Analysis On Transmission Mechanism And Control Measures Of Avian Influenza And African Swine Fever

H7N9 avian influenza first appeared in East China in March 2013,and there have been five waves of outbreaks so far.By August 2020,the cumulative number of cases in China has exceeded 1568,and the mortality rate is about 39%.African swine fever(ASF)broke out for the first time in Shenyang,Liaoning,China in August 2018.As a highly infectious disease,its morbidity and mortality are very high.Due to the lack of effective vaccines and treatment methods to deal with it,the African swine fever epidemic spread to 23 regions in China in just four months.As of April 22,2019,129 ASF outbreaks have occurred in China,and 1.02 million pigs have been culled.Therefore,it is urgent to study the transmission mechanism and prevention and control measures of these two kinds of infectious diseases.Based on the dynamics model of infectious disease,this paper systematically analyzes the transmission characteristics of epidemic situation,so as to obtain the best prevention and control measures.Firstly,we propose a SI-V-SEIR dynamical model by considering the coupling effect of domestic poultry,H7N9 virus and human.Furthermore,the model with biological background parameters is numerically analyzed by Matlab to further quantify the intervention results for H7N9 infection,and the intervention results are comprehensively and systematically compared through numerical analysis to provide scientific prevention and control strategies for H7N9.The simulation results show that strict monitoring of poultry to prevent the invasion of H7N9 virus;vaccination of poultry needs to meet a certain proportion,when η>1-0.1λ_p can prevent the spread of H7N9 avian influenza virus;and limit poultry-to-poultry/human contacts can quickly prevent the spread of the disease;culling poultry can quickly reduce the risk of transmission but also cause a lot of economic losses;environmental disinfection can reduce the intensity of virus transmission but cannot eradicate the risk of infection,so need to cooperate with a variety of prevention and control measures to better eliminate the virus.Secondly,considering the interaction between pigs and the environment,we propose a SI-SEI transmission model,adding environmental variables,through the numerical analysis to obtain the impact of various transmission parameters on the spread of African swine fever and the equilibrium expression of the model is obtained.The Lyapunov function is constructed and the stability condition of the equilibrium is obtained by using the Routh-hurwitz Theorem.Matlab was used to fit the model with the real morbidity data of African swine fever in China.The simulation results show that reducing the contact between infected pigs and susceptible pigs is the top priority,and the suspected or confirmed farms should be treated harmlessly immediately to prevent further spread of the disease.In addition,it is also very important to strictly control and effectively clean and disinfect pig transport vehicles.The trend map of infection distribution from January to December was drawn by GIS,which showed that the incidence of infection was relatively high from February to April and from October to December in China,so protective measures should be taken in advance in early spring and late winter.