Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China.
Institute of Population Health Sciences, National Health Research Institutes, Miaoli County, Taiwan.
Sci Rep. 2020 Mar 9;10(1):4297. doi: 10.1038/s41598-020-60309-7.
In recent years, dengue has been rapidly spreading and growing in the tropics and subtropics. Located in southern China, Hong Kong's subtropical monsoon climate may favour dengue vector populations and increase the chance of disease transmissions during the rainy summer season. An increase in local dengue incidence has been observed in Hong Kong ever since the first case in 2002, with an outbreak reaching historically high case numbers in 2018. However, the effects of seasonal climate variability on recent outbreaks are unknown. As the local cases were found to be spatially clustered, we developed a Poisson generalized linear mixed model using pre-summer monthly total rainfall and mean temperature to predict annual dengue incidence (the majority of local cases occur during or after the summer months), over the period 2002-2018 in three pre-defined areas of Hong Kong. Using leave-one-out cross-validation, 5 out of 6 observations of area-specific outbreaks during the major outbreak years 2002 and 2018 were able to be predicted. 42 out of a total of 51 observations (82.4%) were within the 95% confidence interval of the annual incidence predicted by our model. Our study found that the rainfall before and during the East Asian monsoon (pre-summer) rainy season is negatively correlated with the annual incidence in Hong Kong while the temperature is positively correlated. Hence, as mosquito control measures in Hong Kong are intensified mainly when heavy rainfalls occur during or close to summer, our study suggests that a lower-than-average intensity of pre-summer rainfall should also be taken into account as an indicator of increased dengue risk.
近年来，登革热在热带和亚热带地区迅速传播和蔓延。中国香港地处亚热带季风气候区，这种气候可能有利于登革热媒介种群的繁衍，并增加夏季雨季期间疾病传播的机会。自 2002 年首例病例以来，香港的本地登革热发病率一直在上升，2018 年的疫情达到了历史最高水平。然而，季节性气候变异性对最近疫情的影响尚不清楚。由于当地病例呈空间聚集性，我们使用 2002-2018 年香港三个指定区域夏季前每月总降雨量和平均温度的泊松广义线性混合模型来预测年度登革热发病率（大多数本地病例发生在夏季或夏季之后）。通过留一法交叉验证，在 2002 年和 2018 年主要疫情年份的 6 次观测中，有 5 次能够预测到区域特定疫情的发生。在总共 51 次观测中，有 42 次（82.4%）在我们模型预测的年度发病率的 95%置信区间内。我们的研究发现，东亚季风（夏前）雨季前和期间的降雨量与香港的年度发病率呈负相关，而温度则呈正相关。因此，由于香港的蚊虫控制措施主要在夏季期间或临近夏季发生大雨时加强，我们的研究表明，夏季前降雨量低于平均水平也应被视为登革热风险增加的一个指标。
