonstrates that an online approach could be adopted to obtain important demographic data on GB horse owners on a more routine and frequent basis to inform decisions or policy pertaining to equine disease control. This represents a reasonable alternative to collection of GB horse location and movement data given that the NED no longer exists and there is no immediate plan to replace it.
Collapse
Affiliation(s)
- Lisa A Boden
- Boyd Orr Centre for Population and Ecosystem Health, School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow G61 1QH, Scotland.
| | | | | | | | | |
Collapse
|
19
|
Allepuz A, Stevenson M, Kivaria F, Berkvens D, Casal J, Picado A. Risk Factors for Foot-and-Mouth Disease in Tanzania, 2001-2006. Transbound Emerg Dis 2013; 62:127-36. [DOI: 10.1111/tbed.12087] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Indexed: 11/30/2022]
Affiliation(s)
- A. Allepuz
- Centre de Recerca en Sanitat Animal (CReSA); UAB-IRTA; Campus de la Universitat Autònoma de Barcelona; Barcelona Spain
- Departament de Sanitat i Anatomia Animals; Universitat Autònoma de Barcelona; Barcelona Spain
| | - M. Stevenson
- EpiCentre; Institute of Veterinary, Animal, and Biomedical Sciences; Massey University; Palmerston North New Zealand
| | - F. Kivaria
- National Epidemiology Section; Ministry of Livestock and Fisheries Development; Dar es Salaam Tanzania
| | - D. Berkvens
- Animal Health Department; Institute of Tropical Medicine; Antwerpen Belgium
| | - J. Casal
- Centre de Recerca en Sanitat Animal (CReSA); UAB-IRTA; Campus de la Universitat Autònoma de Barcelona; Barcelona Spain
- Departament de Sanitat i Anatomia Animals; Universitat Autònoma de Barcelona; Barcelona Spain
| | - A. Picado
- School of Life Sciences; University of Warwick; Coventry UK
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona); Barcelona Spain
| |
Collapse
|
20
|
Tildesley MJ, Ryan SJ. Disease prevention versus data privacy: using landcover maps to inform spatial epidemic models. PLoS Comput Biol 2012; 8:e1002723. [PMID: 23133352 PMCID: PMC3486837 DOI: 10.1371/journal.pcbi.1002723] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 08/08/2012] [Indexed: 11/21/2022] Open
Abstract
The availability of epidemiological data in the early stages of an outbreak of an infectious disease is vital for modelers to make accurate predictions regarding the likely spread of disease and preferred intervention strategies. However, in some countries, the necessary demographic data are only available at an aggregate scale. We investigated the ability of models of livestock infectious diseases to predict epidemic spread and obtain optimal control policies in the event of imperfect, aggregated data. Taking a geographic information approach, we used land cover data to predict UK farm locations and investigated the influence of using these synthetic location data sets upon epidemiological predictions in the event of an outbreak of foot-and-mouth disease. When broadly classified land cover data were used to create synthetic farm locations, model predictions deviated significantly from those simulated on true data. However, when more resolved subclass land use data were used, moderate to highly accurate predictions of epidemic size, duration and optimal vaccination and ring culling strategies were obtained. This suggests that a geographic information approach may be useful where individual farm-level data are not available, to allow predictive analyses to be carried out regarding the likely spread of disease. This method can also be used for contingency planning in collaboration with policy makers to determine preferred control strategies in the event of a future outbreak of infectious disease in livestock. Mathematical models of infectious diseases are increasingly used to inform policy decisions. The advantages of such models are that multiple control options can be rapidly tested and compared, without the risks and costs associated with field experiments. However, for such models to be practically useful tools detailed data (both in terms of populations and epidemiology) are required. In many countries, such as the USA, individual-level demographic information on livestock farms is generally lacking. However, remotely sensed information (such as satellite images and land-use maps) provides the potential to generate these data or produce surrogate populations. In this paper we use land cover data to predict farm locations in the UK and investigate the effect of a precise knowledge of farm locations upon epidemiological predictions in the event of a foot-and-mouth disease epidemic. Our results show that, when highly resolved land cover data are used to predict farm locations, accurate predictions of epidemic sizes, durations and preferred intervention strategies can be obtained. This suggests that land cover data may be used in countries where individual farm-level data are not available, to allow for analyses to be carried out regarding the likely spread of disease in future outbreaks.
Collapse
Affiliation(s)
- Michael J Tildesley
- Centre for Complexity Science, Zeeman Building, University of Warwick, Coventry, United Kingdom.
| | | |
Collapse
|
21
|
Bessell PR, Rotariu O, Innocent GT, Smith-Palmer A, Strachan NJC, Forbes KJ, Cowden JM, Reid SWJ, Matthews L. Using sequence data to identify alternative routes and risk of infection: a case-study of campylobacter in Scotland. BMC Infect Dis 2012; 12:80. [PMID: 22462563 PMCID: PMC3340322 DOI: 10.1186/1471-2334-12-80] [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: 08/29/2011] [Accepted: 04/01/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic typing data are a potentially powerful resource for determining how infection is acquired. In this paper MLST typing was used to distinguish the routes and risks of infection of humans with Campylobacter jejuni from poultry and ruminant sources METHODS C. jejuni samples from animal and environmental sources and from reported human cases confirmed between June 2005 and September 2006 were typed using MLST. The STRUCTURE software was used to assign the specific sequence types of the sporadic human cases to a particular source. We then used mixed case-case logistic regression analysis to compare the risk factors for being infected with C. jejuni from different sources. RESULTS A total of 1,599 (46.3%) cases were assigned to poultry, 1,070 (31.0%) to ruminant and 67 (1.9%) to wild bird sources; the remaining 715 (20.7%) did not have a source that could be assigned with a probability of greater than 0.95. Compared to ruminant sources, cases attributed to poultry sources were typically among adults (odds ratio (OR) = 1.497, 95% confidence intervals (CIs) = 1.211, 1.852), not among males (OR = 0.834, 95% CIs = 0.712, 0.977), in areas with population density of greater than 500 people/km2 (OR = 1.213, 95% CIs = 1.030, 1.431), reported in the winter (OR = 1.272, 95% CIs = 1.067, 1.517) and had undertaken recent overseas travel (OR = 1.618, 95% CIs = 1.056, 2.481). The poultry assigned strains had a similar epidemiology to the unassigned strains, with the exception of a significantly higher likelihood of reporting overseas travel in unassigned strains. CONCLUSIONS Rather than estimate relative risks for acquiring infection, our analyses show that individuals acquire C. jejuni infection from different sources have different associated risk factors. By enhancing our ability to identify at-risk groups and the times at which these groups are likely to be at risk, this work allows public health messages to be targeted more effectively. The rapidly increasing capacity to conduct genetic typing of pathogens makes such traced epidemiological analysis more accessible and has the potential to substantially enhance epidemiological risk factor studies.
Collapse
Affiliation(s)
- Paul R Bessell
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Rd, Glasgow, UK.
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Tildesley MJ, Smith G, Keeling MJ. Modeling the spread and control of foot-and-mouth disease in Pennsylvania following its discovery and options for control. Prev Vet Med 2011; 104:224-39. [PMID: 22169708 DOI: 10.1016/j.prevetmed.2011.11.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 11/11/2011] [Accepted: 11/12/2011] [Indexed: 01/13/2023]
Abstract
In this paper, we simulate outbreaks of foot-and-mouth disease in the Commonwealth of Pennsylvania, USA - after the introduction of a state-wide movement ban - as they might unfold in the presence of mitigation strategies. We have adapted a model previously used to investigate FMD control policies in the UK to examine the potential for disease spread given an infection seeded in each county in Pennsylvania. The results are highly dependent upon the county of introduction and the spatial scale of transmission. Should the transmission kernel be identical to that for the UK, the epidemic impact is limited to fewer than 20 premises, regardless of the county of introduction. However, for wider kernels where infection can spread further, outbreaks seeded in or near the county with highest density of premises and animals result in large epidemics (>150 premises). Ring culling and vaccination reduce epidemic size, with the optimal radius of the rings being dependent upon the county of introduction. Should the kernel width exceed a given county-dependent threshold, ring culling is unable to control the epidemic. We find that a vaccinate-to-live policy is generally preferred to ring culling (in terms of reducing the overall number of premises culled), indicating that well-targeted control can dramatically reduce the risk of large scale outbreaks of foot-and-mouth disease occurring in Pennsylvania.
Collapse
Affiliation(s)
- Michael J Tildesley
- Centre for Complexity Science, Zeeman Building, University of Warwick, Coventry, CV4 7AL, UK.
| | | | | |
Collapse
|
23
|
Woolhouse M. How to make predictions about future infectious disease risks. Philos Trans R Soc Lond B Biol Sci 2011; 366:2045-54. [PMID: 21624924 PMCID: PMC3130384 DOI: 10.1098/rstb.2010.0387] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Formal, quantitative approaches are now widely used to make predictions about the likelihood of an infectious disease outbreak, how the disease will spread, and how to control it. Several well-established methodologies are available, including risk factor analysis, risk modelling and dynamic modelling. Even so, predictive modelling is very much the ‘art of the possible’, which tends to drive research effort towards some areas and away from others which may be at least as important. Building on the undoubted success of quantitative modelling of the epidemiology and control of human and animal diseases such as AIDS, influenza, foot-and-mouth disease and BSE, attention needs to be paid to developing a more holistic framework that captures the role of the underlying drivers of disease risks, from demography and behaviour to land use and climate change. At the same time, there is still considerable room for improvement in how quantitative analyses and their outputs are communicated to policy makers and other stakeholders. A starting point would be generally accepted guidelines for ‘good practice’ for the development and the use of predictive models.
Collapse
Affiliation(s)
- Mark Woolhouse
- Centre for Infectious Diseases, University of Edinburgh, Ashworth Laboratories, Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK.
| |
Collapse
|
24
|
Volkova VV, Bessell PR, Woolhouse MEJ, Savill NJ. Evaluation of risks of foot-and-mouth disease in Scotland to assist with decision making during the 2007 outbreak in the UK. Vet Rec 2011; 169:124. [PMID: 21730033 PMCID: PMC3361954 DOI: 10.1136/vr.d2715] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
An outbreak of foot-and-mouth disease (FMD) occurred in Surrey on August 3, 2007. A Great Britain-wide ban on livestock movements was implemented immediately. This coincided with the start of seasonal sheep movements off the hills in Scotland; the majority of these animals are sold via markets. The ban therefore posed severe economic and animal-welfare hardships if it was to last through September and beyond. The Scottish Government commissioned an analysis to assess the risk of re-opening markets given the uncertainty about whether FMD had entered Scotland. Tracing of livestock moved from within the risk zone in England between July 16 and August 3 identified contact chains to 12 Scottish premises; veterinary field inspections found a further three unrecorded movements. No signs of infection were found on these holdings. Under the conservative assumption that a single unknown Scottish holding was infected with FMD, an estimate of the time-dependent probability of Scotland being FMD free given no detection was made. Analyses indicated that if FMD was not detected by early to mid-September then it was highly probable that Scotland was FMD free. Risk maps were produced to visualise the potential spread of FMD across Scotland if it was to spread either locally or via market sales.
Collapse
Affiliation(s)
- V V Volkova
- School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, King's Buildings, West Mains Road, Edinburgh EH9 3JT.
| | | | | | | |
Collapse
|
25
|
Using the systematic review methodology to evaluate factors that influence the persistence of influenza virus in environmental matrices. Appl Environ Microbiol 2010; 77:1049-60. [PMID: 21148699 DOI: 10.1128/aem.02733-09] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Understanding factors that influence persistence of influenza virus in an environment without host animals is critical to appropriate decision-making for issues such as quarantine downtimes, setback distances, and eradication programs in livestock production systems. This systematic review identifies literature describing persistence of influenza virus in environmental samples, i.e., air, water, soil, feces, and fomites. An electronic search of PubMed, CAB, AGRICOLA, Biosis, and Compendex was performed, and citation relevance was determined according to the aim of the review. Quality assessment of relevant studies was performed using criteria from experts in virology, disease ecology, and environmental science. A total of 9,760 abstracts were evaluated, and 40 appeared to report the persistence of influenza virus in environmental samples. Evaluation of full texts revealed that 19 of the 40 studies were suitable for review, as they described virus concentration measured at multiple sampling times, with viruses detectable at least twice. Seven studies reported persistence in air (six published before 1970), seven in water (five published after 1990), two in feces, and three on surfaces. All three fomite and five air studies addressed human influenza virus, and all water and feces studies pertained to avian influenza virus. Outcome measurements were transformed to half-lives, and resultant multivariate mixed linear regression models identified influenza virus surviving longer in water than in air. Temperature was a significant predictor of persistence over all matrices. Salinity and pH were significant predictors of persistence in water conditions. An assessment of the methodological quality review of the included studies revealed significant gaps in reporting critical aspects of study design.
Collapse
|
26
|
Suh M, Lee J, Chi HJ, Kim YK, Kang DY, Hur NW, Ha KH, Lee DH, Kim CS. [Mathematical modeling of the novel influenza A (H1N1) virus and evaluation of the epidemic response strategies in the Republic of Korea]. J Prev Med Public Health 2010; 43:109-16. [PMID: 20383043 DOI: 10.3961/jpmph.2010.43.2.109] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES The pandemic of novel influenza A (H1N1) virus has required decision-makers to act in the face of the substantial uncertainties. In this study, we evaluated the potential impact of the pandemic response strategies in the Republic of Korea using a mathematical model. METHODS We developed a deterministic model of a pandemic (H1N1) 2009 in a structured population using the demographic data from the Korean population and the epidemiological feature of the pandemic (H1N1) 2009. To estimate the parameter values for the deterministic model, we used the available data from the previous studies on pandemic influenza. The pandemic response strategies of the Republic of Korea for novel influenza A (H1N1) virus such as school closure, mass vaccination (70% of population in 30 days), and a policy for anti-viral drug (treatment or prophylaxis) were applied to the deterministic model. RESULTS The effect of two-week school closure on the attack rate was low regardless of the timing of the intervention. The earlier vaccination showed the effect of greater delays in reaching the peak of outbreaks. When it was no vaccination, vaccination at initiation of outbreak, vaccination 90 days after the initiation of outbreak and vaccination at the epidemic peak point, the total number of clinical cases for 400 days were 20.8 million, 4.4 million, 4.7 million and 12.6 million, respectively. The pandemic response strategies of the Republic of Korea delayed the peak of outbreaks (about 40 days) and decreased the number of cumulative clinical cases (8 million). CONCLUSIONS Rapid vaccination was the most important factor to control the spread of pandemic influenza, and the response strategies of the Republic of Korea were shown to delay the spread of pandemic influenza in this deterministic model.
Collapse
Affiliation(s)
- Mina Suh
- Department of Preventive Medicine, Yonsei University College of Medicine, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Tildesley MJ, Bessell PR, Keeling MJ, Woolhouse MEJ. The role of pre-emptive culling in the control of foot-and-mouth disease. Proc Biol Sci 2009; 276:3239-48. [PMID: 19570791 PMCID: PMC2817163 DOI: 10.1098/rspb.2009.0427] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 06/02/2009] [Indexed: 11/12/2022] Open
Abstract
The 2001 foot-and-mouth disease epidemic was controlled by culling of infectious premises and pre-emptive culling intended to limit the spread of disease. Of the control strategies adopted, routine culling of farms that were contiguous to infected premises caused the most controversy. Here we perform a retrospective analysis of the culling of contiguous premises as performed in 2001 and a simulation study of the effects of this policy on reducing the number of farms affected by disease. Our simulation results support previous studies and show that a national policy of contiguous premises (CPs) culling leads to fewer farms losing livestock. The optimal national policy for controlling the 2001 epidemic is found to be the targeting of all contiguous premises, whereas for localized outbreaks in high animal density regions, more extensive fixed radius ring culling is optimal. Analysis of the 2001 data suggests that the lowest-risk CPs were generally prioritized for culling, however, even in this case, the policy is predicted to be effective. A sensitivity analysis and the development of a spatially heterogeneous policy show that the optimal culling level depends upon the basic reproductive ratio of the infection and the width of the dispersal kernel. These analyses highlight an important and probably quite general result: optimal control is highly dependent upon the distance over which the pathogen can be transmitted, the transmission rate of infection and local demography where the disease is introduced.
Collapse
Affiliation(s)
- Michael J Tildesley
- Centre for Infectious Diseases, University of Edinburgh, Ashworth Laboratories, Kings Buildings, Edinburgh EH9 3JT, UK.
| | | | | | | |
Collapse
|