Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Shushan District, Hefei, Anhui 230032, PR China.
Hefei Center for Disease Control and Prevention, 86 Luan Road, Luyang District, Hefei, Anhui 230061, PR China.
Sci Total Environ. 2018 Jul 15;630:820-826. doi: 10.1016/j.scitotenv.2018.02.262. Epub 2018 Mar 7.
In recent years, hand, foot, and mouth disease (HFMD) has become a major public health issue in China, and its reinfection rate has been high. Numerous studies have examined the effects of meteorological factors involved in HFMD infection. However, no study has investigated the effects on HFMD reinfection. The present study analyzed the relationship between relative humidity and HFMD reinfection.
We employed a distributed lag nonlinear model to evaluate the relationship between relative humidity and childhood HFMD reinfection in Hefei, China during 2011-2016. This model controlled confounding factors, including seasonality, long-term trend, day of the week, precipitation, and mean temperature.
Childhood HFMD reinfection cases occurred mainly from April to July, and the second peak occurred from October to December. A statistically significant association was observed between relative humidity and HFMD reinfection with delayed effects. The adverse effect of high relative humidity (>75%) appeared later than those of low relative humidity (<75%). Moreover, the highest relative risk (RR 1.08, 95% CI 1.04-1.13) occurred when the relative humidity was 100% and had an 8-day lag. Given the differences between gender and age groups, the effects of extremely high relative humidity on females and those aged ≥4years were higher than those of other groups and caused the highest cumulative relative risks at lag 0-9 or 0-10days (Female: RR 2.00, 95% CI 1.23-3.26; Male: RR 1.55, 95% CI 1.04-2.30; Aged ≥4years: RR 2.31, 95% CI 1.27-4.18; Aged <4years: RR 1.51, 95% CI 1.04-2.20).
High and low relative humidity were found to cause the elevated risks of HFMD reinfection, and the highest risk was observed at extremely high relative humidity. Early warning systems should be built for the protection of susceptible populations, particularly females and children aged ≥4years.
近年来，手足口病（HFMD）已成为中国的一个重大公共卫生问题，其再感染率居高不下。已有大量研究探讨了与 HFMD 感染相关的气象因素的影响。然而，尚无研究探讨其对 HFMD 再感染的影响。本研究分析了相对湿度与 HFMD 再感染之间的关系。
我们采用分布式滞后非线性模型，评估了 2011 年至 2016 年期间中国合肥相对湿度与儿童 HFMD 再感染之间的关系。该模型控制了季节性、长期趋势、星期几、降水和平均温度等混杂因素。
HFMD 再感染病例主要发生在 4 月至 7 月，第二个高峰发生在 10 月至 12 月。相对湿度与 HFMD 再感染之间存在显著的滞后效应关联。高相对湿度（>75%）的不良影响比低相对湿度（<75%）出现得晚。此外，当相对湿度为 100%且存在 8 天滞后时，相对风险最高（RR 1.08，95%CI 1.04-1.13）。考虑到性别和年龄组的差异，极高相对湿度对女性和≥4 岁儿童的影响高于其他组，导致滞后 0-9 天或 0-10 天的累积相对风险最高（女性：RR 2.00，95%CI 1.23-3.26；男性：RR 1.55，95%CI 1.04-2.30；≥4 岁：RR 2.31，95%CI 1.27-4.18；<4 岁：RR 1.51，95%CI 1.04-2.20）。
高湿度和低湿度均会导致 HFMD 再感染风险升高，而极高湿度时风险最高。应建立早期预警系统，以保护易感人群，特别是女性和≥4 岁的儿童。
