The Role of Imported Cases and Social-demographic Conditions in the Spatial Transmission of Dengue Epidemics

• Main Authors: Chieh-Ting Tsai, 蔡介庭
• Other Authors: Tzai-Hung Wen
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/15858471798670043037

碩士 === 國立臺灣大學 === 地理環境資源學研究所 === 102 === Dengue fever, a mosquito-borne disease, is an expanding public-health problem worldwide. One major research question involves the geographic expansion of such tropical diseases with global warming. Therefore, it is important to examine the relationship between imported cases and indigenous cases in epidemic regions. This pilot study took place in Taiwan. Air travel has brought more travelers from a dengue-endemic region, Southeast Asia, who have introduced virus strains that increase the risk of local epidemics in Taiwan. Past research has concentrated on meteorological data and ignored human behavior and socioeconomic conditions that influence dengue transmission at the meso- or micro-scale. The objective of this study is to examine the influences of socioeconomic conditions on the risk and speed of transmission. This study used origin-destination (OD) pairs to measure the risk and speed of transmission as dependent variables. Each OD pair was taken from cases of dengue fever in Taiwan between 2003 and 2012. The multiple-regression analysis included socioeconomic indicators, urbanization type, and past record of local emergence, as explanatory variables. The results showed that the risk of diffusion is correlated with the socioeconomic status of imported townships and with inverse distance between locations between July and December. Low average income in urbanized townships raised the risk of transmission of imported townships. Transmission speed was best explained by socioeconomic status of imported and local townships in late spring (from March to April). Higher population density in both imported and local townships was associated with increased transmission speeds, as was the pairing of low-average-income imported townships with higher-average-income local townships. In early summer (from May to June), higher population density was associated with lower transmission speeds. A predicted distribution of time lags shows the importance of urbanization with short time lags in late spring, though this effect disappeared in early summer. This study indicates that socioeconomic status of townships would influence transmission; however, the effect is limited to particular seasons, and the drivers are still unclear. Future research should focus on clarifying these relationships.