The Modeling Study On The Transmission,prevention And Control Of Zoonotic And Highly Pathogenic Avian Influenza

The Zoonotic and Highly Pathogenic Avian Influenza Virus(ZHPAIV)not only induces disease leading to mortality in birds,impairs the sustainability of the poultry industry,but also poses a significant threat to public health by causing human infections.To fortify the avian flu control system,promote the development of public health,and enhance societal and economic benefits,this dissertation employs dynamical modeling and investigates the impact of the behaviors of human and wild birds on the transmission of the disease,and proposes economical and effective strategies.To explore the effect of human behavior on the transmission of the disease,we establish a two-patch avian-human epidemic model that characterizes two behavioral changes induced by the epidemic: reduced contact with infection sources and engagement in illegal live poultry trade.By computing the control reproduction numbers for high-risk,low-risk and overall regions,we analyze the transmission dynamics of the model.The results reveal that when illegal live poultry trade occurs and the reproduction number in high-risk regions exceed one,the disease will be prevalent in both patches.However,it will be prevalent only if the reproduction numbers in both high and low-risk regions exceed one in the absence of illegal live poultry trade indicating that human behavior is one of the risk factors promoting the transmission of the disease.To prevent such malpractices,we examine the game of stakeholders in the live poultry value chain.Our findings indicate that a Nash culling subsidy exists when the culling subsidy and illegal trade fines equal illegal trade profits.The omission in prevention and control of the disease is put forward and corresponding suggestions are given.Besides humans,wild birds are also one of the primary hosts of the viruses,and their migratory behavior affects the transmission of the disease.Based on wild bird’s migratory behavior,we establish a reaction-diffusion-advection model involving wild birds,poultry and humans.We mainly investigate the impact of the spatio-temporal overlap between wild birds and poultry on the transmission of the disease and reveal the spatio-temporal evolution laws of the disease.By the next-generation operator theory,we obtain the basic reproduction number of the model and demonstrate threshold dynamics.Subsequently,utilizing the spatio-temporal overlap between North American wild blue-winged ducks and domestic poultry,we examine the impact of key parameters on the basic reproduction number.The findings underscore that the basic reproduction number is more significantly influenced by the behavior of wild birds.Moreover,we simulate the spatio-temporal variations in the number of infected poultry and the human population,investigate the impact of avian behavior on the transmission of disease,and identify risk points during the process of transmission.These revelations serve as a theoretical basis for the prevention and control of ZHPAIV.Poultry culling is a primary measure to curb the spread of avian flu.Previous research employed a linear function to characterize culling measures.However,when the capacities or resources are limited,a saturation culling function is more practical.Hence,we focus on the transmission mechanism among poultry and humans and establish a dynamic model with a saturation culling function.Through the analysis,we find that the model shows complex dynamic behaviors,such as saddle-node bifurcation,transcritical bifurcation and Hopf bifurcation,and so on.The results reveal that saturation culling is a mild method and insufficient for eradicating the disease.Furthermore,in the pursuit of exploring economical and effective strategies for ZHPAIV,a multi-objective optimization problem is constructed with the main measures of poultry vaccination,culling and closure of live poultry markets,with the purpose of minimizing the infection size and the cost due to the disease.By the optimal control theory,the characteristics of the solution to this optimization problem have been defined.Numerical simulations show that closure of live poultry markets and vaccination are more cost-effective measures than culling.