Increasingly expanded future risk of dengue fever in the Pearl River Delta, China

Background: In recent years, frequent outbreaks of dengue fever (DF) have become an increasingly serious public health issue in China, especially in the Pearl River Delta (PRD) with fast socioeconomic developments. Previous studies mainly focused on the historic DF epidemics, their influencing factors, and the prediction of DF risks. However, the future risks of this disease under both different socioeconomic development and representative concentration pathways (RCPs) scenarios remain little understood. Methodology and principal findings: In this study, a spatial dataset of gross domestic product (GDP), population density, and land use and land coverage (LULC) in 2050 and 2070 was obtained by simulation based on the different shared socioeconomic pathways (SSPs), and the future climatic data derived from the RCP scenarios were integrated into the Maxent models for predicting the future DF risk in the PRD region. Among all the variables included in this study, socioeconomics factors made the dominant contribution (83% or so) during simulating the current spatial distribution of the DF epidemics in the PRD region. Moreover, the spatial distribution of future DF risk identified by the climatic and socioeconomic (C&S) variables models was more detailed than that of the climatic variables models. Along with global warming and socioeconomic development, the zones with DF high and moderate risk will continue to increase, and the population at high and moderate risk will reach a maximum of 48.47 million (i.e., 63.78% of the whole PRD) under the RCP 4.5/SSP2 in 2070. Conclusions: The increasing DF risk may be an inevitable public health threat in the PRD region with rapid socioeconomic developments and global warming in the future. Our results suggest that curbs in emissions and more sustainable socioeconomic growth targets offer hope for limiting the future impact of dengue, and effective prevention and control need to continue to be strengthened at the junction of Guangzhou-Foshan, north-central Zhongshan city, and central-western Dongguan city. Our study provides useful clues for relevant hygienic authorities making targeted adapting strategies for this disease. Author summary: As the most prevalent mosquito-borne infection in the world, the dengue fever (DF) outbreaks were increasingly serious in China in recent years. In particular, almost 85% of the total cases in the mainland China were reported in the PRD region, which has been attributed in previous studies to its suitable subtropical climate with hot, wet summers and mild autumns, as well as the highest urbanization, crowded and large floating population in some informal urban settlements. In consideration of an expected rapid socioeconomic development in the PRD region in the future, the climatic and socioeconomic variables were comprehensively integrated into the ecological niche models (ENM) for projecting the spatial distribution of DF risk in 2050 and 2070. The results showed that more detailed geographic distribution of DF risk zones (grids) was appropriately identified for the current and future scenarios through the models aggregating both climatic and socioeconomic variables. In comparison, the socioeconomic variables presented better capability of identifying the risk zones in detail. Along with continuously rapid socioeconomic development and global warming in the future, the PRD region may be confronted by increasing zones and population of high/moderate DF risk, as well as their spatial expansion during the 2050 and 2070. Accordingly, a forward-looking public health planning should be appropriately made so as to address the DF risk posed by global warming and the expected socioeconomic growth in this region in the future.