Foot-and-mouth disease (FMD) is one of the most contagious infectious diseases of domestic and wild cloven-hoofed animals, particular in cattle, sheep, pigs, goats and domestic buffalo, as well as wild ruminants such as deer. In Taiwan, there was a severe outbreak of FMD after more than 60 years freedom from the disease. The virus strain, O Taiwan 97 from the March 1997 outbreak of FMD in Taiwan, however, has been shown to have a species-specific adaptation to pigs. Although there are 7 distinct serotypes of FMD found in different regions of the world, this study focuses on the pig-adapted type O strain of FMD. After the FMD outbreak commenced in Taiwan, the spread of disease was very rapid and the whole of the western parts of Taiwan was affected within a few days after the diagnosis of FMD was confirmed. In some situations airborne transmission of FMD virus was suspected and it was speculated that this was the explanation for such rapid spread in Taiwan. Therefore, studies were conducted to investigate the transmissibility of O Taiwan/97 FMDV to susceptible pigs by direct and indirect spread including airborne spread in an enclosed animal house. This study showed that pigs in direct contact with challenged pigs became infected but none of the close-contact pigs became infected. These experiments clearly demonstrated that the pig adapted strain O Taiwan/97 was only efficiently transmitted by direct contact. This indicates that effective control against future outbreaks of pig adapted FMDV strains could be achieved by restriction of pig movement and stamping out if the outbreak has been detected in the early stages and prior to the movements of pigs from the infected premises. The measures used to control the Taiwanese FMD outbreak in 1997 were initially the slaughter of whole herds in the infected premises. However, with the rapid spread and large numbers of cases, the decision was taken to use universal compulsory vaccination of pig herds to control the outbreak when sufficient supply of vaccines was organized. Type O FMD vaccines were imported from a number of major FMD vaccine manufactures from around the world. Initially, vaccine efficacy for the imported vaccines was tested by measurement of neutralizing antibody titers in vaccinated pigs. To establish the relationship between serum neutralizing titers and protection from foot and mouth disease in pigs after vaccination, challenge studies were conducted with O/Taiwan/97 FMD in vaccinated pigs. Additionally, antibody responses to structural (neutralizing antibody) and non-structural proteins (NSP) were evaluated in vaccinated pig herds after primary and secondary vaccination in herds infected before and after vaccination. In order to be able to monitor the circulation of virus in vaccinated pig populations, valid diagnostic kits based on the detection of antibody against NSP were required. These tests needed to be evaluated against pig sera derived from challenge studies and natural FMD outbreaks. Three commercially available ELISAs (Cedi, UBI and Checkit), which were available to differentiate infected from vaccinated pigs, were tested and results showed that the Cedi test had the optimal sensitivity and specificity for pig adapted type O FMD testing. This test was used to retrospectively evaluate the sera collected from infected and non-infected pig herds collected sequentially in the year after the 1997 FMD outbreak in Taiwan. These studies also showed that the early vaccines used, stimulated NSP antibody production in swine herds that were vaccinated but not infected. This resulted in the requirement for purified FMD vaccines to be used when monitoring programs for FMD infection by NSP testing were in place. In these studies, it was also demonstrated that the purified FMD vaccines used later in the control program did not induce NSP antibody after multiple double dosage to pigs. Although clinical FMD appeared to be successfully controlled with vaccination program in Taiwan it was essential for the eradication plan to maintain active surveillance for NSP reactors in the pig population. The UBI and Cedi NSP kits were applied as screening and confirmatory tests, respectively, to pig sera collected in auction markets distributed around Taiwan to monitor for evidence of the circulation of FMD virus. Herds with positive reactors were followed-up by clinical inspection and 15 sera from suspected herds were further sampled. Negative results were obtained from all these investigation. With the absence of clinical outbreaks and the lack of evidence of FMDV circulation in the field from the NSP reactor surveillance, the Taiwanese government has progressed the eradication plan to a progressive cessation of vaccination, commencing with banning of vaccination on one isolated island in December 2006. The absence of outbreaks on that island, paved the way for further cessation of FMD vaccination in Taiwan from July 2008.

An outbreak of Foot and Mouth disease in Canada would result in the closing of borders to trade in meat and livestock between Canada and the US. The loss of export market access would result in losses to Canadian producers and negatively affect Canada’s reputation as a trading partner. Under a Regionalization Policy, trade could be allowed from disease-free regions of Canada during an outbreak. This would allow a limited amount of trade to continue and mitigate the losses to producers in uninfected areas. This thesis examined scenarios that involve various degrees of regionalization to determine the effects on producers, consumers and taxpayers. A partial- equilibrium model is used to determine the impact on economic welfare under each scenario and comparisons are made to help evaluate the relative outcomes of policies towards regionalization.

Foot and Mouth Disease (FMD) could have a significant impact on the U.S. agriculture industry and the welfare of U.S. producers and U.S. consumers. In order to address the potential impact from animal disease outbreaks, this project is designed to utilize a combined epidemic and economic modeling framework to evaluate animal disease management strategies which can be used to reduce the potential losses in an unusual event such as FMD outbreaks. In this study, we compare the welfare changes among three different parties with different strategies using, 1) ANOVA analysis; 2) cost benefit analysis; and 3) Risk Aversion Coefficient (RAC) analysis. Four types of index feedlots are selected in the study including, Feedlot Type 1 (> 50,000 heads of animals), Feedlot Type 4 (backgrounder feedlot), Large Beef Grazing (>100 heads of animals), and Backyard (<10 heads of animals). Results suggest that early detection of FMD events has the advantage in reducing risk as shown in the epidemiological impacts. Enhanced surveillance is found to be a preferred mitigation strategy for U.S. consumers in the scenario of smaller feedlot disease introductions (e.g. Large Beef Grazing and Backyard) and for U.S. producers in the larger feedlot disease introduction scenarios (e.g. Feedlot Type 1 and Feedlot Type 4). Adequate vaccination is not cost effective when seeking to minimize average loss but becomes a preferred strategy when the risk aversion rises. Risk modeling with stochastic programming adopted in this study also confirms the importance of incorporating risk evaluation into decision making process. It offers another option for us to evaluate the mitigation strategies. Two portfolio models are adopted in this study including, E-V model (mean variance portfolio choice model) and Unified model. The results show that the preference for control strategies depends on risk attitude. Early detection proves to be preferable for U.S. consumers and is also preferred by U.S. processors and producers as Risk Aversion Parameters (RAP) rises. Adequate vaccination strategy can benefit U.S. consumers but does not give U.S. processors a better outcome. Adequate vaccination provides a better choice for U.S. producers when the RAP rises. Enhanced surveillance is preferred for U.S. consumers. For U.S. processors, enhanced surveillance does not give a better risk/return outcome. U.S. producers are likely to switch their preferences from regular surveillance to enhanced surveillance as their RAP rises.

published_or_final_version / Zoology / Master / Master of Philosophy

Foot and mouth disease (FMD) is regarded as one of the greatest biological threats to the U.S. livestock industry because of its potential to cause catastrophic economic damages and massive livestock depopulation. Current U.S. contingency plans call for "stamping out" of FMD. An integral component of a "stamping out" policy is movement restrictions. The main purpose for movement restrictions is to stop the spread of disease, but they also disrupt the agribusiness sector. Welfare slaughter, the depopulation of healthy quarantined animals, is a possibility if movement restrictions are kept in place for prolonged periods of time. Many studies have analyzed the economic consequences of alternative mitigation strategies, but generally these studies have ignored the costs that might arise because of movement restrictions affecting uninfected premises located within the quarantine zone. Ultimately this study seeks to improve preparedness in the event of a FMD outbreak. It does this by developing information for those formulating plans on the costs associated with movement restrictions regarding quarantined, uninfected large feedlots located in the Texas High Plains Region. To accomplish this objective two strategies were compared: an unrestricted feed strategy, where feed is allowed to be brought onto uninfected premises and finished cattle are sold; and a welfare slaughter strategy, where feed isn't allowed to be brought onto the uninfected premises so animals are depopulated. In addition, seasonal differences in total costs were examined. This study expanded on the High Plains Study conducted by M. Ward, L. Highfield, P. Vongseng, and M. Garner by using their epidemiological data combined with a cost accounting framework to estimate the total cost of each strategy. This study examined direct disease management costs (indemnity payments, feed costs, marketing costs, surveillance costs, cleaning and disinfecting costs, appraisal cost, euthanasia costs, and disposal costs). Overall, the unrestricted feed strategy was less expensive than the welfare slaughter strategy, costing on average $22.6 million compared to $48.5 million, respectively. Disease outbreak timing did impact the overall cost of both strategies. The results suggest the policy makers should strongly consider creating movement policies that address feed supply and finished cattle movement for uninfected large feedlots in prolonged quarantine zones; as such policies appear to reduce outbreak related costs for stakeholder and the U.S. government.

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Thesis (MSc (Veterinary Tropical Diseases))--University of Pretoria, 2008. / Includes bibliographical references. Also available in print format.

Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

No description available.

No description available.