Daily Mean Temperature and HFMD: Risk Assessment and Attributable Fraction Identification in Ningbo China

Abstract

Background: Hand, foot and mouth disease (HFMD) remains a significant public health issue, especially in developing countries. Many studies have reported the association between environmental temperature and HFMD. However, the results are highly heterogeneous in different regions. In addition, there are few studies on the attributable risk of HFMD.Objectives: The study aimed to assess the association between temperature and HFMD incidence and to evaluate the attributable burden of HFMD in Ningbo China.Methods: The research used daily incidence of HFMD from 2014 to 2017 and distributed lag non-linear model (DLNM) to investigate the effects of daily mean temperature (Tmean) on HFMD incidence from lag 0 to 30 days, after controlling potential confounders. The lag effects and cumulative relative risk (CRR) were analyzed. Attributable fraction (AF) of HFMD incidence due to temperature was calculated. Stratified analysis by age and gender were also conducted.Results: The Significant associations between Tmean and HFMD incidence were observed in Ningbo for lag 0-30. Two peaks were observed at both low (5°C -11°C ) and high (16°C -29°C ) temperature scales. For low temperature scale, the highest CRR was 2.22% (95% CI: 1.61-3.07) at 7°C on lag 0-30. For high temperature scale, the highest CRR was 3.54% (95% CI: 2.58-4.88) at 24°C on lag 0-30. The AF of low and high temperature was 5.23% (95% CI: 3.10-7.14) and 39.55% (95% CI: 30.91-45.51), respectively. There was no significant difference between gender- and age-specific AFs, even though the school-age and female children had slightly higher AF values.Conclusions: The result indicates that both high and low temperatures were associated with daily incidence of HFMD, and more burdens were caused by heat in Ningbo.

The effect of daily mean temperature on hand, foot and mouth disease and the source of regional heterogeneity in Chongqing, China, 2010–2019

“…There was evidence that women were more vulnerable to cold temperatures than men [39]. The age-specific results showed that children aged 0-1 were more vulnerable to warm temperature and the CRR was the highest, which was consistent with other studies [9,15]. It has been reported that maternal antibody levels to EV71 declined one month after birth, and thus the lack of immunity increased the susceptibility of children under 1 year of age to temperature [40].…”

“…This may be due to the fact that children aged 3-6 were more likely to gather in a closed environment in cold weather (such as kindergartens), and worse indoor ventilation in cold days might facilitate the transmission of HFMD [41]. However, cold temperature was a protective factor associated with HFMD for scattered children, possibly because they were more likely to stay at home and reduce outdoor activities in cold weather, thus they had less opportunities to contact with each other and be exposed to contaminants [15].…”

“…For example, some studies in Japan [11], Taiwan [12], and mainland China [13] showed an increased risk of HFMD at moderately high temperatures but a decreased risk at extremely hot temperatures, approximating an inverted V-shape, while a study in Singapore [14] showed a threshold and J-shaped relationship between temperature and HFMD. Besides, some studies in eastern China found that the exposure-response relationship between temperature and HFMD was non-linear with an approximate M-shape [15,16]. The above studies were mainly focused on a single city or region, and the differences in the results might be attributed to the climatic conditions, socio-economic factors and demographic characteristics of different regions [17].…”