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Wongnak P, Yano T, Sekiguchi S, Chalvet-Monfray K, Premashthira S, Thanapongtharm W, Wiratsudakul A. A stochastic modeling study of quarantine strategies against foot-and-mouth disease risks through cattle trades across the Thailand-Myanmar border. Prev Vet Med 2024; 230:106282. [PMID: 39033658 DOI: 10.1016/j.prevetmed.2024.106282] [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: 04/08/2023] [Revised: 05/30/2024] [Accepted: 07/03/2024] [Indexed: 07/23/2024]
Abstract
Foot-and-mouth disease (FMD) is an important endemic disease in livestock in Southeast Asia. Transboundary movement of animals may result in the transnational disease spread. A major cattle market is located at the Thailand-Myanmar border, where most cattle imported from Myanmar are traded. In this study, we built a stochastic susceptible-exposed-infectious-recovered (SEIR) model to investigate the effectiveness of a private animal quarantine service center in preventing FMDV from entering the major cattle market. We computed with different parameters and found that, with 50 % vaccine effectiveness, the risk of releasing infected cattle to the market per batch was generally low during the quarantine period of 21 and 28 days, with the risk ranging from 0.071 to 0.078 and 0.032 to 0.036, respectively. Despite the best scenario, the zero-risk state is difficult to attain. The sensitivity analysis highlights that the percentage of immune animals before entering the quarantine centers and the vaccine effectiveness are important factors. In conclusion, the 21-day quarantine period mitigates the risk of FMDV introduction into the cattle market. This control measure should be rigorously maintained to sustainably prevent FMDV outbreaks through transboundary animal movements, especially among countries in FMD-endemic regions.
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Affiliation(s)
- Phrutsamon Wongnak
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Université de Lyon, INRAE, VetAgro Sup, UMR EPIA, Marcy l'Etoile, France; Université Clermont Auvergne, INRAE, VetAgro Sup, UMR EPIA, Saint-Genès-Champanelle, France
| | - Terdsak Yano
- Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Satoshi Sekiguchi
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan; Center for Animal Disease Control, University of Miyazaki, Miyazaki, Japan
| | - Karine Chalvet-Monfray
- Université de Lyon, INRAE, VetAgro Sup, UMR EPIA, Marcy l'Etoile, France; Université Clermont Auvergne, INRAE, VetAgro Sup, UMR EPIA, Saint-Genès-Champanelle, France
| | | | | | - Anuwat Wiratsudakul
- Department of Clinical Sciences and Public Health, and the Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic Animals, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand.
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2
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Hobbelen P, Hagenaars T, Peri Markovich M, Bellaiche M, Giovannini A, De Massis F, de Koeijer A. The optimisation of Salmonella surveillance programmes for pullet and layer farms using local farm density as a risk factor. PLoS One 2024; 19:e0291896. [PMID: 38630759 PMCID: PMC11023578 DOI: 10.1371/journal.pone.0291896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 03/23/2024] [Indexed: 04/19/2024] Open
Abstract
Human salmonellosis cases are often caused by Salmonella serovars Enteritidis and Typhimurium and associated with the consumption of eggs and egg products. Many countries therefore implemented general surveillance programmes on pullet and layer farms. The identification of risk factors for Salmonella infection may be used to improve the performance of these surveillance programmes. The aims of this study were therefore to determine 1) whether local farm density is a risk factor for the infection of pullet and layer farms by Salmonella Enteritidis and Typhimurium and 2) whether the sampling effort of surveillance programmes can be reduced by accounting for this risk factor, while still providing sufficient control of these serovars. We assessed the importance of local farm density as a risk factor by fitting transmission kernels to Israeli surveillance data during the period from June 2017 to April 2019. The analysis shows that the risk of infection by serovars Enteritidis and Typhimurium significantly increased if infected farms were present within a radius of approximately 4 km and 0.3 km, respectively. We subsequently optimized a surveillance programme that subdivided layer farms into low and high risk groups based on the local farm density with and allowed the sampling frequency to vary between these groups. In this design, the pullet farms were always sampled one week prior to pullet distribution. Our analysis shows that the risk-based surveillance programme is able to keep the between-farm R0 of serovars Enteritidis and Typhimurium below 1 for all pullet and layer farms, while reducing the sampling effort by 32% compared to the currently implemented surveillance programme in Israel. The results of our study therefore indicate that local farm density is an important risk factor for infection of pullet and layer farms by Salmonella Enteritidis and Typhimurium and can be used to improve the performance of surveillance programmes.
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Affiliation(s)
- Peter Hobbelen
- Wageningen Bioveterinary Research, Lelystad, The Netherlands
| | | | | | | | - Armando Giovannini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, Teramo, Italy
| | - Fabrizio De Massis
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, Teramo, Italy
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3
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Chanchaidechachai T, Saatkamp HW, Hogeveen H, de Jong MCM, Fischer EAJ. Evaluation of foot and mouth disease control measures: Simulating two endemic areas of Thailand. Prev Vet Med 2023; 220:106045. [PMID: 37866130 DOI: 10.1016/j.prevetmed.2023.106045] [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: 03/17/2023] [Revised: 09/25/2023] [Accepted: 10/08/2023] [Indexed: 10/24/2023]
Abstract
Foot and mouth disease (FMD) is an important livestock disease in Thailand, with outbreaks occurring every year. However, the effects of FMD control measures in Thailand have received little research attention. Epidemiological models have been widely used to evaluate FMD outbreak control, but such a model has never been developed for Thailand. We constructed a stochastic between-farm transmission model to evaluate FMD control measures. The epidemiological unit of the model was the farm, which could be in different states: susceptible, latent, undetected infectious, detected infectious and recovered. The between-farm transmission was calculated by the sum of distance-dependent transmission and trade network transmission using parameters derived from FMD outbreaks in 2016-2017. We used this model to simulate the outbreaks with and without the implementation of the following control measures: culling all animals on infected farms, ring vaccination, animal movement restrictions and isolation of infected farms. The control measures were evaluated by estimating the number of secondarily infected farms and the outbreak duration for each scenario. The model was simulated in two study areas located in the Lamphaya Klang subdistrict (high farm density) and the Bo Phloi district (low farm density). The effects of control measures differed between the two study areas. When farm density was high, rigid control measures were required to prevent a major outbreak. Among all options, culling the animals on infected farms resulted in the lowest number of infected farms and the shortest outbreak duration. In contrast, for an area with a low farm density, less stringent control measures were sufficient to control the usually minor outbreaks. The results indicate that different areas require a different approach to control an outbreak of FMD.
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Affiliation(s)
- Thanicha Chanchaidechachai
- Business Economics Group, Wageningen University, Wageningen, the Netherlands; Research Unit of Data Innovation for Livestock, Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
| | - Helmut W Saatkamp
- Business Economics Group, Wageningen University, Wageningen, the Netherlands
| | - Henk Hogeveen
- Business Economics Group, Wageningen University, Wageningen, the Netherlands
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology Group, Wageningen University, Wageningen, the Netherlands
| | - Egil A J Fischer
- Department of Population Health Sciences, Division Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
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4
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Sanson RL, Rawdon TG, van Andel M, Yu Z. Modelling the field personnel resources to control foot-and-mouth disease outbreaks in New Zealand. Transbound Emerg Dis 2022; 69:3926-3939. [PMID: 36397293 DOI: 10.1111/tbed.14764] [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: 08/23/2022] [Accepted: 11/11/2022] [Indexed: 11/21/2022]
Abstract
The objective of the study was to simulate New Zealand's foot-and-mouth disease (FMD) operational plan to determine personnel requirements for an FMD response and understand how the numbers of front-line staff available could affect the size and duration of FMD outbreaks, when using stamping-out (SO) measures with or without vaccination. The model utilized a national dataset of all known livestock farms. Each simulation randomly seeded infection into a single farm. Transmission mechanisms included direct and indirect contacts, local and airborne spread. Prior to each simulation, the numbers of personnel available for front-line tasks (including contact tracing, surveillance of at-risk farms, depopulation and vaccination) were set randomly. In a random subset of simulations, vaccination was allowed to be deployed as an adjunct to SO. The effects of personnel numbers on the size and duration of epidemics were explored using machine learning methods. In the second stage of the study, using a subset of iterations where numbers of personnel were unconstrained, the number of personnel used each day were quantified. When personnel resources were unconstrained, the 95th percentile and maximum number of infected places (IPs) were 78 and 462, respectively, and the 95th percentile and maximum duration were 69 and 217 days, respectively. However, severe constraints on personnel resources allowed some outbreaks to exceed the size of the UK 2001 FMD epidemic which had 2026 IPs. The number of veterinarians available had a major influence on the size and duration of outbreaks, whereas the availability of other personnel types did not. A shortage of veterinarians was associated with an increase in time to detect and depopulate IPs, allowing for continued transmission. Emergency vaccination placed a short-term demand for additional staff at the start of the vaccination programme, but the overall number of person days used was similar to SO-only strategies. This study determined the optimal numbers of front-line personnel required to implement the current operational plans to support an FMD response in New Zealand. A shortage of veterinarians was identified as the most influential factor to impact disease control outcomes. Emergency vaccination led to earlier control of FMD outbreaks but at the cost of a short-term spike in demand for personnel. In conclusion, a successful response needs to have access to sufficient personnel, particularly veterinarians, trained in response roles and available at short notice.
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Affiliation(s)
| | - Thomas G Rawdon
- Diagnostics and Surveillance Services Directorate, Ministry for Primary Industries, Upper Hutt, New Zealand
| | - Mary van Andel
- Chief Veterinary Officer, Ministry for Primary Industries, Wellington, New Zealand
| | - Zhidong Yu
- Food Science and Risk Assessment, Ministry for Primary Industries, Wellington, New Zealand
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5
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Cabezas AH, Mapitse NJ, Tizzani P, Sanchez-Vazquez MJ, Stone M, Park MK. Analysis of suspensions and recoveries of official foot and mouth disease free status of WOAH Members between 1996 and 2020. Front Vet Sci 2022; 9:1013768. [PMID: 36387388 PMCID: PMC9650142 DOI: 10.3389/fvets.2022.1013768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 10/14/2022] [Indexed: 12/26/2022] Open
Abstract
Foot and mouth disease was the first disease for which, in 1996, the World Organisation for Animal Health (WOAH; founded as OIE) established an official list of disease-free territories, which has helped to facilitate the trade of animals and animal products from those territories. Since that year, there have been a number of suspensions of FMD-free status which have impacted the livestock industry of the territories affected. The objective of this study is to identify factors associated with the time taken to recover FMD-free status after suspension. Historical applications submitted (between 1996 and the first semester of 2020) by WOAH Members for recognition and recovery of FMD-free status were used as the main source of data. Only FMD-free status suspensions caused by outbreaks were considered. Data on the Member's socio-economic characteristics, livestock production systems, FMD outbreak characteristics, and control strategies were targeted for the analysis. The period of time taken to recover FMD-free status was estimated using Kaplan-Meier survival curves. A Cox proportional hazard model was used to identify factors associated with the time taken to recover FMD-free status after suspension. A total of 163 territories were granted official FMD-free status during the study period. The study sample consisted of 45 FMD-free status suspensions. Africa and the Americas accounted for over 50% of FMD-free status suspensions, while over 70% of these occurred in formerly FMD-free territories where vaccination was not practiced. The study noted that implementing a stamping-out or vaccination and remove policy shortened the time to recover FMD-free status, compared with a vaccination and retain policy. Other variables associated with the outcome were the income level of the Member, Veterinary Service capacity, time taken to implement control measures, time taken until the disposal of the last FMD case, whether the territory bordered FMD-infected territories, and time elapsed since FMD freedom. This analysis will contribute toward the understanding of the main determinants affecting the time to recover the FMD free status of WOAH Members and policy processes for FMD control and elimination.
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Affiliation(s)
- Aurelio H. Cabezas
- Status Department, World Organization for Animal Health, Paris, France,*Correspondence: Aurelio H. Cabezas
| | - Neo J. Mapitse
- Status Department, World Organization for Animal Health, Paris, France
| | - Paolo Tizzani
- World Animal Health Information and Analysis Department, World Organization for Animal Health, Paris, France
| | - Manuel J. Sanchez-Vazquez
- Pan American Center for Foot-and-Mouth Disease and Veterinary Public Health, Communicable Diseases and Environmental Determinants of Health, Pan American Health Organization/World Health Organization, Duque de Caxias, Rio de Janeiro, Brazil
| | - Matthew Stone
- International Standards and Science, World Organization for Animal Health, Paris, France
| | - Min-Kyung Park
- Status Department, World Organization for Animal Health, Paris, France,Min-Kyung Park
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6
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Chaulagain B, Contina JB, Mills K, Seibel RL, Mundt CC. Comparing the efficacy of control strategies for infectious disease outbreaks using field and simulation studies. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2631. [PMID: 35403765 DOI: 10.1002/eap.2631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 02/03/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Diseases characterized by long distance inoculum dispersal (LDD) are among the fastest spreading epidemics in both natural and managed landscapes. Management of such epidemics is extremely challenging because of asymptomatic infection extending at large spatial scales and frequent escape from the newly established disease sources. We compared the efficacy of area- and timing-based disease management strategies in artificially initiated field epidemics of wheat stripe rust and complemented with simulations from an updated version of the spatially explicit model EPIMUL, using model parameters relevant to field epidemics. The model was further used to expand the number of epidemic mitigations beyond that feasible to incorporate in the field. The field experiment was conducted for 2 years in two locations having different climatic conditions. Culling and protection treatments were applied at different times after epidemic initiation and to different spatial extents surrounding the outbreaks. In each experiment, treatments were replicated four times in plots 33.5 m long and 1.52 m wide with a 0.76 × 0.76 m inoculated focus centered within each plot. Disease gradients were assessed along the center lines of the plots at 1.52 m intervals both upwind and downwind from the focus. Both field and simulation results indicated that control measures applied over the entire population were highly effective in suppressing the epidemics by more than 99% but may not always be logistically and economically feasible at large spatial scales. Comparison between the variable sized treatment areas and application timings suggested that implementing contiguous premises (CP) cull at 1 day after first sporulation in the outbreak focus reduced rust by 52% and 60% in Corvallis and Madras, respectively. However, altering the cull size did not significantly affect the disease epidemic development, which suggested that early timing had a greater influence in suppressing the epidemics than did increased area of application. However, sufficiently large, treated areas may compensate for a delay in application timing to some extent. Results from these replicated treatments may help to devise appropriate management strategies for other LDD pathogens.
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Affiliation(s)
- Bhim Chaulagain
- College of Agricultural Sciences, Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Jean Bertrand Contina
- College of Agricultural Sciences, Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Karasi Mills
- College of Agricultural Sciences, Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Rachel L Seibel
- College of Agricultural Sciences, Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Christopher C Mundt
- College of Agricultural Sciences, Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
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7
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Emergency FMD Serotype O Vaccines Protect Cattle against Heterologous Challenge with a Variant Foot-and-Mouth Disease Virus from the O/ME-SA/Ind2001 Lineage. Vaccines (Basel) 2021; 9:vaccines9101110. [PMID: 34696216 PMCID: PMC8537456 DOI: 10.3390/vaccines9101110] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 09/21/2021] [Accepted: 09/21/2021] [Indexed: 11/17/2022] Open
Abstract
Vaccination is one of the best approaches to control and eradicate foot-and-mouth disease (FMD). To achieve this goal, vaccines with inactivated FMD virus antigen in suitable adjuvants are being used in addition to other control measures. However, only a limited number of vaccine strains are commercially available, which often have a restricted spectrum of activity against the different FMD virus strains in circulation. As a result, when new strains emerge, it is important to measure the efficacy of the current vaccine strains against these new variants. This is important for countries where FMD is endemic but also for countries that hold an FMD vaccine bank, to ensure they are prepared for emergency vaccination. The emergence and spread of the O/ME-SA/Ind-2001 lineage of viruses posed a serious threat to countries with OIE-endorsed FMD control plans who had not reported FMD for many years. In vitro vaccine-matching results showed a poor match (r1-value < 0.3) with the more widely used vaccine strain O1 Manisa and less protection in a challenge test. This paper describes the use of the O3039 vaccine strain as an alternative, either alone or in combination with the O1 Manisa vaccine strain with virulent challenge by a O/ME-SA/Ind-2001d sub-lineage virus from Algeria (O/ALG/3/2014). The experiment included challenge at 7 days post-vaccination (to study protection and emergency use) and 21 days post-vaccination (as in standard potency studies). The results indicated that the O3039 vaccine strain alone, as well as the combination with O1 Manisa, is effective against this strain of the O/ME-SA/Ind/2001d lineage, offering protection from clinical disease even after 7 days post-vaccination with a reduction in viraemia and virus excretion.
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8
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Capon TR, Garner MG, Tapsuwan S, Roche S, Breed AC, Liu S, Miller C, Bradhurst R, Hamilton S. A Simulation Study of the Use of Vaccination to Control Foot-and-Mouth Disease Outbreaks Across Australia. Front Vet Sci 2021; 8:648003. [PMID: 34458348 PMCID: PMC8385296 DOI: 10.3389/fvets.2021.648003] [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: 12/31/2020] [Accepted: 07/07/2021] [Indexed: 11/15/2022] Open
Abstract
This study examines the potential for foot-and-mouth disease (FMD) control strategies that incorporate vaccination to manage FMD spread for a range of incursion scenarios across Australia. Stakeholder consultation was used to formulate control strategies and incursion scenarios to ensure relevance to the diverse range of Australian livestock production regions and management systems. The Australian Animal Disease Spread model (AADIS) was used to compare nine control strategies for 13 incursion scenarios, including seven control strategies incorporating vaccination. The control strategies with vaccination differed in terms of their approaches for targeting areas and species. These strategies are compared with two benchmark strategies based on stamping out only. Outbreak size and duration were compared in terms of the total number of infected premises, the duration of the control stage of an FMD outbreak, and the number of vaccinated animals. The three key findings from this analysis are as follows: (1) smaller outbreaks can be effectively managed by stamping out without vaccination, (2) the size and duration of larger outbreaks can be significantly reduced when vaccination is used, and (3) different vaccination strategies produced similar reductions in the size and duration of an outbreak, but the number of animals vaccinated varied. Under current international standards for regaining FMD-free status, vaccinated animals need to be removed from the population at the end of the outbreak to minimize trade impacts. We have shown that selective, targeted vaccination strategies could achieve effective FMD control while significantly reducing the number of animals vaccinated.
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Affiliation(s)
| | | | | | - Sharon Roche
- Epidemiology and One Health Section, Department of Agriculture, Water and the Environment, Canberra, ACT, Australia
| | - Andrew C Breed
- Epidemiology and One Health Section, Department of Agriculture, Water and the Environment, Canberra, ACT, Australia.,School of Veterinary Science, University of Queensland, Brisbane, QLD, Australia
| | - Shuang Liu
- CSIRO Land & Water, Acton, ACT, Australia
| | - Corissa Miller
- Epidemiology and One Health Section, Department of Agriculture, Water and the Environment, Canberra, ACT, Australia
| | - Richard Bradhurst
- Centre of Excellence for Biosecurity Risk Analysis, The University of Melbourne, Melbourne, VIC, Australia
| | - Sam Hamilton
- Epidemiology and One Health Section, Department of Agriculture, Water and the Environment, Canberra, ACT, Australia
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9
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Chanchaidechachai T, de Jong MCM, Fischer EAJ. Spatial model of foot-and-mouth disease outbreak in an endemic area of Thailand. Prev Vet Med 2021; 195:105468. [PMID: 34428641 DOI: 10.1016/j.prevetmed.2021.105468] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 06/29/2021] [Accepted: 08/17/2021] [Indexed: 11/17/2022]
Abstract
Foot-and-mouth disease (FDM) is a disease of cloven-hoofed animals with high costs in animal welfare and animal production. Up to now, transmission between farms in FMD-endemic areas has been given little attention. Between farm transmission can be quantified by distance independent transmission parameters and a spatial transmission kernel indicating the rate of transmission of an infected farm to susceptible farms depending on the distance. The spatial transmission kernel and distance-independent transmission parameters were estimated from data of an FMD outbreak in Lamphaya Klang subdistrict in Thailand between 2016 and 2017. The spatial between-farm transmission rate in Lamphaya Klang subdistrict was higher compared with the spatial between-farm transmission rate from FMDV in epidemic areas. The result can be explained by the larger size of the within-farm outbreak in the endemic area due to no culling. The inclusion of distance-independent transmission parameters improved the model fit, which suggests the presence of transmission sources from outside the area and spread within the area independent of the distance between farms. The remaining distance-dependent transmission was mainly local and could be due to over-the-fence transmission or other forms of contact between nearby farms. Farm size on the kernel positively affects the transmission rate, by increasing both infectivity and susceptibility with increasing farm size. The results showed that both distance-dependent transmission and distance-independent transmission were contributed to FMDV transmission in Lamphaya Klang outbreak. These transmission parameters help to gain knowledge about FMD transmission dynamic in the endemic area.
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Affiliation(s)
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology Group, Wageningen University & Research, Wageningen, the Netherlands
| | - Egil A J Fischer
- Department of Population Health Sciences, Division Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
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10
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Bradhurst R, Garner G, Hóvári M, de la Puente M, Mintiens K, Yadav S, Federici T, Kopacka I, Stockreiter S, Kuzmanova I, Paunov S, Cacinovic V, Rubin M, Szilágyi J, Kókány ZS, Santi A, Sordilli M, Sighinas L, Spiridon M, Potocnik M, Sumption K. Development of a transboundary model of livestock disease in Europe. Transbound Emerg Dis 2021; 69:1963-1982. [PMID: 34169659 PMCID: PMC9545780 DOI: 10.1111/tbed.14201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 06/01/2021] [Indexed: 12/03/2022]
Abstract
Epidemiological models of notifiable livestock disease are typically framed at a national level and targeted for specific diseases. There are inherent difficulties in extending models beyond national borders as details of the livestock population, production systems and marketing systems of neighbouring countries are not always readily available. It can also be a challenge to capture heterogeneities in production systems, control policies, and response resourcing across multiple countries, in a single transboundary model. In this paper, we describe EuFMDiS, a continental‐scale modelling framework for transboundary animal disease, specifically designed to support emergency animal disease planning in Europe. EuFMDiS simulates the spread of livestock disease within and between countries and allows control policies to be enacted and resourced on a per‐country basis. It provides a sophisticated decision support tool that can be used to look at the risk of disease introduction, establishment and spread; control approaches in terms of effectiveness and costs; resource management; and post‐outbreak management issues.
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Affiliation(s)
- Richard Bradhurst
- Centre of Excellence for Biosecurity Risk Analysis, School of BioSciences, University of Melbourne, Melbourne, Australia
| | - Graeme Garner
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
| | - Márk Hóvári
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
| | - Maria de la Puente
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
| | - Koen Mintiens
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
| | - Shankar Yadav
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
| | - Tiziano Federici
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
| | - Ian Kopacka
- Division for Data, Statistics and Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Graz, Austria
| | - Simon Stockreiter
- Division for Data, Statistics and Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Graz, Austria
| | | | | | - Vladimir Cacinovic
- Veterinary Inspection and Control of Food Safety Sector, State Inspectorate, Zagreb, Croatia
| | - Martina Rubin
- Veterinary and Food Safety Directorate, Ministry of Agriculture, Zagreb, Croatia
| | | | | | - Annalisa Santi
- Veterinary Epidemiology Unit, Istituto Zooprofilattico della Lombardia e dell'Emilia-Romagna
| | - Marco Sordilli
- Istituto Zooprofilattico Sperimentale del Lazio e della Toscana, Rome, Italy
| | - Laura Sighinas
- National Sanitary Veterinary and Food Safety Authority, Bucharest, Romania
| | - Mihaela Spiridon
- National Sanitary Veterinary and Food Safety Authority, Bucharest, Romania
| | - Marko Potocnik
- Animal Health and Animal Welfare Division Administration of the Republic of Slovenia for Food Safety, Veterinary Sector and Plant Protection, Ljubljana, Slovenia
| | - Keith Sumption
- European Commission for the Control of Foot-and-Mouth Disease, FAO, Rome, Italy
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11
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Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Canali E, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortázar Schmidt C, Herskin M, Michel V, Miranda Chueca MÁ, Padalino B, Pasquali P, Sihvonen LH, Spoolder H, Ståhl K, Velarde A, Viltrop A, Winckler C, De Clercq K, Gubbins S, Klement E, Stegeman JA, Antoniou S, Aznar I, Broglia A, Papanikolaou A, Van der Stede Y, Zancanaro G, Roberts HC. Scientific Opinion on the assessment of the control measures for category A diseases of Animal Health Law: Foot and Mouth Disease. EFSA J 2021; 19:e06632. [PMID: 34136003 PMCID: PMC8185624 DOI: 10.2903/j.efsa.2021.6632] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases ('Animal Health Law'). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for foot and mouth disease (FMD). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: i) clinical and laboratory sampling procedures, ii) monitoring period and iii) the minimum radius of the protection and surveillance zones, and the minimum length of time the measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, the transmission kernels used for the assessment of the minimum radius of the protection zone of 3 km and of the surveillance zone of 10 km are shown. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. The monitoring period of 21 days was assessed as effective, and it was concluded that the protection and the surveillance zones comprise > 99% of the infections from an affected establishment if transmission occurred. Recommendations, provided for each of the scenarios assessed, aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to FMD.
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Kirkeby C, Brookes VJ, Ward MP, Dürr S, Halasa T. A Practical Introduction to Mechanistic Modeling of Disease Transmission in Veterinary Science. Front Vet Sci 2021; 7:546651. [PMID: 33575275 PMCID: PMC7870987 DOI: 10.3389/fvets.2020.546651] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 12/21/2020] [Indexed: 11/13/2022] Open
Abstract
Computer-based disease spread models are frequently used in veterinary science to simulate disease spread. They are used to predict the impacts of the disease, plan and assess surveillance, or control strategies, and provide insights about disease causation by comparing model outputs with real life data. There are many types of disease spread models, and here we present and describe the implementation of a particular type: individual-based models. Our aim is to provide a practical introduction to building individual-based disease spread models. We also introduce code examples with the goal to make these techniques more accessible to those who are new to the field. We describe the important steps in building such models before, during and after the programming stage, including model verification (to ensure that the model does what was intended), validation (to investigate whether the model results reflect the modeled system), and convergence analysis (to ensure models of endemic diseases are stable before outputs are collected). We also describe how sensitivity analysis can be used to assess the potential impact of uncertainty about model parameters. Finally, we provide an overview of some interesting recent developments in the field of disease spread models.
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Affiliation(s)
- Carsten Kirkeby
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark,*Correspondence: Carsten Kirkeby
| | - Victoria J. Brookes
- School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga, NSW, Australia,Graham Centre for Agricultural Innovation (Charles Sturt University and NSW Department of Primary Industries), Wagga, NSW, Australia
| | - Michael P. Ward
- Faculty of Veterinary Science, Sydney School of Veterinary Science, University of Sydney, Sydney, NSW, Australia
| | - Salome Dürr
- Department of Clinical Research and Public Health, Veterinary Public Health Institute, University of Bern, Bern, Switzerland
| | - Tariq Halasa
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
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Zaheer MU, Salman MD, Steneroden KK, Magzamen SL, Weber SE, Case S, Rao S. Challenges to the Application of Spatially Explicit Stochastic Simulation Models for Foot-and-Mouth Disease Control in Endemic Settings: A Systematic Review. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2020; 2020:7841941. [PMID: 33294003 PMCID: PMC7700052 DOI: 10.1155/2020/7841941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 10/20/2020] [Accepted: 10/30/2020] [Indexed: 11/17/2022]
Abstract
Simulation modeling has become common for estimating the spread of highly contagious animal diseases. Several models have been developed to mimic the spread of foot-and-mouth disease (FMD) in specific regions or countries, conduct risk assessment, analyze outbreaks using historical data or hypothetical scenarios, assist in policy decisions during epidemics, formulate preparedness plans, and evaluate economic impacts. Majority of the available FMD simulation models were designed for and applied in disease-free countries, while there has been limited use of such models in FMD endemic countries. This paper's objective was to report the findings from a study conducted to review the existing published original research literature on spatially explicit stochastic simulation (SESS) models of FMD spread, focusing on assessing these models for their potential use in endemic settings. The goal was to identify the specific components of endemic FMD needed to adapt these SESS models for their potential application in FMD endemic settings. This systematic review followed the PRISMA guidelines, and three databases were searched, which resulted in 1176 citations. Eighty citations finally met the inclusion criteria and were included in the qualitative synthesis, identifying nine unique SESS models. These SESS models were assessed for their potential application in endemic settings. The assessed SESS models can be adapted for use in FMD endemic countries by modifying the underlying code to include multiple cocirculating serotypes, routine prophylactic vaccination (RPV), and livestock population dynamics to more realistically mimic the endemic characteristics of FMD. The application of SESS models in endemic settings will help evaluate strategies for FMD control, which will improve livestock health, provide economic gains for producers, help alleviate poverty and hunger, and will complement efforts to achieve the Sustainable Development Goals.
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Affiliation(s)
- Muhammad Usman Zaheer
- Animal Population Health Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins CO 80523, USA
- FMD Project Office, Food and Agriculture Organization of the United Nations, ASI Premises, NARC Gate # 2, Park Road, Islamabad 44000, Pakistan
| | - Mo D. Salman
- Animal Population Health Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins CO 80523, USA
| | - Kay K. Steneroden
- Animal Population Health Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins CO 80523, USA
| | - Sheryl L. Magzamen
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins CO 80523, USA
| | - Stephen E. Weber
- Animal Population Health Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins CO 80523, USA
| | - Shaun Case
- Department of Civil and Environmental Engineering, Walter Scott, Jr. College of Engineering, Colorado State University, Fort Collins CO 80521, USA
| | - Sangeeta Rao
- Animal Population Health Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins CO 80523, USA
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Andraud M, Rose N. Modelling infectious viral diseases in swine populations: a state of the art. Porcine Health Manag 2020; 6:22. [PMID: 32843990 PMCID: PMC7439688 DOI: 10.1186/s40813-020-00160-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/25/2020] [Indexed: 02/06/2023] Open
Abstract
Mathematical modelling is nowadays a pivotal tool for infectious diseases studies, completing regular biological investigations. The rapid growth of computer technology allowed for development of computational tools to address biological issues that could not be unravelled in the past. The global understanding of viral disease dynamics requires to account for all interactions at all levels, from within-host to between-herd, to have all the keys for development of control measures. A literature review was performed to disentangle modelling frameworks according to their major objectives and methodologies. One hundred and seventeen articles published between 1994 and 2020 were found to meet our inclusion criteria, which were defined to target papers representative of studies dealing with models of viral infection dynamics in pigs. A first descriptive analysis, using bibliometric indexes, permitted to identify keywords strongly related to the study scopes. Modelling studies were focused on particular infectious agents, with a shared objective: to better understand the viral dynamics for appropriate control measure adaptation. In a second step, selected papers were analysed to disentangle the modelling structures according to the objectives of the studies. The system representation was highly dependent on the nature of the pathogens. Enzootic viruses, such as swine influenza or porcine reproductive and respiratory syndrome, were generally investigated at the herd scale to analyse the impact of husbandry practices and prophylactic measures on infection dynamics. Epizootic agents (classical swine fever, foot-and-mouth disease or African swine fever viruses) were mostly studied using spatio-temporal simulation tools, to investigate the efficiency of surveillance and control protocols, which are predetermined for regulated diseases. A huge effort was made on model parameterization through the development of specific studies and methodologies insuring the robustness of parameter values to feed simulation tools. Integrative modelling frameworks, from within-host to spatio-temporal models, is clearly on the way. This would allow to capture the complexity of individual biological variabilities and to assess their consequences on the whole system at the population level. This would offer the opportunity to test and evaluate in silico the efficiency of possible control measures targeting specific epidemiological units, from hosts to herds, either individually or through their contact networks. Such decision support tools represent a strength for stakeholders to help mitigating infectious diseases dynamics and limiting economic consequences.
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Affiliation(s)
- M. Andraud
- Anses, French Agency for Food, Environmental and Occupational Health & Safety, Ploufragan-Plouzané-Niort Laboratory, Epidemiology, Health and Welfare research unit, F22440 Ploufragan, France
| | - N. Rose
- Anses, French Agency for Food, Environmental and Occupational Health & Safety, Ploufragan-Plouzané-Niort Laboratory, Epidemiology, Health and Welfare research unit, F22440 Ploufragan, France
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Evaluation of human resources needed and comparison with human resources available to implement emergency vaccination in case of foot and mouth disease outbreaks in Tunisia. Epidemiol Infect 2020; 148:e128. [PMID: 32618526 PMCID: PMC7355213 DOI: 10.1017/s0950268820001284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Foot and mouth disease (FMD) is a highly contagious viral disease that affects domestic and wild artiodactyl animals and causes considerable economic losses related to outbreak management, production losses and trade impacts. In Tunisia, the last FMD outbreak took place in 2018-2019. The effectiveness of control measures implemented to control FMD depends, in particular, on the human resources used to implement them. Tunisia has the ultimate objective of obtaining OIE status as 'FMD-free with vaccination'. The aim of this study was to determine and compare the necessary and available human resources to control FMD outbreaks in Tunisia using emergency vaccination and to assess the gaps that would play a role in the implementation of the strategy. We developed a resources-requirement grid of necessary human resources for the management of the emergency vaccination campaign launched after the identification of a FMD-infected premises in Tunisia. Field surveys, conducted in the 24 governorates of Tunisia, allowed quantifying the available human resources for several categories of skills considered in the resources-requirement grid. For each governorate, we then compared available and necessary human resources to implement vaccination according to eight scenarios mixing generalised or cattle-targeted vaccination and different levels of human resources. The resources-requirement grid included 11 tasks in three groups: management of FMD-infected premises, organisational tasks and vaccination implementation. The available human resources for vaccination-related tasks included veterinarians and technicians from the public sector and appointed private veterinarians. The comparison of available and necessary human resources showed vaccination-related tasks to be the most time-consuming in terms of managing a FMD outbreak. Increasing the available human resources using appointed private veterinarians allowed performing the emergency vaccination of animals in the governorate in due time, especially if vaccination was targeted on cattle. The overall approach was validated by comparing the predicted and observed durations of a vaccination campaign conducted under the same conditions as during the 2014 Tunisian outbreak. This study could provide support to the Tunisian Veterinary Services or to other countries to optimise the management of a FMD outbreak.
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Halasa T, Ward MP, Boklund A. The impact of changing farm structure on foot-and-mouth disease spread and control: A simulation study. Transbound Emerg Dis 2020; 67:1633-1644. [PMID: 32012445 DOI: 10.1111/tbed.13500] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/19/2019] [Accepted: 01/27/2020] [Indexed: 11/29/2022]
Abstract
Foot-and-mouth disease (FMD) is a highly contagious viral disease that affects ruminants and pigs. Countries with large exports of livestock products are highly vulnerable to economic damage following an FMD incursion. The faster disease spread is controlled, the lower the economic damage. During the past decades, the structure of livestock production has dramatically changed. To maintain the relevance of contingency plans, it is important to understand the effects of changes in herd structure on the spread and control of infectious diseases. In this study, we compare the spread and control of FMD based on 2006/2007 and 2018 livestock data. Spread of FMD in Denmark was simulated using the DTU-DADS model, applying different control measures. The number of cattle, swine and sheep/goat herds reduced from about 50,000 in total in 2006/2007 to about 33,000 in 2018. During this period, the average number of outgoing animal movements and the exports of swine and swine products increased by about 35% and 22%, respectively. This coincided with an overall increase in herd size of 14%. Using the EU and national control measures (Basic: 3 days standstill, depopulation of detected herds followed by cleaning and disinfection and establishment of control zones, where tracing, surveillance and contact restrictions are implemented), we found that the simulated epidemics in 2018 would be about 50% shorter in duration, affect about 50% fewer herds but cause more economic damage, compared to epidemics using 2006/2007 data. When 2006/2007 data were used, Basic + pre-emptive depopulation (Depop) overall was the optimal control strategy. When 2018 data were used, this was the case only when epidemics were initiated in cattle herds, whereas when epidemics were initiated in sow or sheep/goats herds, basic performed as well as Depop. The results demonstrate that regular assessment of measures to control the spread of infectious diseases is necessary for contingency planning.
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Affiliation(s)
- Tariq Halasa
- Section for Animal Welfare and Disease Control, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Michael P Ward
- Sydney School of Veterinary Science, The University of Sydney, Camden, NSW, Australia
| | - Anette Boklund
- Section for Animal Welfare and Disease Control, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
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17
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Emergency Foot-and-Mouth Disease Vaccines A Malaysia 97 and A 22 Iraq 64 Offer Good Protection against Heterologous Challenge with A Variant Serotype A ASIA/G-IX/SEA-97 Lineage Virus. Vaccines (Basel) 2020; 8:vaccines8010080. [PMID: 32050709 PMCID: PMC7157217 DOI: 10.3390/vaccines8010080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/29/2020] [Accepted: 02/04/2020] [Indexed: 12/03/2022] Open
Abstract
The continuous emergence of foot-and-mouth disease virus (FMDV) serotype A variants in South East Asia is of concern for international FMDV antigen banks, especially when in vitro tests predict a low antigenic match. A vaccination-challenge study was performed by using two emergency FMDV vaccines with A22 Iraq 64 (A22 IRQ) and A Malaysia 97 (A MAY 97) strains, against challenge with a variant strain of FMDV A/Asia/G-IX/SEA-97 lineage at 7- and 21-day post-vaccination (dpv). At 7 dpv, three of five female calves vaccinated with A MAY 97 and four of five vaccinated with A22 IRQ did not show lesions on the feet and were considered protected, while at 21 dpv all five calves were protected with each vaccine, indicating equal efficacy of both vaccine strains. Calves were protected despite relatively low heterologous neutralizing antibody titers to the challenge virus at the time of challenge. All the calves developed antibodies to the non-structural proteins, most likely due to the direct intradermolingual (IDL) inoculation. Only one calf from the A MAY 97-7 group had infectious virus in the serum 1–3-day post-challenge (dpc), while no virus could be isolated from the serum of cattle challenged on 21 dpv. The virus could be isolated from the oral swabs of all calves, 1–7 dpc with viral RNA detected 1–10 dpc. Nasal swabs were positive for virus 1–6 dpc in a small number of calves. The time between vaccination and infection did not have an impact on the number of animals with persistent infection, with almost all the animals showing viral RNA in their oro-pharyngeal fluid (probang) samples up to 35 dpc. Despite the poor in vitro matching data and field reports of vaccine failures, this study suggests that these vaccine strains should be effective against this new A/Asia/G/SEA-97 variant, provided they are formulated with a high antigen dose.
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18
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Bradhurst R, Garner G, East I, Death C, Dodd A, Kompas T. Management strategies for vaccinated animals after an outbreak of foot-and-mouth disease and the impact on return to trade. PLoS One 2019; 14:e0223518. [PMID: 31603929 PMCID: PMC6788736 DOI: 10.1371/journal.pone.0223518] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 09/23/2019] [Indexed: 11/19/2022] Open
Abstract
An incursion of Foot-and-mouth disease (FMD) in a previously FMD-free country can cause significant economic damage from immediate and prolonged closure of FMD-sensitive markets. Whilst emergency vaccination may help contain disease, the presence of vaccinated animals complicates post-outbreak management and the recovery of FMD-free status for return to trade. We present enhancements to the Australian Animal DISease (AADIS) model that allow comparisons of post-outbreak management strategies for vaccinated animals, for the purposes of securing the earliest possible return to trade. Two case studies are provided that compare the retention of vaccinated animals with removal for waste/salvage, and the impact on recovery of FMD-sensitive markets per OIE guidelines. It was found that a vaccinate-and-retain strategy was associated with lower post-outbreak management costs, however this advantage was outweighed by significantly higher trade losses. Under the assumptions of the study there was no cost advantage to salvaging the removed vaccinated animals.
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Affiliation(s)
- Richard Bradhurst
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Parkville, VIC, Australia
- * E-mail:
| | - Graeme Garner
- Epidemiology and One Health, Animal Health Policy Branch, Department of Agriculture and Water Resources, Canberra, ACT, Australia
| | - Iain East
- Epidemiology and One Health, Animal Health Policy Branch, Department of Agriculture and Water Resources, Canberra, ACT, Australia
| | - Clare Death
- Epidemiology and One Health, Animal Health Policy Branch, Department of Agriculture and Water Resources, Canberra, ACT, Australia
| | - Aaron Dodd
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Parkville, VIC, Australia
| | - Tom Kompas
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne, Parkville, VIC, Australia
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19
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Fukai K, Nishi T, Morioka K, Yamada M, Yoshida K, Yamakawa M. Horizontal transmission of foot-and-mouth disease virus O/JPN/2010 among different animal species by direct contact. Transbound Emerg Dis 2019; 67:223-233. [PMID: 31482692 DOI: 10.1111/tbed.13344] [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: 09/02/2018] [Revised: 07/16/2019] [Accepted: 08/26/2019] [Indexed: 11/26/2022]
Abstract
Foot-and-mouth disease (FMD) is highly contagious and easily transmitted among species of cloven-hoofed animals. To investigate the transmission of FMD virus (FMDV) among different animal species, experimental infections using the O/JPN/2010 strain were performed in cows, goats and pigs. One cow or two goats/pigs were housed with a different species of inoculated animals, and clinical observations, virus shedding and antibody responses were analysed daily. Whilst all cows and goats were infected horizontally by contact with inoculated pigs, transmission from cows to goats/pigs and from goats to cows/pigs was not observed in all in-contact animals. In particular, no pigs were infected horizontally by contact with inoculated goats. Comparison with our previous study on experimental infections among animals of the same species indicates that horizontal transmission occurred more easily between animals of the same species than between those of the different species. These findings will be useful for establishing and performing species-specific countermeasures in farms and regions where multiple species of animals coexist in potential future outbreaks.
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Affiliation(s)
- Katsuhiko Fukai
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
| | - Tatsuya Nishi
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
| | - Kazuki Morioka
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
| | - Manabu Yamada
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
| | - Kazuo Yoshida
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
| | - Makoto Yamakawa
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Japan
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20
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Lee J, Ko Y, Jung E. Effective control measures considering spatial heterogeneity to mitigate the 2016-2017 avian influenza epidemic in the Republic of Korea. PLoS One 2019; 14:e0218202. [PMID: 31194835 PMCID: PMC6564009 DOI: 10.1371/journal.pone.0218202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/28/2019] [Indexed: 11/18/2022] Open
Abstract
During the winter of 2016-2017, an epidemic of highly pathogenic avian influenza (HPAI) led to high mortality in poultry and put a serious burden on the poultry industry of the Republic of Korea. Effective control measures considering spatial heterogeneity to mitigate the HPAI epidemic is still a challenging issue. Here we develop a spatial-temporal compartmental model that incorporates the culling rate as a function of the reported farms and farm density in each town. The epidemiological and geographical data of two species, chickens and ducks, from the farms in the sixteen towns in Eumseong-gun and Jincheon-gun are used to find the best-fitted parameters of the metapopulation model. The best culling radius to maximize the final size of the susceptible farms and minimize the total number of culled farms is calculated from the model. The local reproductive number using the next generation method is calculated as an indicator of virus transmission in a given area. Simulation results indicate that this parameter is strongly influenced not only by epidemiological factors such as transmissibility and/or susceptibility of poultry species but also by geographical and demographical factors such as the distribution of poultry farms (or density) and connectivity (or distance) between farms. Based on this result, we suggest the best culling radius with respect to the local reproductive number in a targeted area.
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Affiliation(s)
- Jonggul Lee
- National Institute for Mathematical Sciences, Daejeon, Republic of Korea
| | - Youngsuk Ko
- Mathematic department, Konkuk University, Seoul, Republic of Korea
| | - Eunok Jung
- Mathematic department, Konkuk University, Seoul, Republic of Korea
- * E-mail:
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21
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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.
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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
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22
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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.
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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
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Porphyre T, Rich KM, Auty HK. Assessing the Economic Impact of Vaccine Availability When Controlling Foot and Mouth Disease Outbreaks. Front Vet Sci 2018; 5:47. [PMID: 29594161 PMCID: PMC5859371 DOI: 10.3389/fvets.2018.00047] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/23/2018] [Indexed: 11/26/2022] Open
Abstract
Predictive models have been used extensively to assess the likely effectiveness of vaccination policies as part of control measures in the event of a foot and mouth disease (FMD) outbreak. However, the availability of vaccine stocks and the impact of vaccine availability on disease control strategies represent a key uncertainty when assessing potential control strategies. Using an epidemiological, spatially explicit, simulation model in combination with a direct cost calculator, we assessed how vaccine availability constraints may affect the economic benefit of a “vaccination-to-live” strategy during a FMD outbreak in Scotland, when implemented alongside culling of infected premises and dangerous contacts. We investigated the impact of vaccine stock size and restocking delays on epidemiological and economic outcomes. We also assessed delays in the initial decision to vaccinate, maximum daily vaccination capacity, and vaccine efficacy. For scenarios with conditions conducive to large outbreaks, all vaccination strategies perform better than the strategy where only culling is implemented. A stock of 200,000 doses, enough to vaccinate 12% of the Scottish cattle population, would be sufficient to maximize the relative benefits of vaccination, both epidemiologically and economically. However, this generates a wider variation in economic cost than if vaccination is not implemented, making outcomes harder to predict. The probability of direct costs exceeding £500 million is reduced when vaccination is used and is steadily reduced further as the size of initial vaccine stock increases. If only a suboptimal quantity of vaccine doses is initially available (100,000 doses), restocking delays of more than 2 weeks rapidly increase the cost of controlling outbreaks. Impacts of low vaccine availability or restocking delays are particularly aggravated by delays in the initial decision to vaccinate, or low vaccine efficacy. Our findings confirm that implementing an emergency vaccination-to-live strategy in addition to the conventional stamping out strategy is economically beneficial in scenarios with conditions conducive to large FMD outbreaks in Scotland. However, the size of the initial vaccine stock available at the start of the outbreak and the interplay with other factors, such as vaccine efficacy and delays in restocking or implementing vaccination, should be considered in making decisions about optimal control strategies for FMD outbreaks.
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Affiliation(s)
- Thibaud Porphyre
- Royal (Dick) School of Veterinary Studies, The Roslin Institute, University of Edinburgh, Midlothian, United Kingdom
| | - Karl M Rich
- Epidemiology Research Unit, Scotland's Rural College, Inverness, United Kingdom.,East and Southeast Asia Regional Office, International Livestock Research Institute, Hanoi, Vietnam
| | - Harriet K Auty
- Epidemiology Research Unit, Scotland's Rural College, Inverness, United Kingdom
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24
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Horsington J, Perez CB, Maradei E, Novo SG, Gonzales JL, Singanallur NB, Bonastre P, Vosloo W. Protective effects of high-potency FMDV O 1 Manisa monovalent vaccine in cattle challenged with FMDV O/SKR/2010 at 7 or 4 days post vaccination. Vaccine 2017; 35:5179-5185. [DOI: 10.1016/j.vaccine.2017.07.102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/16/2017] [Accepted: 07/27/2017] [Indexed: 10/19/2022]
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25
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Boklund A, Mortensen S, Johansen MH, Halasa T. Resource Estimations in Contingency Planning for Foot-and-Mouth Disease. Front Vet Sci 2017; 4:64. [PMID: 28553640 PMCID: PMC5425474 DOI: 10.3389/fvets.2017.00064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 04/19/2017] [Indexed: 11/24/2022] Open
Abstract
Preparedness planning for a veterinary crisis is important to be fast and effective in the eradication of disease. For countries with a large export of animals and animal products, each extra day in an epidemic will cost millions of Euros due to the closure of export markets. This is important for the Danish husbandry industry, especially the swine industry, which had an export of €4.4 billion in 2012. The purposes of this project were to (1) develop an iterative tool with the aim of estimating the resources needed during an outbreak of foot-and-mouth disease (FMD) in Denmark, (2) identify areas, which can delay the control of the disease. The tool developed should easily be updated, when knowledge is gained from other veterinary crises or during an outbreak of FMD. The stochastic simulation model DTU-DADS was used to simulate spread of FMD in Denmark. For each task occurring during an epidemic of FMD, the time and personnel needed per herd was estimated by a working group with expertise in contingency and crisis management. By combining this information, an iterative model was created to calculate the needed personnel on a daily basis during the epidemic. The needed personnel was predicted to peak within the first week with a requirement of approximately 123 (65–175) veterinarians, 33 (23–64) technicians, and 36 (26–49) administrative staff on day 2, while the personnel needed in the Danish Emergency Management Agency (responsible for the hygiene barrier and initial cleaning and disinfection of the farm) was predicted to be 174 (58–464), mostly recruits. The time needed for surveillance visits was predicted to be the most influential factor in the calculations. Based on results from a stochastic simulation model, it was possible to create an iterative model to estimate the requirements for personnel during an FMD outbreak in Denmark. The model can easily be adjusted, when new information on resources appears from management of other crisis or from new model runs.
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Affiliation(s)
- Anette Boklund
- Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | - Sten Mortensen
- The Danish Veterinary and Food Administration, Head Office, Glostrup, Denmark
| | | | - Tariq Halasa
- Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
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26
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Predicting the Ability of Preclinical Diagnosis To Improve Control of Farm-to-Farm Foot-and-Mouth Disease Transmission in Cattle. J Clin Microbiol 2017; 55:1671-1681. [PMID: 28330886 PMCID: PMC5442523 DOI: 10.1128/jcm.00179-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/11/2017] [Indexed: 12/04/2022] Open
Abstract
Foot-and-mouth disease (FMD) can cause large disruptive epidemics in livestock. Current eradication measures rely on the rapid clinical detection and removal of infected herds. Here, we evaluated the potential for preclinical diagnosis during reactive surveillance to reduce the risk of between-farm transmission. We used data from transmission experiments in cattle where both samples from individual animals, such as blood, probang samples, and saliva and nasal swabs, and herd-level samples, such as air samples, were taken daily during the course of infection. The sensitivity of each of these sample types for the detection of infected cattle during different phases of the early infection period was quantified. The results were incorporated into a mathematical model for FMD, in a cattle herd, to evaluate the impact of the early detection and culling of an infected herd on the infectious output. The latter was expressed as the between-herd reproduction ratio, Rh, where an effective surveillance approach would lead to a reduction in the Rh value to <1. Applying weekly surveillance, clinical inspection alone was found to be ineffective at blocking transmission. This was in contrast to the impact of weekly random sampling (i.e., using saliva swabs) of at least 10 animals per farm or daily air sampling (housed cattle), both of which were shown to reduce the Rh to <1. In conclusion, preclinical detection during outbreaks has the potential to allow earlier culling of infected herds and thereby reduce transmission and aid the control of epidemics.
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27
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Webb CT, Ferrari M, Lindström T, Carpenter T, Dürr S, Garner G, Jewell C, Stevenson M, Ward MP, Werkman M, Backer J, Tildesley M. Ensemble modelling and structured decision-making to support Emergency Disease Management. Prev Vet Med 2017; 138:124-133. [PMID: 28237227 DOI: 10.1016/j.prevetmed.2017.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 01/02/2017] [Indexed: 02/07/2023]
Abstract
Epidemiological models in animal health are commonly used as decision-support tools to understand the impact of various control actions on infection spread in susceptible populations. Different models contain different assumptions and parameterizations, and policy decisions might be improved by considering outputs from multiple models. However, a transparent decision-support framework to integrate outputs from multiple models is nascent in epidemiology. Ensemble modelling and structured decision-making integrate the outputs of multiple models, compare policy actions and support policy decision-making. We briefly review the epidemiological application of ensemble modelling and structured decision-making and illustrate the potential of these methods using foot and mouth disease (FMD) models. In case study one, we apply structured decision-making to compare five possible control actions across three FMD models and show which control actions and outbreak costs are robustly supported and which are impacted by model uncertainty. In case study two, we develop a methodology for weighting the outputs of different models and show how different weighting schemes may impact the choice of control action. Using these case studies, we broadly illustrate the potential of ensemble modelling and structured decision-making in epidemiology to provide better information for decision-making and outline necessary development of these methods for their further application.
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Affiliation(s)
- Colleen T Webb
- Department of Biology, Colorado State University, Fort Collins, CO, USA.
| | - Matthew Ferrari
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Tom Lindström
- Department of Biology, Colorado State University, Fort Collins, CO, USA; IFM, Theory and Modelling, Linköpings Universitet, Linköping, Sweden
| | - Tim Carpenter
- EpiCentre, Massey University, Palmerston North, New Zealand
| | - Salome Dürr
- Veterinary Public Health Institute, Vetsuisse Faculty, University of Berne, Switzerland
| | - Graeme Garner
- Animal Health Policy Branch, Department of Agriculture, Canberra, Australia
| | - Chris Jewell
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Mark Stevenson
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Michael P Ward
- Faculty of Veterinary Science, The University of Sydney, Camden, Australia
| | - Marleen Werkman
- Central Veterinary Institute part of Wageningen UR (CVI), Lelystad, The Netherlands
| | - Jantien Backer
- Central Veterinary Institute part of Wageningen UR (CVI), Lelystad, The Netherlands
| | - Michael Tildesley
- Warwick Infectious Disease Epidemiology Research (WIDER) Group, School of Life Sciences and Mathematics Institute, University of Warwick, Coventry, UK
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28
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Sanson RL, Rawdon T, Owen K, Hickey K, van Andel M, Yu ZD. Evaluating the benefits of vaccination when used in combination with stamping-out measures against hypothetical introductions of foot-and-mouth disease into New Zealand: a simulation study. N Z Vet J 2017; 65:124-133. [DOI: 10.1080/00480169.2016.1263165] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- RL Sanson
- AsureQuality Limited, PO Box 585, Palmerston North 4440, New Zealand
| | - T Rawdon
- Ministry for Primary Industries, Investigation Diagnostic Centres and Response Directorate, 25 The Terrace, Wellington, New Zealand
| | - K Owen
- Ministry for Primary Industries, Investigation Diagnostic Centres and Response Directorate, 25 The Terrace, Wellington, New Zealand
| | - K Hickey
- Ministry for Primary Industries, Investigation Diagnostic Centres and Response Directorate, 25 The Terrace, Wellington, New Zealand
| | - M van Andel
- Ministry for Primary Industries, Investigation Diagnostic Centres and Response Directorate, 25 The Terrace, Wellington, New Zealand
| | - ZD Yu
- Ministry for Primary Industries, Investigation Diagnostic Centres and Response Directorate, 25 The Terrace, Wellington, New Zealand
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29
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Garner MG, East IJ, Stevenson MA, Sanson RL, Rawdon TG, Bradhurst RA, Roche SE, Van Ha P, Kompas T. Early Decision Indicators for Foot-and-Mouth Disease Outbreaks in Non-Endemic Countries. Front Vet Sci 2016; 3:109. [PMID: 27965969 PMCID: PMC5127847 DOI: 10.3389/fvets.2016.00109] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/17/2016] [Indexed: 11/13/2022] Open
Abstract
Disease managers face many challenges when deciding on the most effective control strategy to manage an outbreak of foot-and-mouth disease (FMD). Decisions have to be made under conditions of uncertainty and where the situation is continually evolving. In addition, resources for control are often limited. A modeling study was carried out to identify characteristics measurable during the early phase of a FMD outbreak that might be useful as predictors of the total number of infected places, outbreak duration, and the total area under control (AUC). The study involved two modeling platforms in two countries (Australia and New Zealand) and encompassed a large number of incursion scenarios. Linear regression, classification and regression tree, and boosted regression tree analyses were used to quantify the predictive value of a set of parameters on three outcome variables of interest: the total number of infected places, outbreak duration, and the total AUC. The number of infected premises (IPs), number of pending culls, AUC, estimated dissemination ratio, and cattle density around the index herd at days 7, 14, and 21 following first detection were associated with each of the outcome variables. Regression models for the size of the AUC had the highest predictive value (R2 = 0.51-0.9) followed by the number of IPs (R2 = 0.3-0.75) and outbreak duration (R2 = 0.28-0.57). Predictability improved at later time points in the outbreak. Predictive regression models using various cut-points at day 14 to define small and large outbreaks had positive predictive values of 0.85-0.98 and negative predictive values of 0.52-0.91, with 79-97% of outbreaks correctly classified. On the strict assumption that each of the simulation models used in this study provide a realistic indication of the spread of FMD in animal populations. Our conclusion is that relatively simple metrics available early in a control program can be used to indicate the likely magnitude of an FMD outbreak under Australian and New Zealand conditions.
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Affiliation(s)
- Michael G Garner
- Animal Health Policy Branch, Department of Agriculture and Water Resources , Canberra, ACT , Australia
| | - Iain J East
- Animal Health Policy Branch, Department of Agriculture and Water Resources , Canberra, ACT , Australia
| | - Mark A Stevenson
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne , Parkville, VIC , Australia
| | | | - Thomas G Rawdon
- Investigation and Diagnostic Centre and Response Directorate, Ministry for Primary Industries , Wellington , New Zealand
| | - Richard A Bradhurst
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne , Parkville, VIC , Australia
| | - Sharon E Roche
- Animal Health Policy Branch, Department of Agriculture and Water Resources , Canberra, ACT , Australia
| | - Pham Van Ha
- Crawford School of Public Policy, Australian National University , Acton, ACT , Australia
| | - Tom Kompas
- Centre of Excellence for Biosecurity Risk Analysis, University of Melbourne , Parkville, VIC , Australia
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30
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Stenfeldt C, Pacheco JM, Brito BP, Moreno-Torres KI, Branan MA, Delgado AH, Rodriguez LL, Arzt J. Transmission of Foot-and-Mouth Disease Virus during the Incubation Period in Pigs. Front Vet Sci 2016; 3:105. [PMID: 27917386 PMCID: PMC5116750 DOI: 10.3389/fvets.2016.00105] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 11/07/2016] [Indexed: 11/13/2022] Open
Abstract
Understanding the quantitative characteristics of a pathogen’s capability to transmit during distinct phases of infection is important to enable accurate predictions of the spread and impact of a disease outbreak. In the current investigation, the potential for transmission of foot-and-mouth disease virus (FMDV) during the incubation (preclinical) period of infection was investigated in seven groups of pigs that were sequentially exposed to a group of donor pigs that were infected by simulated-natural inoculation. Contact-exposed pigs were comingled with infected donors through successive 8-h time slots spanning from 8 to 64 h post-inoculation (hpi) of the donor pigs. The transition from latent to infectious periods in the donor pigs was clearly defined by successful transmission of foot-and-mouth disease (FMD) to all contact pigs that were exposed to the donors from 24 hpi and later. This onset of infectiousness occurred concurrent with detection of viremia, but approximately 24 h prior to the first appearance of clinical signs of FMD in the donors. Thus, the latent period of infection ended approximately 24 h before the end of the incubation period. There were significant differences between contact-exposed groups in the time elapsed from virus exposure to the first detection of FMDV shedding, viremia, and clinical lesions. Specifically, the onset and progression of clinical FMD were more rapid in pigs that had been exposed to the donor pigs during more advanced phases of disease, suggesting that these animals had received a higher effective challenge dose. These results demonstrate transmission and dissemination of FMD within groups of pigs during the incubation period of infection. Furthermore, these findings suggest that under current conditions, shedding of FMDV in oropharyngeal fluids is a more precise proxy for FMDV infectiousness than clinical signs of infection. These findings may impact modeling of the propagation of FMD outbreaks that initiate in pig holdings and should be considered when designing FMD control strategies.
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Affiliation(s)
- Carolina Stenfeldt
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA; PIADC Research Participation Program, Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA
| | - Juan M Pacheco
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture , Greenport, NY , USA
| | - Barbara P Brito
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA; PIADC Research Participation Program, Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA
| | - Karla I Moreno-Torres
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA; PIADC Research Participation Program, Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA; Monitoring and Modeling, Animal and Plant Health Inspection Service, Center for Epidemiology and Animal Health, United States Department of Agriculture, Fort Collins, CO, USA
| | - Matt A Branan
- Monitoring and Modeling, Animal and Plant Health Inspection Service, Center for Epidemiology and Animal Health, United States Department of Agriculture , Fort Collins, CO , USA
| | - Amy H Delgado
- Monitoring and Modeling, Animal and Plant Health Inspection Service, Center for Epidemiology and Animal Health, United States Department of Agriculture , Fort Collins, CO , USA
| | - Luis L Rodriguez
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture , Greenport, NY , USA
| | - Jonathan Arzt
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture , Greenport, NY , USA
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31
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Knight-Jones TJD, Robinson L, Charleston B, Rodriguez LL, Gay CG, Sumption KJ, Vosloo W. Global Foot-and-Mouth Disease Research Update and Gap Analysis: 2 - Epidemiology, Wildlife and Economics. Transbound Emerg Dis 2016; 63 Suppl 1:14-29. [DOI: 10.1111/tbed.12522] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - L. L. Rodriguez
- Plum Island Animal Disease Center; ARS; USDA; Greenport New York USA
| | - C. G. Gay
- Agricultural Research Service; USDA; National Program 103-Animal Health; Beltsville MD USA
| | - K. J. Sumption
- European Commission for the Control of FMD (EuFMD); FAO; Rome Italy
| | - W. Vosloo
- Australian Animal Health Laboratory; CSIRO-Biosecurity Flagship; Geelong Vic Australia
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32
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Quantitative effects of a declaration of a state of emergency on foot-and-mouth disease. Environ Health Prev Med 2016; 21:237-47. [PMID: 27032773 DOI: 10.1007/s12199-016-0517-3] [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: 08/12/2015] [Accepted: 02/08/2016] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVES The law in Japan requires the declaration of a state of emergency and implementation of countermeasures for an epidemic of a new infectious disease. However, because a state of emergency has never been declared in Japan, its effects remain unknown. The required countermeasures are similar to those implemented in the foot-and-mouth disease epidemic in Miyazaki in 2010. This study aimed to quantitatively estimate the effect of the declaration in 2010 and investigate the nature of the epidemic based on the day on which the declaration took effect. METHODS Only publicly available data were used. Data for farms in the most affected town were analyzed. A modified susceptible-infected-recovered model was used to estimate the effect and for the simulation. Another model was used to estimate the effective reproduction number. RESULTS After the declaration, the intra-bovine transmission rate decreased by 18.1 %, and there were few days when the effective reproduction number was >1.0. A few weeks delay in the declaration significantly increased the possibility of epidemic, number of farms at peak, and final infection scale. CONCLUSIONS Based on the substantial decrease in the transmission rate after the declaration of a state of emergency in 2010, a future declaration will have a similar effect for a new infectious disease even though a direct extrapolation is not valid. Although a declaration should be carefully considered owing to the potential socioeconomic effects, it is essential to prepare for the implementation given that a delay of only a few weeks should be acceptable.
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33
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Zingg D, Häsler S, Schuepbach-Regula G, Schwermer H, Dürr S. Evidence for Emergency Vaccination Having Played a Crucial Role to Control the 1965/66 Foot-and-Mouth Disease Outbreak in Switzerland. Front Vet Sci 2015; 2:72. [PMID: 26697436 PMCID: PMC4677095 DOI: 10.3389/fvets.2015.00072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/26/2015] [Indexed: 11/23/2022] Open
Abstract
Foot-and-mouth disease (FMD) is a highly contagious disease that caused several large outbreaks in Europe in the last century. The last important outbreak in Switzerland took place in 1965/66 and affected more than 900 premises and more than 50,000 animals were slaughtered. Large-scale emergency vaccination of the cattle and pig population has been applied to control the epidemic. In recent years, many studies have used infectious disease models to assess the impact of different disease control measures, including models developed for diseases exotic for the specific region of interest. Often, the absence of real outbreak data makes a validation of such models impossible. This study aimed to evaluate whether a spatial, stochastic simulation model (the Davis Animal Disease Simulation model) can predict the course of a Swiss FMD epidemic based on the available historic input data on population structure, contact rates, epidemiology of the virus, and quality of the vaccine. In addition, the potential outcome of the 1965/66 FMD epidemic without application of vaccination was investigated. Comparing the model outcomes to reality, only the largest 10% of the simulated outbreaks approximated the number of animals being culled. However, the simulation model highly overestimated the number of culled premises. While the outbreak duration could not be well reproduced by the model compared to the 1965/66 epidemic, it was able to accurately estimate the size of the area infected. Without application of vaccination, the model predicted a much higher mean number of culled animals than with vaccination, demonstrating that vaccination was likely crucial in disease control for the Swiss FMD outbreak in 1965/66. The study demonstrated the feasibility to analyze historical outbreak data with modern analytical tools. However, it also confirmed that predicted epidemics from a most carefully parameterized model cannot integrate all eventualities of a real epidemic. Therefore, decision makers need to be aware that infectious disease models are useful tools to support the decision-making process but their results are not equal valuable as real observations and should always be interpreted with caution.
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Affiliation(s)
- Dana Zingg
- Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern , Bern , Switzerland
| | - Stephan Häsler
- Swiss Association for the History of Veterinary Medicine , Gasel , Switzerland
| | | | | | - Salome Dürr
- Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern , Bern , Switzerland
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34
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Probert WJM, Shea K, Fonnesbeck CJ, Runge MC, Carpenter TE, Dürr S, Garner MG, Harvey N, Stevenson MA, Webb CT, Werkman M, Tildesley MJ, Ferrari MJ. Decision-making for foot-and-mouth disease control: Objectives matter. Epidemics 2015; 15:10-9. [PMID: 27266845 DOI: 10.1016/j.epidem.2015.11.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/03/2015] [Accepted: 11/25/2015] [Indexed: 11/18/2022] Open
Abstract
Formal decision-analytic methods can be used to frame disease control problems, the first step of which is to define a clear and specific objective. We demonstrate the imperative of framing clearly-defined management objectives in finding optimal control actions for control of disease outbreaks. We illustrate an analysis that can be applied rapidly at the start of an outbreak when there are multiple stakeholders involved with potentially multiple objectives, and when there are also multiple disease models upon which to compare control actions. The output of our analysis frames subsequent discourse between policy-makers, modellers and other stakeholders, by highlighting areas of discord among different management objectives and also among different models used in the analysis. We illustrate this approach in the context of a hypothetical foot-and-mouth disease (FMD) outbreak in Cumbria, UK using outputs from five rigorously-studied simulation models of FMD spread. We present both relative rankings and relative performance of controls within each model and across a range of objectives. Results illustrate how control actions change across both the base metric used to measure management success and across the statistic used to rank control actions according to said metric. This work represents a first step towards reconciling the extensive modelling work on disease control problems with frameworks for structured decision making.
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Affiliation(s)
- William J M Probert
- Center for Infectious Disease Dynamics, Department of Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA, United States; Department of Biology and Intercollege Graduate Degree Program in Ecology, 208 Mueller Laboratory, The Pennsylvania State University, University Park, PA, United States; School of Veterinary Medicine and Science, University of Nottingham, Leicestershire LE12 5RD, United Kingdom.
| | - Katriona Shea
- Center for Infectious Disease Dynamics, Department of Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA, United States; Department of Biology and Intercollege Graduate Degree Program in Ecology, 208 Mueller Laboratory, The Pennsylvania State University, University Park, PA, United States
| | | | - Michael C Runge
- US Geological Survey, Patuxent Wildlife Research Center, 12100 Beech Forest Rd, Laurel, MD, United States
| | - Tim E Carpenter
- EpiCentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Salome Dürr
- Veterinary Public Health Institute, University of Bern, Bern, Switzerland
| | - M Graeme Garner
- Animal Health Policy Branch, Australian Government, Department of Agriculture, GPO Box 858, Canberra 2601, ACT, Australia
| | - Neil Harvey
- Department of Computing and Information Science, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Mark A Stevenson
- Faculty of Veterinary Science, University of Melbourne, Melbourne, VIC, Australia
| | - Colleen T Webb
- Department of Biology, Colorado State University, Fort Collins, CO, United States
| | - Marleen Werkman
- Central Veterinary Institute, Wageningen University and Research Centre, Houtribweg 39, 8221 RA Lelystad, The Netherlands; School of Veterinary Medicine and Science, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
| | - Michael J Tildesley
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
| | - Matthew J Ferrari
- Center for Infectious Disease Dynamics, Department of Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA, United States
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Halasa T, Toft N, Boklund A. Improving the Effect and Efficiency of FMD Control by Enlarging Protection or Surveillance Zones. Front Vet Sci 2015; 2:70. [PMID: 26664996 PMCID: PMC4675515 DOI: 10.3389/fvets.2015.00070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/20/2015] [Indexed: 11/13/2022] Open
Abstract
An epidemic of foot-and-mouth disease (FMD) in a FMD-free country with large exports of livestock and livestock products would result in profound economic damage. This could be reduced by rapid and efficient control of the disease spread. The objectives of this study were to estimate the economic impact of a hypothetical FMD outbreak in Denmark based on changes to the economic assumptions of the model, and to investigate whether the control of an FMD epidemic can be improved by combining the enlargement of protection or surveillance zones with pre-emptive depopulation or emergency vaccination. The stochastic spatial simulation model DTU-DADS was used to simulate the spread of FMD in Denmark. The control strategies were the basic EU and Danish strategy, pre-emptive depopulation, suppressive or protective vaccination, enlarging protection or surveillance zones, and a combination of pre-emptive depopulation or emergency vaccination with enlarged protection or surveillance zones. Herds are detected either based on basic detection through the appearance of clinical signs, or as a result of surveillance in the control zones. The economic analyses consisted of direct costs and export losses. Sensitivity analysis was performed on uncertain and potentially influential input parameters. Enlarging the surveillance zones from 10 to 15 km, combined with pre-emptive depopulation over a 1-km radius around detected herds resulted in the lowest total costs. This was still the case even when the different input parameters were changed in the sensitivity analysis. Changing the resources for clinical surveillance did not affect the epidemic consequences. In conclusion, an FMD epidemic in Denmark would have a larger economic impact on the agricultural sector than previously anticipated. Furthermore, the control of a potential FMD outbreak in Denmark may be improved by combining pre-emptive depopulation with an enlarged protection or surveillance zone.
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Affiliation(s)
- Tariq Halasa
- Section of Epidemiology, National Veterinary Institute, Technical University of Denmark , Copenhagen , Denmark
| | - Nils Toft
- Section of Epidemiology, National Veterinary Institute, Technical University of Denmark , Copenhagen , Denmark
| | - Anette Boklund
- Section of Epidemiology, National Veterinary Institute, Technical University of Denmark , Copenhagen , Denmark
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Hayama Y, Yamamoto T, Kobayashi S, Muroga N, Tsutsui T. Potential impact of species and livestock density on the epidemic size and effectiveness of control measures for foot-and-mouth disease in Japan. J Vet Med Sci 2015; 78:13-22. [PMID: 26256043 PMCID: PMC4751111 DOI: 10.1292/jvms.15-0224] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The characteristics of a livestock area, including farm density and animal species,
influence the spread of foot-and-mouth disease (FMD). In this study, the impact of
livestock area on FMD epidemics was examined using an FMD transmission model. For this
simulation, three major livestock areas were selected: the 2010 FMD epidemic area in Japan
as the baseline area (BS), a cattle and pig mixed production area (CP) and a cattle
production area (C). Simulation results demonstrated that under the 24-hr culling policy,
only 12% of epidemics among 1,000 simulations were abated within 100 days in the CP area,
whereas 90% of the epidemics ceased in the BS area. In the C area, all epidemics were
successfully contained within 100 days. Evaluation of additional control measures in the
CP area showed that the 0.5-km pre-emptive culling, even when only targeting pig farms,
raised the potential for successful containment to 94%. A 10-km vaccination on day 7 or 14
after initial detection was also effective in halting the epidemics (80%), but accompanied
a large number of culled or vaccinated farms. The combined strategy of 10-km vaccination
and 0.5-km pre-emptive culling targeting pig farms succeeded in containing all epidemics
within 100 days. The present study suggests the importance of preparedness for the 24-hr
culling policy and additional control measures when an FMD outbreak occurs in a densely
populated area. Considering the characteristics of the livestock area is important in
planning FMD control strategies.
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Affiliation(s)
- Yoko Hayama
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan
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Controlling highly pathogenic avian influenza outbreaks: An epidemiological and economic model analysis. Prev Vet Med 2015; 121:142-50. [PMID: 26087887 DOI: 10.1016/j.prevetmed.2015.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 06/02/2015] [Accepted: 06/04/2015] [Indexed: 11/23/2022]
Abstract
Outbreaks of highly pathogenic avian influenza (HPAI) can cause large losses for the poultry sector and for animal disease controlling authorities, as well as risks for animal and human welfare. In the current simulation approach epidemiological and economic models are combined to compare different strategies to control highly pathogenic avian influenza in Dutch poultry flocks. Evaluated control strategies are the minimum EU strategy (i.e., culling of infected flocks, transport regulations, tracing and screening of contact flocks, establishment of protection and surveillance zones), and additional control strategies comprising pre-emptive culling of all susceptible poultry flocks in an area around infected flocks (1 km, 3 km and 10 km) and emergency vaccination of all flocks except broilers around infected flocks (3 km). Simulation results indicate that the EU strategy is not sufficient to eradicate an epidemic in high density poultry areas. From an epidemiological point of view, this strategy is the least effective, while pre-emptive culling in 10 km radius is the most effective of the studied strategies. But these two strategies incur the highest costs due to long duration (EU strategy) and large-scale culling (pre-emptive culling in 10 km radius). Other analysed pre-emptive culling strategies (i.e., in 1 km and 3 km radius) are more effective than the analysed emergency vaccination strategy (in 3 km radius) in terms of duration and size of the epidemics, despite the assumed optimistic vaccination capacity of 20 farms per day. However, the total costs of these strategies differ only marginally. Extending the capacity for culling substantially reduces the duration, size and costs of the epidemic. This study demonstrates the strength of combining epidemiological and economic model analysis to gain insight in a range of consequences and thus to serve as a decision support tool in the control of HPAI epidemics.
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Lindström T, Tildesley M, Webb C. A Bayesian ensemble approach for epidemiological projections. PLoS Comput Biol 2015; 11:e1004187. [PMID: 25927892 PMCID: PMC4415763 DOI: 10.1371/journal.pcbi.1004187] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/11/2015] [Indexed: 12/14/2022] Open
Abstract
Mathematical models are powerful tools for epidemiology and can be used to compare control actions. However, different models and model parameterizations may provide different prediction of outcomes. In other fields of research, ensemble modeling has been used to combine multiple projections. We explore the possibility of applying such methods to epidemiology by adapting Bayesian techniques developed for climate forecasting. We exemplify the implementation with single model ensembles based on different parameterizations of the Warwick model run for the 2001 United Kingdom foot and mouth disease outbreak and compare the efficacy of different control actions. This allows us to investigate the effect that discrepancy among projections based on different modeling assumptions has on the ensemble prediction. A sensitivity analysis showed that the choice of prior can have a pronounced effect on the posterior estimates of quantities of interest, in particular for ensembles with large discrepancy among projections. However, by using a hierarchical extension of the method we show that prior sensitivity can be circumvented. We further extend the method to include a priori beliefs about different modeling assumptions and demonstrate that the effect of this can have different consequences depending on the discrepancy among projections. We propose that the method is a promising analytical tool for ensemble modeling of disease outbreaks.
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Affiliation(s)
- Tom Lindström
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
- Department of Biology, Colorado State University, Fort Collins, Colorado, United States of America
- US National Institute of Health, Bethesda, Maryland, United States of America
- University of Exeter, Exeter, United Kingdom
- * E-mail:
| | - Michael Tildesley
- US National Institute of Health, Bethesda, Maryland, United States of America
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Colleen Webb
- Department of Biology, Colorado State University, Fort Collins, Colorado, United States of America
- US National Institute of Health, Bethesda, Maryland, United States of America
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39
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The use of serosurveys following emergency vaccination, to recover the status of “foot-and-mouth disease free where vaccination is not practised”. Vaccine 2014; 32:7050-6. [DOI: 10.1016/j.vaccine.2014.10.064] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 10/20/2014] [Accepted: 10/26/2014] [Indexed: 11/21/2022]
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Gonzales JL, Barrientos MA, Quiroga JL, Ardaya D, Daza O, Martinez C, Orozco C, Crowther J, Paton DJ. Within herd transmission and evaluation of the performance of clinical and serological diagnosis of foot-and-mouth disease in partially immune cattle herds. Vaccine 2014; 32:6193-8. [PMID: 25261377 DOI: 10.1016/j.vaccine.2014.09.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/12/2014] [Accepted: 09/14/2014] [Indexed: 10/24/2022]
Abstract
The control of foot-and-mouth disease (FMD) in vaccinated populations relies upon surveillance activities such as clinical inspections (CI) and serological monitoring. New evidence to refine current surveillance guidelines has been provided by evaluating (1) the diagnostic performance of CI and serological tests for detection of FMD virus (FMDV) non-structural proteins (NSP), and (2) the within-herd transmission of the virus in partially immune cattle. Data came from 23 affected herds during an epidemic of FMDV type O in Bolivia, in 2007. All cattle (n=957) in these herds were clinically inspected and serum samples were collected one month after the last animal with clinical signs was detected. Samples were tested for the presence of antibodies against NSP using the PANAFTOSA 3ABC-ELISA test and a subset of samples were tested using the enzyme-linked immunoelectrotransfer blot assay (EITB). Data from clinical and serological diagnoses were analysed using a Bayesian model. The sensitivity Se and specificity Sp of the tests, as well as the prevalence and the within-herd reproduction ratio R of FMDV were estimated. In addition, risk factors for infection were identified. The Se of CI, the 3ABC-ELISA and the EITB tests were estimated to be 0.30, 0.88 and 0.96 respectively. The estimated Sp, in the same order, were 0.88, 0.93 and 0.97. The within-herd prevalence of infected animals ranged from 0.04 to 0.91 and R ranged from 1.02 to 2.68. It was observed that cattle coming from areas with high vaccination coverage had a lower risk of becoming infected than home-bred cattle from the affected herds, where vaccination coverage was thought to be low. Although these estimates come from herds kept under specific conditions, they provide a reference for future surveillance design and can inform simulation models for surveillance and control of FMD in similar cattle populations.
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Affiliation(s)
- J L Gonzales
- Unidad Nacional de Sanidad Animal, Servicion Nacional de Sanidad Animal y Ganaderia "SENASAG", Calle Natush Bush S/N, Trinidad, Bolivia; The Pirbright Institute, Ash road, GU24 0NF, Pirbright, Woking, UK.
| | - M A Barrientos
- Unidad Nacional de Sanidad Animal, Servicion Nacional de Sanidad Animal y Ganaderia "SENASAG", Calle Natush Bush S/N, Trinidad, Bolivia
| | - J L Quiroga
- Laboratorio de Investigacion y Diagnostico Veterinario LIDIVET, Av. Ejercito Nacional No 153, Santa Cruz, Bolivia
| | - D Ardaya
- Laboratorio de Investigacion y Diagnostico Veterinario LIDIVET, Av. Ejercito Nacional No 153, Santa Cruz, Bolivia
| | - O Daza
- Unidad Nacional de Sanidad Animal, Servicion Nacional de Sanidad Animal y Ganaderia "SENASAG", Calle Natush Bush S/N, Trinidad, Bolivia
| | - C Martinez
- Unidad Nacional de Sanidad Animal, Servicion Nacional de Sanidad Animal y Ganaderia "SENASAG", Calle Natush Bush S/N, Trinidad, Bolivia
| | | | | | - D J Paton
- The Pirbright Institute, Ash road, GU24 0NF, Pirbright, Woking, UK
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Evaluating vaccination strategies to control foot-and-mouth disease: a model comparison study. Epidemiol Infect 2014; 143:1256-75. [DOI: 10.1017/s0950268814001927] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SUMMARYSimulation models can offer valuable insights into the effectiveness of different control strategies and act as important decision support tools when comparing and evaluating outbreak scenarios and control strategies. An international modelling study was performed to compare a range of vaccination strategies in the control of foot-and-mouth disease (FMD). Modelling groups from five countries (Australia, New Zealand, USA, UK, The Netherlands) participated in the study. Vaccination is increasingly being recognized as a potentially important tool in the control of FMD, although there is considerable uncertainty as to how and when it should be used. We sought to compare model outputs and assess the effectiveness of different vaccination strategies in the control of FMD. Using a standardized outbreak scenario based on data from an FMD exercise in the UK in 2010, the study showed general agreement between respective models in terms of the effectiveness of vaccination. Under the scenario assumptions, all models demonstrated that vaccination with ‘stamping-out’ of infected premises led to a significant reduction in predicted epidemic size and duration compared to the ‘stamping-out’ strategy alone. For all models there were advantages in vaccinating cattle-only rather than all species, using 3-km vaccination rings immediately around infected premises, and starting vaccination earlier in the control programme. This study has shown that certain vaccination strategies are robust even to substantial differences in model configurations. This result should increase end-user confidence in conclusions drawn from model outputs. These results can be used to support and develop effective policies for FMD control.
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42
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Halasa T, Boklund A. The impact of resources for clinical surveillance on the control of a hypothetical foot-and-mouth disease epidemic in Denmark. PLoS One 2014; 9:e102480. [PMID: 25014351 PMCID: PMC4094525 DOI: 10.1371/journal.pone.0102480] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/05/2014] [Indexed: 11/29/2022] Open
Abstract
The objectives of this study were to assess whether current surveillance capacity is sufficient to fulfill EU and Danish regulations to control a hypothetical foot-and-mouth disease (FMD) epidemic in Denmark, and whether enlarging the protection and/or surveillance zones could minimize economic losses. The stochastic spatial simulation model DTU-DADS was further developed to simulate clinical surveillance of herds within the protection and surveillance zones and used to model spread of FMD between herds. A queuing system was included in the model, and based on daily surveillance capacity, which was 450 herds per day, it was decided whether herds appointed for surveillance would be surveyed on the current day or added to the queue. The model was run with a basic scenario representing the EU and Danish regulations, which includes a 3 km protection and 10 km surveillance zone around detected herds. In alternative scenarios, the protection zone was enlarged to 5 km, the surveillance zone was enlarged to 15 or 20 km, or a combined enlargement of the protection and surveillance zones was modelled. Sensitivity analysis included changing surveillance capacity to 200, 350 or 600 herds per day, frequency of repeated visits for herds in overlapping surveillance zones from every 14 days to every 7, 21 and 30 days, and the size of the zones combined with a surveillance capacity increased to 600 herds per day. The results showed that the default surveillance capacity is sufficient to survey herds on time. Extra resources for surveillance did not improve the situation, but fewer resources could result in larger epidemics and costs. Enlarging the protection zone was a better strategy than the basic scenario. Despite that enlarging the surveillance zone might result in shorter epidemic duration, and lower number of affected herds, it resulted frequently in larger economic losses.
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Affiliation(s)
- Tariq Halasa
- Section of Epidemiology, the National Veterinary Institutes, Technical University of Denmark, Copenhagen, Denmark
- * E-mail:
| | - Anette Boklund
- Section of Epidemiology, the National Veterinary Institutes, Technical University of Denmark, Copenhagen, Denmark
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43
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Farsang A, Frentzel H, Kulcsár G, Soós T. Control of the deliberate spread of foot-and-mouth disease virus. Biosecur Bioterror 2014; 11 Suppl 1:S115-22. [PMID: 23971796 DOI: 10.1089/bsp.2013.0001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Foot-and-mouth disease (FMD) is one of the most feared of transboundary animal diseases. Accidental or deliberate release of the causative agent can have both direct and indirect effects that result in massive economic losses and disruption. The direct effects of an FMD outbreak include immediate losses to agricultural production and disruption of local economies, while the indirect effects are mainly related to disease control measures such as restriction of market access at local and global levels and the high costs of disease control. To improve the capacity of the European Union (EU) to counter animal bioterrorism threats, AniBioThreat was launched with a special focus on threats to living animals, feed, and food of animal origin. As part of this project, several zoonotic or animal pathogenic agents are considered from different perspectives. FMD virus was selected as one agent to be scrutinized because it is highly contagious and an outbreak can have a severe economic impact. Ways to fight a deliberate outbreak can be demonstrated through the example of FMD. In this article, the virology and epidemiology of FMD virus are discussed with special attention to the related law enforcement aspects.
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44
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Elbers A, Knutsson R. Agroterrorism targeting livestock: a review with a focus on early detection systems. Biosecur Bioterror 2014; 11 Suppl 1:S25-35. [PMID: 23971814 DOI: 10.1089/bsp.2012.0068] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Agroterrorism targeting livestock can be described as the intentional introduction of an animal disease agent against livestock with the purpose of causing economic damage, disrupting socioeconomic stability of a country, and creating panic and distress. This type of terrorism can be alluring to terrorists because animal disease agents are easily available. This review addresses the vulnerabilities of the livestock industry to agroterrorism. However, we also show that early detection systems have recently been developed for agroterrorism and deliberate spread of animal pathogens in livestock, including an agroterrorism intelligence cycle, syndromic surveillance programs, and computer-based clinical decision support systems that can be used for early detection of notifiable animal diseases. The development of DIVA-vaccines in the past 10 to 15 years has created, in principle, an excellent response instrument to counter intentional animal disease outbreaks. These developments have made our animal agriculture less vulnerable to agroterrorism. But we cannot relax; there are still many challenges, in particular with respect to integration of first line of defense, law enforcement, and early detection systems for animal diseases.
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45
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Boqvist S, Dekker A, Depner K, Grace D, Hueston W, Stärk KDC, Sternberg Lewerin S. Contagious animal diseases: the science behind trade policies and standards. Vet J 2014; 202:7-10. [PMID: 25168718 DOI: 10.1016/j.tvjl.2014.06.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 06/23/2014] [Accepted: 06/26/2014] [Indexed: 11/17/2022]
Affiliation(s)
- S Boqvist
- Centre for Global Animal Diseases, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
| | - A Dekker
- Central Veterinary Institute, Lelystad, Wageningen UR, 8200 AB Lelystad, The Netherlands
| | - K Depner
- Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald-Insel Riems, Germany
| | - D Grace
- International Livestock Research Institute, Nairobi, Kenya
| | - W Hueston
- Center for Animal Health and Food Safety, University of Minnesota, 1354 Eckles Avenue, St Paul, Minnesota 22940, USA
| | - K D C Stärk
- Department of Production and Population Health, Royal Veterinary College, Hawkshead Lane, North Mymms AL9 7TA, UK
| | - S Sternberg Lewerin
- Centre for Global Animal Diseases, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
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Garner MG, Bombarderi N, Cozens M, Conway ML, Wright T, Paskin R, East IJ. Estimating Resource Requirements to Staff a Response to a Medium to Large Outbreak of Foot and Mouth Disease in Australia. Transbound Emerg Dis 2014; 63:e109-21. [DOI: 10.1111/tbed.12239] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Indexed: 11/29/2022]
Affiliation(s)
- M. G. Garner
- Department of Agriculture; Australian Government; Canberra ACT Australia
| | - N. Bombarderi
- Government of South Australia; Primary Industries and Regions; Glenside SA Australia
| | - M. Cozens
- Queensland Government; Department of Agriculture, Fisheries and Forestry; Nambour QLD Australia
| | - M. L. Conway
- Tasmanian Government; Department of Primary Industries, Parks, Water and Environment; Hobart TAS Australia
| | - T. Wright
- New South Wales Government; Department of Primary Industries; Orange NSW Australia
| | - R. Paskin
- Government of South Australia; Primary Industries and Regions; Glenside SA Australia
| | - I. J. East
- Department of Agriculture; Australian Government; Canberra ACT Australia
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47
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Sanson R, Dubé C, Cork S, Frederickson R, Morley C. Simulation modelling of a hypothetical introduction of foot-and-mouth disease into Alberta. Prev Vet Med 2014; 114:151-63. [DOI: 10.1016/j.prevetmed.2014.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 02/23/2014] [Accepted: 03/06/2014] [Indexed: 11/28/2022]
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48
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Bravo de Rueda C, de Jong MCM, Eblé PL, Dekker A. Estimation of the transmission of foot-and-mouth disease virus from infected sheep to cattle. Vet Res 2014; 45:58. [PMID: 24886222 PMCID: PMC4058432 DOI: 10.1186/1297-9716-45-58] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 04/30/2014] [Indexed: 11/21/2022] Open
Abstract
The quantitative role of sheep in the transmission of foot-and-mouth disease virus (FMDV) is not well known. To estimate the role of sheep in the transmission of FMDV, a direct contact transmission experiment with 10 groups of animals each consisting of 2 infected lambs and 1 contact calf was performed. Secretions and excretions (oral swabs, blood, urine, faeces and probang samples) from all animals were tested for the presence of FMDV by virus isolation (VI) and/or RT-PCR. Serum was tested for the presence of antibodies against FMDV. To estimate FMDV transmission, the VI, RT-PCR and serology results were used. The partial reproduction ratio R0p i.e. the average number of new infections caused by one infected sheep introduced into a population of susceptible cattle, was estimated using either data of the whole infection chain of the experimental epidemics (the transient state method) or the final sizes of the experimental epidemics (the final size method). Using the transient state method, R0p was estimated as 1.0 (95% CI 0.2 - 6.0) using virus isolation results and 1.4 (95% CI 0.3 - 8.0) using RT-PCR results. Using the final size method, R0p was estimated as 0.9 (95% CI 0.2 - 3.0). Finally, R0p was compared to the R0’s obtained in previous transmission studies with sheep or cattle only. This comparison showed that the infectivity of sheep is lower than that of cattle and that sheep and cattle are similarly susceptible to FMD. These results indicate that in a mixed population of sheep and cattle, sheep play a more limited role in the transmission of FMDV than cattle.
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Affiliation(s)
| | | | | | - Aldo Dekker
- Central Veterinary Institute (CVI), Wageningen UR, P,O, Box 65, 8200 AB, Lelystad, The Netherlands.
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49
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Halasa T, Boklund A, Stockmarr A, Enøe C, Christiansen LE. A comparison between two simulation models for spread of foot-and-mouth disease. PLoS One 2014; 9:e92521. [PMID: 24667525 PMCID: PMC3965434 DOI: 10.1371/journal.pone.0092521] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 02/23/2014] [Indexed: 11/30/2022] Open
Abstract
Two widely used simulation models of foot-and-mouth disease (FMD) were used in order to compare the models’ predictions in term of disease spread, consequence, and the ranking of the applied control strategies, and to discuss the effect of the way disease spread is modeled on the predicted outcomes of each model. The DTU-DADS (version 0.100), and ISP (version 2.001.11) were used to simulate a hypothetical spread of FMD in Denmark. Actual herd type, movements, and location data in the period 1st October 2006 and 30th September 2007 was used. The models simulated the spread of FMD using 3 different control scenarios: 1) A basic scenario representing EU and Danish control strategies, 2) pre-emptive depopulation of susceptible herds within a 500 meters radius around the detected herds, and 3) suppressive vaccination of susceptible herds within a 1,000 meters radius around the detected herds. Depopulation and vaccination started 14 days following the detection of the first infected herd. Five thousand index herds were selected randomly, of which there were 1,000 cattle herds located in high density cattle areas and 1,000 in low density cattle areas, 1,000 swine herds located in high density swine areas and 1,000 in low density swine areas, and 1,000 sheep herds. Generally, DTU-DADS predicted larger, longer duration and costlier epidemics than ISP, except when epidemics started in cattle herds located in high density cattle areas. ISP supported suppressive vaccination rather than pre-emptive depopulation, while DTU-DADS was indifferent to the alternative control strategies. Nonetheless, the absolute differences between control strategies were small making the choice of control strategy during an outbreak to be most likely based on practical reasons.
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Affiliation(s)
- Tariq Halasa
- Section of Epidemiology, The National Veterinary Institutes, Technical University of Denmark, Copenhagen, Denmark
- * E-mail:
| | - Anette Boklund
- Section of Epidemiology, The National Veterinary Institutes, Technical University of Denmark, Copenhagen, Denmark
| | - Anders Stockmarr
- Section of Epidemiology, The National Veterinary Institutes, Technical University of Denmark, Copenhagen, Denmark
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark
| | - Claes Enøe
- Section of Epidemiology, The National Veterinary Institutes, Technical University of Denmark, Copenhagen, Denmark
| | - Lasse E. Christiansen
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark
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50
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Roche S, Garner M, Wicks R, East I, de Witte K. How do resources influence control measures during a simulated outbreak of foot and mouth disease in Australia? Prev Vet Med 2014; 113:436-46. [DOI: 10.1016/j.prevetmed.2013.12.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 12/03/2013] [Accepted: 12/09/2013] [Indexed: 11/28/2022]
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