Weather variables and the El Nino Southern Oscillation may drive the epidemics of dengue in Guangdong Province, China

Objective: To investigate the periodicity of dengue and the relationship between weather variables, El Nino Southern Oscillation (ENSO) and dengue incidence in Guangdong Province, China. Methods: Guangdong monthly dengue incidence and weather data and El Nino index information for 1988 to 2015 were collected. Wavelet analysis was used to investigate the periodicity of dengue, and the coherence and time-lag phases between dengue and weather variables and ENSO. The Generalized Additive Model (GAM) approach was further employed to explore the dose-response relationship of those variables on dengue. Finally, random forest analysis was applied to measure the relative importance of the climate predictors. Results: Dengue in Guangdong has a dominant annual periodicity over the period 1988-2015. Mean minimum temperature, total precipitation, and mean relative humidity are positively related to dengue incidence for 2, 3, and 4 months lag, respectively. ENSO in the previous 12 months may have driven the dengue epidemics in 1995, 2002. 2006 and 2010 in Guangdong. GAM analysis indicates an approximate linear association for the temperature-dengue relationship, approximate logarithm curve for the humidity-dengue relationship, and an inverted U-shape association for the precipitation-dengue (the threshold of precipitation is 348 mm per month) and ENSO-dengue relationships (the threshold of ENSO index is 0.6 degrees C). The monthly mean minimum temperature in the previous two months was identified as the most important climate variable associated with dengue epidemics in Guangdong Province. Conclusion: Our study suggests weather factors and ENSO are important predictors of dengue incidence. These findings provide useful evidence for early warning systems to help to respond to the global expansion of dengue fever. (C) 2017 Elsevier B.V. All rights reserved.