Increasing Dengue Incidence in Singapore over the Past 40 Years: Population Growth, Climate and Mobility

Abstract

In Singapore, the frequency and magnitude of dengue epidemics have increased significantly over the past 40 years. It is important to understand the main drivers for the rapid increase in dengue incidence. We studied the relative contributions of putative drivers for the rise of dengue in Singapore: population growth, climate parameters and international air passenger arrivals from dengue endemic countries, for the time period of 1974 until 2011. We used multivariable Poisson regression models with the following predictors: Annual Population Size; Aedes Premises Index; Mean Annual Temperature; Minimum and Maximum Temperature Recorded in each year; Annual Precipitation and Annual Number of Air Passengers arriving from dengue-endemic South-East Asia to Singapore. The relative risk (RR) of the increase in dengue incidence due to population growth over the study period was 42.7, while the climate variables (mean and minimum temperature) together explained an RR of 7.1 (RR defined as risk at the end of the time period relative to the beginning and goodness of fit associated with the model leading to these estimates assessed by pseudo-R2 equal to 0.83). Estimating the extent of the contribution of these individual factors on the increasing dengue incidence, we found that population growth contributed to 86% while the residual 14% was explained by increase in temperature. We found no correlation with incoming air passenger arrivals into Singapore from dengue endemic countries. Our findings have significant implications for predicting future trends of the dengue epidemics given the rapid urbanization with population growth in many dengue endemic countries. It is time for policy-makers and the scientific community alike to pay more attention to the negative impact of urbanization and urban climate on diseases such as dengue.

A Spatial Hierarchical Analysis of the Temporal Influences of the El Niño-Southern Oscillation and Weather on Dengue in Kalutara District, Sri Lanka

“…Therefore, further studies on the impact of climatic factors on both regional and national dengue incidence are essential to understand what actions are needed to control the disease under aggravated conditions of climate variability and change. At the same time, it is important to consider how other factors, such as urbanization and population density [29], effectiveness of dengue control measures, viral genetic configuration, immunity status of the population and population mobility [66], co-facilitate dengue epidemics in order to strengthen dengue surveillance at local and global levels and reduce its public health burden.…”

“…The risk of dengue transmission can increase with elevated temperatures by increasing the reproductive rate and biting rate of vectors and the probability of human to vector transmission per bite, as well as by reducing the extrinsic incubation period [12,21,26,27]. Other important factors affecting dengue epidemiology; urbanization, human behaviours, population growth and mobility, interactions between virus and hosts, and vector control programs [28,29]. …”

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“…Models also showed that population growth is the main driver for dengue resurgence in Singapore [76]. These findings have significant implications for predicting future trends of the dengue epidemics given the rapid urbanisation with population growth in many dengue endemic countries.…”

“…We studied the relative contributions of putative drivers for the rise of dengue in Singapore: population growth, climate parameters and international air passenger arrivals from dengue endemic countries, from 1974 to 2011 [76]. Estimating the extent of the contribution of three factors (population growth versus weather variability versus air passenger arrivals into Singapore) on the increasing dengue incidence, we found that population growth contributed to 86% while the residual 14% was explained by increase in temperature.…”

Online platform for applying space–time scan statistics for prospectively detecting emerging hot spots of dengue fever

“…For example, Singapore has experienced increasing DF incidence over the past 40 years [1]. Similarly, Taiwan suffered from its largest outbreak in 2014 [2], and the number of cases has hit a record-high 42,856 in 2015, with the majority in Tainan and Kaohsiung, two metropolitan areas in southern Taiwan.…”