Chen Tzu Tung, Kim Yoonhee, Ljungqvist Fredrik Charpentier, Jarsjö Jerker, Hesson Jenny C, Linderholm Hans W
Regional Climate Group, Department of Earth Sciences, University of Gothenburg, Sweden.
Department of Global Environmental Health, Graduate School of Medicine, University of Tokyo, Japan.
Scand J Public Health. 2025 Mar;53(2):162-171. doi: 10.1177/14034948251320865. Epub 2025 Mar 13.
Until the late 19th century, malaria was endemic in most of Europe including in the Nordic countries. In Denmark, Finland, and Sweden, the fluctuations in malaria cases and malaria-attributed deaths are known to have been associated with weather conditions, in particular with mean summer temperature variations. However, to what extent other environmental factors could have increased or decreased the risk of malaria has not previously been evaluated using historical records.
In this study, we illustrate the non-linear association between different environmental variables (temperature, precipitation, and sea-level variations) and symptom-based malaria (case and death) data, using the quasi-Poisson distributed lag non-linear model. The robustness of the model results was examined through sensitivity analysis.
The modeling results showed that the risk associated with temperature increased by ∼25% in Denmark and by ∼67% in Sweden and Finland, with a mean summer temperature increase from 16°C to 18°C, was highest at 1-2 lagged years. Furthermore, average precipitation could have a noticeable effect on the malaria risk in Sweden and Finland, but this effect was not observed in Denmark. Environmental perturbations associated with extreme sea levels (>99.7th percentile or <0.1th percentile), including subsequent saltwater intrusion, could lead to increasing malaria risk in low-lying coastal areas.
The historical evidence and modeling results suggest that specific weather conditions and extreme events have substantial impacts on malaria in temperate regions.
直到19世纪末，疟疾在包括北欧国家在内的欧洲大部分地区都呈地方流行状态。在丹麦、芬兰和瑞典，已知疟疾病例和疟疾所致死亡的波动与天气状况有关，特别是与夏季平均气温变化有关。然而，此前尚未利用历史记录评估其他环境因素在多大程度上可能增加或降低疟疾风险。
在本研究中，我们使用准泊松分布滞后非线性模型说明了不同环境变量（温度、降水和海平面变化）与基于症状的疟疾（病例和死亡）数据之间的非线性关联。通过敏感性分析检验了模型结果的稳健性。
建模结果表明，随着夏季平均气温从16°C升高到18°C，丹麦与温度相关的风险增加约25%，瑞典和芬兰增加约67%，在滞后1 - 2年时风险最高。此外，平均降水量可能对瑞典和芬兰的疟疾风险有显著影响，但在丹麦未观察到这种影响。与极端海平面（>第99.7百分位数或<第0.1百分位数）相关的环境扰动，包括随后的海水入侵，可能导致低洼沿海地区的疟疾风险增加。
历史证据和建模结果表明，特定的天气状况和极端事件对温带地区的疟疾有重大影响。
