Abstract
BackgroundSouthern Taiwan has been a hotspot for dengue fever transmission since 1998. During 2014 and 2015, Taiwan experienced unprecedented dengue outbreaks and the causes are poorly understood. This study aims to investigate the influence of regional and local climate conditions on the incidence of dengue fever in Taiwan, as well as to develop a climate-based model for future forecasting.Methodology/Principle findingsHistorical time-series data on dengue outbreaks in southern Taiwan from 1998 to 2015 were investigated. Local climate variables were analyzed using a distributed lag non-linear model (DLNM), and the model of best fit was used to predict dengue incidence between 2013 and 2015. The cross-wavelet coherence approach was used to evaluate the regional El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) effects on dengue incidence and local climate variables. The DLNM results highlighted the important non-linear and lag effects of minimum temperature and precipitation. Minimum temperature above 23°C or below 17°C can increase dengue incidence rate with lag effects of 10 to 15 weeks. Moderate to high precipitation can increase dengue incidence rates with a lag of 10 or 20 weeks. The model of best fit successfully predicted dengue transmission between 2013 and 2015. The prediction accuracy ranged from 0.7 to 0.9, depending on the number of weeks ahead of the prediction. ENSO and IOD were associated with nonstationary inter-annual patterns of dengue transmission. IOD had a greater impact on the seasonality of local climate conditions.Conclusions/SignificanceOur findings suggest that dengue transmission can be affected by regional and local climatic fluctuations in southern Taiwan. The climate-based model developed in this study can provide important information for dengue early warning systems in Taiwan. Local climate conditions might be influenced by ENSO and IOD, to result in unusual dengue outbreaks.
Highlights
Dengue Fever (DF) is an important vector-borne disease that is mainly transmitted in tropical and subtropical regions by several Aedes species of mosquito
The highest annual minimum temperatures during the study period were observed in 2015, which might be related to the strong El Niño Southern Oscillation (ENSO) event that year (S2 Table)
Previous studies conducted in Asia and Latin America have revealed the importance of climate conditions in dengue transmission [54,55,56,57]
Summary
Dengue Fever (DF) is an important vector-borne disease that is mainly transmitted in tropical and subtropical regions by several Aedes species of mosquito. Aedes aegypti (Linnaeus) is considered the main vector for dengue transmission in urban regions, and Aedes albopictus (Skuse) is considered the secondary and more rural vector [1]. The incidence of dengue is increasing, and has reached an estimated 390 million annual cases, of which 96 million present with clinical symptoms [2, 3]. The concurrent circulation of different serotypes increases the risk of severe clinical outcomes and is a huge concern for public health. Southern Taiwan has been a hotspot for dengue fever transmission since 1998. This study aims to investigate the influence of regional and local climate conditions on the incidence of dengue fever in Taiwan, as well as to develop a climatebased model for future forecasting.
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