Climate variability and dengue in Singapore, Fiji, and Hong Kong: small bite, big threat

Abstract

Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).Dengue is highly sensitive to climatic conditions, especially temperature, rainfall, and relative humidity. Potential changes in climate may lead to an increased climatic suitability for transmission and an expansion of the geographical regions at risk. 1 Studies have shown annual minimum temperature as a key regulating climate parameter for dengue, and an increase in dengue transmission due to climate warming. The dengue virus is transmitted through the bites of infective female Aedes mosquitoes. When ambient temperatures were raised from 24 to 32°C, female Aedes mosquitoes display accelerated breeding and maturation cycles, shorter reproductive cycles, and double the feeding rate. In other words, they become infective earlier and bite more frequently. Dengue transmissions are attributable to urbanization with population growth, globalization, lack of effective control, and other human factors. 2 Rainfall is another predictor of epidemic risk that is important because it contributes to an increase in breeding sites.Dengue is associated with morbidity, mortality, and significant economic cost. A country' s dengue transmission is associated with risk factors unique to that country, as the effect of climate on Aedes aegypti may vary within a region, due in part to social factors that interact with climate to influence vector dynamics. 3 Aedes aegypti lives in urban habitats and breeds primarily in man-made containers that collect water. These prolific sources open a window of opportunity for dengue to proliferate. Aedes albopictus is a secondary dengue vector that is highly adaptive and can survive in cooler temperatures.Smaller nations such as Singapore, Fiji, and Hong Kong are already facing climate change and are coming to terms with its impact on dengue transmission. These nations can expect more extreme weather conditions, a reminder to raise awareness of climate change and its impact on dengue transmission.In Singapore, the impact of climate change has been observed in the rate of warming over a period of six decades to be more than double the global average of 0.12°C over the same period. 4 With the change, there is a projected rise in mean temperature by up to 4.6°C towards the end of the century and a mean sea level rise by up to about 1 m by 2100. Responding to these changes, the Singapore government has started initiatives in generating awareness about climate change by designating 2018 as the Year of Climate Action. 5 Singapore is a small and highly urbanized tropical island city-state with hot and humid weather. It houses two vectors of dengue, A. aegypti and A. a...

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