A Study On The Spread Model And Spatial Distribution Of Hfmd Based On Gis

This thesis studies the spread mechanism of Hand-Foot-Mouth disease (HFMD), and then discusses why it happens; To predict the transmission trend of HFMD, mathematical model of HFMD is established. The spatial distribution of HFMD is studied so as to reveal its distribution pattern and to detect its incidence hotspots.Taking population density, river network density, the number of preschools, annual average temperature, annual average precipitation and the incidence of previous year as independent variables ,the method of step by step regression is used to filtrate important indexes .After eliminating multicollinearity among indexes, the spatial autoregressive model of HFMD is established in GeoDa ,using the remaining variables of river network density, the number of preschools, annual average precipitation, the incidence of previous year as independent variables ,with which the correlation between HFMD spread and external factors is studied to reveal its spreading mechanism. Using the four independent variables filtrated above, geographically weighted regression model is established in ArcGis , with which spatial variation of the impact of the four indexes to HFMD spread in various townships and neighborhoods is studied to reveal the corresponding sensitivity factors of HFMD spread in various townships and neighborhoods. According to the disease ecology of HFMD, this thesis puts forward the hypothesis of the prevalence track of HFMD and designs some relational parameters and as well estimates the value of these parameters based on the epidemic situation data. On such a basis, we establish the sub-SEIS model of HFMD, further more, we deduce and constitute a differential eguation and solve the equations set. Using the disease information, we make many kinds of simulations to predict the trend of HFMD spread, then we make the further transmission dynamics analyses .With HFMD case data from 1st January 2008 to 31st August 2009 , the latest population data and Ningbo vector map of 1:20000, the spatial distribution of spatio-temporal variation, aggregation features and directional features of HFMD are studied by global spatial autocorrelation method and local spatial autocorrelation method in ArcGis.The spatial autoregressive model reveals river network density, the number of preschools, annual average precipitation and the incidence of previous year ,those four indexes can explain 77.48% of the variance explained of HFMD spread, the spread of HFMD has significant correlation with the four indexes mentioned above. The geographically weighted regression model reveals those four indexes affecting the spread of HFMD exist spatial variation in various townships and neighborhoods. The Goodness-of-Fit of geographically weighted regression model is higher than global model in the southern Fenghua, Ninghai and Xiangshan areas, while the Goodness-of-Fit of the local model is less than the global model in Yuci district, city youngest area and Beilun, Zhenhai and other regions, where HFMD spread may also be affected by other factors (such as economic activities and epidemic external input). The actual outbreak fitting results show that the sub-SEIS model established can be used to describe the overall trend of HFMD, and can predict the next few days, the daily incidence and cumulative number of cases. The spatial autocorrelation analysis reveals that the spatial distribution of HFMD exists low-value aggregation and high-value aggregation, and in years of high incidence of the disease, the spatial distribution of HFMD in Ningbo has a certain stability, that is, the direction of high incidence of disease (North-west 26 degrees) and the direction of low incidence of disease (North-east 64 degrees) basically remain stable.