Lagged temperature effect with mosquito transmission potential explains dengue variability in southern Taiwan

The purpose of this study was to link meteorological factors and mosquito (Aedes aegypti) abundance to examine the potential effects of climate variations on patterns of dengue epidemiology in Taiwan during 2001-2008. Spearman's rank correlation tests with and without time-lag were performed to investigate the overall correlation between dengue incidence rates and meteorological variables (i.e., minimum, mean, and maximum temperatures, relative humidity (RH), and rainfall) and percentage Breteau index (BI) level > 2 in Taipei and Kaohsiung of northern and southern Taiwan, respectively. A Poisson regression analysis was performed by using a generalized estimating equations (GEE) approach. The most parsimonious model was selected based on the quasi-likelihood based information criterion (QICu). Spearman's rank correlation tests revealed marginally positive trends in the weekly mean (ρ=0.28, p<0.0001), maximum (ρ=0.26,p<0.0001), and minimum (ρ=0.30,p<0.0001) temperatures in Taipei. However, in Kaohsiung, all negative trends were found in the weekly mean (ρ= -0.32,p<0.0001), maximum (ρ=-0.30,p<0.0001), and minimum (ρ=.-0.32, p<0.0001) temperatures. This study concluded that based on the GEE approach, rainfall, minimum temperature, and RH, all with 3-month lag, and 1-month lag of percentage BI level >2 are the significant predictors of dengue incidence in Kaohsiung (QICu=ρ277.77). This study suggested that warmer temperature with 3-month lag, elevated humidity with high mosquito density increased the transmission rate of human dengue fever infection in southern Taiwan.