Browsing by Subject "Bovine tuberculosis"

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    Evaluation Of Control Strategies For Eradication Of Bovine Tuberculosis In Endemic Settings
    (2019-05) Picasso-Risso, Catalina
    Bovine tuberculosis (bTB) is an infectious disease of cattle that has an important impact in animal and public health. In spite of many efforts and resources invested in its eradication, bTB is still endemic in many countries. The intradermal tuberculin test- and- slaughter of bTB positive animals, with the slaughter surveillance, are the basis of bTB-control and eradication programs in place. However, the accuracy of intradermal testing tends to vary broadly with factors inherent to the country and to the individual immunity of the animal. In Uruguay, in spite of many efforts dedicated to bTB eradication, this disease has reached unprecedented prevalence levels in large, intensified dairy systems in the past years (2010-2018). This raised concerns regarding the suitability of the bTB-control strategies to reach eradication in this evolving demographic and management scenarios. In this dissertation we aimed to assess current and alternative control strategies for bTB in high-prevalence endemic settings, considering the identified demographic and management risk factors, to guide the design and implementation of optimal control and eradication procedures through mathematical modeling. Overall, we demonstrate that JD has an effect in bTB-diagnostic results at the herd and individual level in high prevalence bTB and JD coinfected populations studied, which needs to be addressed in the planning of bTB-control programs, specifically in regards of the performance of the bTB-diagnostic tools used. Still, in this co-infected scenario, the use of IGRA notably improved the sensitivity of detection in these herds, which can be beneficial in declining initial high bTB-prevalence levels. However, it is crucial to incorporate bTB-testing in young animals (<12 months) to break disease transmission and achieve eradication. Further studies would be required in order to determine the best bTB-control strategy resulting from the interaction between bTB- and JD- epidemiology, test performance, and economic costs, while acknowledging the country logistics and socio-cultural perceptions. Nevertheless, this research represents the first attempt to integrate field risk factors for the diagnosis of bTB, and JD-coinfection in the design of control strategies for heavily infected herds that can be the foundation of optimal bTB-control strategies to reach eradication when depopulation is not suitable.
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    Understanding animal movements to inform bovine tuberculosis surveillance: a framework for a targeted approach
    (2013-08) do Rosario Ribeiro Lima, Joao Paulo
    Bovine tuberculosis (bTB) is a zoonotic disease that affects domestic and wildlife species. In recent years in the US, a novel scenario for bTB has arisen, characterized by sporadic outbreaks in cattle populations across the country and by spillover of the infection to wildlife. The cattle production system in the US continues to change, with the number of cattle farms declining but the number of cattle per farm increasing. Furthermore, cattle are moved long distances for trade and production purposes. Also the drought has encouraged a large number of cattle to move from severely affected southern states to northern states, such as Minnesota with available feed and water resources. This reality poses a threat to the biosecurity of the Minnesota cattle population and agricultural industry, due to the risk of introduction of bTB from which the state is now free. The objective of the studies presented here was to develop a new framework for bTB surveillance based on risk profiling of herds and regions. The fundamental concept from which the current work originates is that infectious disease transmission is not a random process but is modulated by risk factors that enhance its occurrence. The primarily concern in disease-free areas such as the state of Minnesota should be the identification of those key players, in this case farms and/or regions, that are at higher risk of disease introduction, and secondly to identify those farms and/or regions that would cause greater impact in the cattle population and wildlife populations if infected. The ultimate goal is to develop a targeted approach to bTB surveillance in order to increase system accuracy and cost-effectiveness which, although effective in the past, has failed recently to prevent continuing outbreaks in US cattle and wildlife populations. The combination of the studies presented in this doctoral dissertation provides a systems approach to bTB surveillance, especially at the wildlife and cattle interface. It develops a framework for a targeted surveillance system by developing approaches to identify at risk cattle premises and regions where disease is both more likely to be introduced and spread.