Simulating Intra-urban Dengue Transmission And Interventions

As one of the most threatened mosquito-borne diseases in the world,dengue fever has grown dramatically around the world in recent decades.Simulating dengue outbreak is important for understanding the transmission mechanism of dengue fever and thus to make better prevention strategies.As human mobility is one of the key factors for the spread of infectious diseases,however,the existing models that use a small amount of travel survey data and gravity models to simulate human movements has some limitations such as low sampling rates and inaccuracy.Second,a large number of aymptomatic infected people in the crowd play an important role in the transmission of dengue fever,but many studies have ignored this important factor,which led to the model cannot realistically simulate the spread of dengue fever.Therefore,an accurate dengue transmission model with more realistic human movements and taking into account aymptomatic infected people is urgently required.Aiming at the urgently requirement above,in this study,we proposed a spatially explicit,individual-based model based on multisource trajectory data to simulate dengue transmission in an intra-urban environment,which can make up for its limitations.The multisource trajectory data composed of large-scale mobile phone location data and travel survey data used in this study can more realistically simulate individual movements in cities,thereby supporting more accurate simulation of dengue spread and prevention and control strategies.In addition,for a large number of asymptomatic import cases during the transmission of dengue fever,we design three scenarios to explore the most likely spatial distribution of asymptomatic infections.Taking the dengue outbreak of Shenzhen,China in 2014 as a study case,the simulation results suggest that our proposed spatially explicit,individual-based model can well reproduce the spatio-temporal patterns of the dengue outbreak.It also indicates that when the spatial distribution of asymptomatic imported cases is consistent with the symptomatic imported cases,the model behaves best that the simulated spatio-temporal distribution of dengue cases matches well with the reality,thus indicates that asymptomatic import cases are always co-occurrence with symptomatic cases.At the same time,according to the dengue transmission model proposed in this study,three dengue prevention and control strategies were simulated.The dengue prevention and control strategies are dengue vaccination program,isolation of symptomatic infected persons and precision mosquito control strategies.The simulation results show that the intervention of dengue vaccination program is the most effective prevention and control method for dengue.When the proportion of vaccination is 60%,it can reduce about 96.53% of the infected people,and the number of new infected people per day does not exceed two,effectively preventing the spread of dengue virus;secondly,isolation of symptomatic infected people can significantly reduce the number of dengue infected people about 81.80%%.However,it is necessary to grasp the time of isolation strategy,if the time of strategy is too late,the prevention and control effect will be greatly reduced;finally,for mosquito control measures commonly used in dengue control,precise implementation of killing mosquitos can reduce the risk of dengue fever transmission to a limited extent.When the ratio of mosquito control is 100%,the number of infected people will be reduced by 64.94%.However,compared with dengue vaccination programs and isolation measures,the mosquito control measures is less effectives.When the strategy of isolating symptomatic infected persons and precision mosquito control is adopted at the same time,the number of infected persons decreases by 85.51%.However,considering that dengue vaccines are currently unavailable,the recommended prevention and control strategy is joint prevention and control of isolating infected persons and controlling mosquitoes precisely,thereby reducing the risk of dengue fever spreading.The main contributions of this study mostly lies in:(1)The spatially explicit,individual-based model based on multisource trajectory data can more accurately describe the micro individual interaction,reduce the uncertainty of temporal and spatial,fully consider the population heterogeneity,and support more accurate dengue transmission and intervention strategy simulation;(2)Combined with the spatially explicit,individual-based model based on multisource trajectory data,three dengue intervention strategies including dengue fever vaccine plan,isolation of symptomatic infected persons and precise mosquito control were simulated and evaluated,and the current best prevention and control strategies were recommended through analysis of simulation results,which can provide scientific guidance for the development of dengue fever prevention and control strategies within the city.(3)It is the first time to explore the influence of the spatial location of asymptomatic import cases on the transmission of dengue fever,the results found that the most likely spatial distribution of asymptomatic import cases is consistent with the symptomatic input cases,which can strengthen the understanding of dengue fever asymptomatic patients.(4)Through the prevention and control strategy results,it's shows that the joint prevention and control strategies of isolation and precise mosquito control is the best strategy for dengue fever.Overall,this study provides an effective spatially explicit,individual-based model that not only can accurately simulate the spatio-temporal characteristics of dengue at a fine scale,and provides deeper understanding of the asymptomatic cases,but also allows various dengue intervention simulations more refined at the individual level,which can help guide policy-making to control dengue outbreaks at an urban scale.