An Exploratory Study Of The Relationship Between Human Brucellosis And Animal Brucellosis Epidemic And The Control Measures Based On Differential Equations

Objective: Brucellosis is a common zoonotic disease that can cause a large number of human cases around the world every year,posing a serious threat to public health and the development of animal husbandry.In China,the incidence of human brucellosis shows an overall increasing trend during the past years.Differential equations have been applied more and more widely in the simulation of infectious diseases transmission dynamic,and have played an increasingly important role in the prevention and control of infectious diseases.In order to control the spread of brucellosis in China and explore the transmission characteristics of brucellosis in depth,this paper used differential kinetic equations to further explore the spreading dynamics of brucellosis among cattle,sheep and human population.With the help of differential kinetic equations,the efficacy and the cost-effectiveness of the prevention and control measures against brucellosis were also studied.Methods: The temporal and spatial distribution of human brucellosis,seasonal characteristics of brucellosis and the brucellosis incidence in different age groups in mainland China between 2004 and 2017 were described.Data regarding the human brucellosis incidence and seroprevalence of cattle and sheep in China between 2005 and2018 were selected to establish a data set,and the data set was further divided into training and testing sets to train and test the model,respectively.Based on the SEIR compartmental model,two kinds of differential kinetic equation models were established to simulate the onset of brucellosis in humans and evaluate the effects of the prevention and control interventions.Disability Adjusted Life Years(DALYs)was used to estimate the burden of brucellosis on human health and the indirect economic burden nationwide.The costs of the prevention and control measures against brucellosis were estimated and the cost-effectiveness analysis was conducted to determine the feasibility of those measures.Results: 1.From 2004 to 2017,the incidence of brucellosis among the provinces and municipalities in mainland China was the highest in the second quarter of each year(April-June),and the lowest in the fourth quarter(October-December).Except for theincidence of brucellosis in the Tibet Autonomous Region showing a downward trend,the incidence in other provinces and municipalities showed an upward trend.Brucellosis mainly occurred in the northern provinces of China,and the incidence of brucellosis in southern provinces was relatively lower.2.From 2004 to 2017,the number of brucellosis cases in all age groups showed an upward trend.The 30-59 age group had the largest number of cases,accounting for 70% of the total number of cases.The average disease burden of brucellosis was about 5175 DALYs(0.00383 DALYs/1000 people),and the average indirect economic burden was 129 million yuan.The health burden and economic burden caused by brucellosis on mainland Chinese residents were generally on the rise.3.The simulation results of the differential dynamic equation model showed that the S2 vaccine,environmental disinfection and protection against susceptible animals and susceptible humans could reverse the increasing incidence of brucellosis and lower the incidence of human brucellosis to further bring the prevalence of brucellosis under control.When the vaccine coverage rate was 30%,50% and 80%,the cost-effectiveness ratio of vaccination during the simulation period was less than three times the GDP per capita;when the protection rate of the susceptible population was 10% and 50%respectively,the cost-effectiveness ratio of the protection of the susceptible during the simulation period was less than three times the GDP per capita;when the times of environmental disinfection ranged from once every four weeks,once every two weeks,and once a week,the cost-effectiveness ratio of environmental disinfection during the simulation period was less than three times the GDP per capita.Conclusion: 1.From 2004 to 2017,brucellosis was highly prevalent in the northern provinces of China,and the incidence rate in southern provinces showed an increasing trend year by year.2.Brucellosis produced a serious indirect economic burden on Chinese residents.The disease burden(DALYs)and the indirect economic burden generally showed an upward trend from 2004 to 2017.3.Cattle and sheep infected during the latent period after exposure were able to discharge the pathogen to the outside world,but could possibly not directly infect susceptible animals and susceptible people.4.The S2 vaccine could reduce the incidence of brucellosis in humans.The expansion of the immunity coverage rate could further control the brucellosis epidemic.Environmental disinfection,protection of the susceptible,and health education couldeffectively control the incidence of brucellosis in the future.5.Vaccine immunization,regular environmental disinfection and sterilization,and the protection of susceptible people were cost-effective preventive interventions.