Environmental Health Institute, National Environment Agency, 40 Scotts Road, Environment Building, #13-00, Singapore 228231, Singapore.
Environmental Health Institute, National Environment Agency, 40 Scotts Road, Environment Building, #13-00, Singapore 228231, Singapore; Pre-hospital & Emergency Research Centre, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore.
Sci Total Environ. 2021 Jun 25;775:145117. doi: 10.1016/j.scitotenv.2021.145117. Epub 2021 Feb 9.
Global incidence of dengue has surged rapidly over the past decade. Each year, an estimated 390 million infections occur worldwide, with Asia-Pacific countries bearing about three-quarters of the global dengue disease burden. Global warming may influence the pattern of dengue transmission. While previous studies have shown that extremely high temperatures can impede the development of the Aedes mosquito, the effect of such extreme heat over a sustained period, also known as heatwaves, has not been investigated in a tropical climate setting.
We examined the short-term relationships between maximum ambient temperature and heatwaves and reported dengue infections in Singapore, via ecological time series analysis, using data from 2009 to 2018.
We studied the effect of two measures of extreme heat - (i) heatwaves and (ii) maximum ambient temperature. We used a negative binomial regression, coupled with a distributed lag nonlinear model, to examine the immediate and lagged associations of extreme temperature on dengue infections, on a weekly timescale. We adjusted for long-term trend, seasonality, rainfall and absolute humidity, public holidays and autocorrelation.
We observed an overall inhibitive effect of heatwaves on the risk of dengue infections, and a parabolic relationship between maximum temperature and dengue infections. A 1 °C increase in maximum temperature from 31 °C was associated with a 13.1% (Relative Risk (RR): 0.868, 95% CI: 0.798, 0.946) reduction in the cumulative risk of dengue infections over six weeks. Weeks with 3 heatwave days were associated with a 28.3% (RR: 0.717, 95% CI: 0.608, 0.845) overall reduction compared to weeks with no heatwave days. Adopting different heatwaves specifications did not substantially alter our estimates.
Extreme heat was associated with decreased dengue incidence. Findings from this study highlight the importance of understanding the temperature dependency of vector-borne diseases in resource planning for an anticipated climate change scenario.
在过去的十年中，全球登革热发病率迅速上升。据估计，每年全球有 3.9 亿例感染，亚太国家承担了全球约四分之三的登革热疾病负担。全球变暖可能会影响登革热的传播模式。虽然之前的研究表明，极高的温度会阻碍埃及伊蚊的发育，但在热带气候环境中，这种持续的极端高温（也称为热浪）对其的影响尚未得到研究。
我们通过生态时间序列分析，利用 2009 年至 2018 年的数据，研究了新加坡最高环境温度和热浪与报告登革热感染之间的短期关系。
我们研究了两种极端高温措施（i）热浪和（ii）最高环境温度的影响。我们使用负二项回归，结合分布式滞后非线性模型，每周一次检查极端温度对登革热感染的即时和滞后关联。我们调整了长期趋势、季节性、降雨量和绝对湿度、公共假期和自相关。
我们观察到热浪对登革热感染风险的总体抑制作用，以及最高温度与登革热感染之间的抛物线关系。最高温度从 31°C 增加 1°C，与六周内登革热感染累积风险降低 13.1%（相对风险（RR）：0.868，95%置信区间：0.798，0.946）相关。与没有热浪日的周相比，有 3 个热浪日的周总体上降低了 28.3%（RR：0.717，95%置信区间：0.608，0.845）。采用不同的热浪规格并没有实质性地改变我们的估计。
极端高温与登革热发病率下降有关。本研究的结果强调了在预期气候变化情景下，了解病媒传播疾病的温度依赖性对资源规划的重要性。
