Browsing by Subject "Foot and mouth disease"

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    A framework for the evaluation of strategies to reduce risk of foot and mouth disease transmission associated with the trade of beef from East African cattle systems: a progressive and participatory approach
    (2021-09) Adamchick, Julie
    granularity needed in places that tend to have diverse and informal value chains, and b) tapping into unwritten local knowledge / subject matter expertise in a way that generated credible information in a format that can be used for quantitative analysis. The dual training-research activity was also a beneficial experience for participants to model and analyze a problem and system from their professional work. The second aim was to estimate the probability (risk) of FMD at slaughter under current conditions -- the baseline risk. This required quantifying input values and distributions for the variables identified in aim one and translating the conceptual relationships into a probabilistic mathematical model. The risk estimates and sensitivity analyses provided insight about influential factors that could be leveraged to lower the probability of FMD among beef cattle at slaughter from select populations. The third and final aim was to evaluate the cost-effectiveness of possible interventions that could reduce risk in specific value chains. Scenarios were generated using the insights from aim two and compared based on estimated costs and level of risk expected to achieve. This provided insight about specific steps that could be taken as well as a more general gradient of what scale of risk reduction might be expected from a given investment. This information can be combined with information about benefits, limitations, and tradeoffs to support decisions about investments related to FMD control and ambitions for international trade. The output and process of this work provide useful contributions to improve decision-making regarding investments for animal health and trade in regions with endemic trade-sensitive diseases. In Kenya, a feedlot-focused, abattoir-partnered approach may reach the lowest achievable risk. Specific opportunities need to be evaluated in terms of the capacity of necessary stakeholders, cost of sanitary and traceability investments, costs of production, and competitiveness of the resulting product. In both Kenya and Uganda, regionally-focused investments that combined livestock identification and traceability systems with vaccination among willing producers in partnership with an ambitious export abattoir improve FMD control and animal health while reducing risk in the product produced and taking steps toward foundational traceability and disease control capacity. The framework of incremental progress with a focus on risk of the final commodity complements the Progressive Control Pathway for FMD, providing a way to benchmark slow and steady forward motion, and should be used to evaluate disease control and SPS interventions that intend to achieve market access. Participatory approaches that embed data collection for decision analysis into training opportunities for local professionals are a rich way to improve the quality of data and analysis while also building capacity of participants to appreciate the complexity of systems in which they work and the value of analytical approaches to decision-making. Key findings from each chapter: • Aim 1 (chapter 3): o Risk processes differ between management systems, with an especially clear delineation in Kenya between agro-pastoral/pastoral and ranching/feedlot system groups-- highlighting the important interactions between management factors and health or risk dynamics. o FMD infection and sale for slaughter are not always independent events for cattle in Kenya and Uganda, suggesting it would be judicious to characterize the relationship between sale and disease of cattle in the population of study when examining the movement or sale of animals in endemic environments. o The motivations and actions of value chain actors influence the ultimate risk level in a product, demonstrated through the need to include a distinct event for whether or not a disease event is reported after a positive diagnosis. • Aim 2 (chapter 4): o The overall risk of FMD infection at slaughter was substantially lower for cattle originating from Kenyan feedlots and ranches compared to the other six systems evaluated. o In Uganda, semi-intensive and ranching systems showed the potential to reach similarly low risk levels if able to severely limit the exposure to new infections after leaving the herd. o Reduction or elimination of commingling before slaughter was the most effective intervention to reduce risk of infection at slaughter for most systems. o For Kenyan ranches, the detection and removal of infected animals was identified as a potentially important point for intervention. • Aim 3 (chapter 5): o Preventive mass vaccination was the least cost-effective strategy evaluated, even for a relatively small region. It would require a relatively high investment for not the best return with many obstacles on the path, and may not be an advisable strategy especially for the purpose of targeting export opportunities. o Strategies that involved voluntary rather than compulsory participation had more favorable cost-effectiveness ratios. o The greatest reduction in risk at the lowest cost was obtained through a voluntary program that combined a livestock ID and traceability system with biannual preventive vaccination and a premium price at slaughter for participants.
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    Self-reporting of risk pathways and parameter values for foot and mouth disease in slaughter cattle from alternative production systems by Kenyan and Ugandan veterinarians
    (2021-08) Adamchick, Julie; Rich, Karl M.; Perez, Andres M.
    Countries in which foot and mouth disease (FMD) is endemic may face bans on the export of FMD-susceptible livestock and products because of the associated risk for transmission of FMD virus. Risk assessment is an essential tool for demonstrating the fitness of one’s goods for the international marketplace and for improving animal health. However, it is difficult to obtain the necessary data for such risk assessments in many countries where FMD is present. This study bridged the gaps of traditional participatory and expert elicitation approaches by partnering with veterinarians from the National Veterinary Services of Kenya (n=13) and Uganda (n=10) enrolled in an extended capacity-building program to systematically collect rich, local knowledge in a format appropriate for formal quantitative analysis. Participants mapped risk pathways and quantified variables that determine the risk of infection among cattle at slaughter originating from each of four beef production systems in each country. Findings highlighted that risk processes differ between management systems, that disease and sale are not always independent events, and that events on the risk pathway are influenced by the actions and motivations of value chain actors. The results provide necessary information for evaluating the risk of FMD among cattle pre-harvest in Kenya and Uganda and provide a framework for similar evaluation in other endemic settings.
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    The use of movement data and network models to measure the effectiveness of control strategies for foot-and-mouth disease in swine
    (2018-11) Kinsley, Amy
    Foot-and-mouth disease has been considered a significant epidemic threat to livestock since the sixteenth century, hindering animal health and leading to direct and indirect economic losses through treatment, decreased productivity, trade restrictions, and disease control programs. The disease is caused by infection with foot-and-mouth disease virus (FMDV), which belongs to the Aphthovirus genus and the family Picornavirdae. There are several main serotypes circulating throughout the world, with numerous subtypes creating challenges for global eradication. In the event of a of foot-and-mouth disease (FMD) incursion into an FMD-free country, response strategies are required to control, contain and eradicate the pathogen as efficiently as possible. Simulation models have often been used to test the effectiveness and efficiency of alternative control strategies to mitigate the spread of infectious animal diseases and have contributed greatly to advancements in our understanding of disease transmission. However, quantitative values on the duration of the stages of FMD infection, within-farm transmission dynamics, and understanding between-farm movement patterns are all essential components in using simulation models in livestock populations. In this thesis, we quantified values associated with the duration of the stages of FMD infection (latent period, subclinical period, incubation period, and duration of infection), probability of transmission (within-herd and between-herd via spatial spread), and time to the diagnosis of a vesicular disease within a herd using a meta-analysis of peer-reviewed literature and expert opinion. We then assessed the impact of farm structure (different barns or rooms for breeding and gestation, farrowing, nursery, and finishing) and demography (piglet births and deaths, and animal movement within and off of the farm) by testing the impact of assuming a homogeneous mixing/closed population, a common assumption for within-farm models of highly contagious diseases of swine, such as foot-and-mouth disease (FMD), on predictions about disease spread. Looking beyond within-farm dynamics, we described the annual movement patterns between swine farms in three production systems of the United States and identified farms that may be targeted to increase the efficacy of infectious disease control strategies. We then used the results from the within-farm model and analysis of movement patterns to understand the impact of using empirical movement data compared to simulated movement data and compared targeted control strategies using metrics of the movement data to control strategies that are based on geographical factors such as zones and rings. The results worth highlighting from of our investigations include the following: Chapter 2: When quantifying the duration of the stages of FMD infection in swine, we found that the latent period and the incubation period ranged from 1 to 7 days and 1 to 9 days, respectively. Furthermore, we found that distribution of those values is dependent on the strain of FMDV, in which some strains have a shorter latent period and incubation period than others, which should be considered when modeling FMD transmission. Chapter 3: In this chapter, we incorporated farm structure and demography in to the within-herd model and observed transmission dynamics that differed in the latter portion of an outbreak in certain conditions. Specifically, we observed that farm structure and demography, which were included in the farrow to finish and farrow to wean farms, resulted in FMD virus persistence within the population, which can have significant impacts on between-farm spread. Chapter 4: Through our analysis of empirical movement data, we showed that targeting farms based on a metric that captured the temporal sequence of movements (mean infection potential), substantially reduced the potential for transmission of an infectious pathogen in the contact network and performed consistently well across production systems. This result highlights the importance of detailed movement data in understanding potential disease spread within production systems. Chapter 5: In this chapter we modeled the impact of alternative control strategies on between-farm transmission of FMD, we saw that control strategies, which preemptively targeted specific farms based on their spatial network, reduced the number of infected farms, duration of the epidemic, number of vaccinated farms, and the number of culled farms when compared to reactive scenarios that used the formation of rings and zones around infected-detected farms.