Abstract
BackgroundNumerous studies have demonstrated the potential association between rainfall and hand, foot and mouth disease (HFMD), but the results are inconsistent. This study aimed to quantify the relationship between rainfall and HFMD based on a multicity study and explore the potential sources of spatial heterogeneity.MethodsWe retrieved the daily counts of childhood HFMD and the meteorological variables of the 143 cities in mainland China between 2009 and 2014. A common time series regression model was applied to quantify the association between rainfall and HFMD for each of the 143 cities. Then, we adopted the meta-regression model to pool the city-specific estimates and explore the sources of heterogeneity by incorporating city-specific characteristics.ResultsThe overall pooled estimation suggested a nonlinear exposure-response relationship between rainfall and HFMD. Once rainfall exceeded 15 mm, the HFMD risk stopped increasing linearly and began to plateau with the excessive risk ratio (ERR) peaking at 21 mm of rainfall (ERR = 3.46, 95% CI: 2.05, 4.88). We also found significant heterogeneity in the rainfall-HFMD relationships (I2 = 52.75%, P < 0.001). By incorporating the city-specific characteristics into the meta-regression model, temperature and student density can explain a substantial proportion of spatial heterogeneity with I2 statistics that decreased by 5.29 and 6.80% at most, respectively.ConclusionsOur findings verified the nonlinear association between rainfall and HFMD. The rainfall-HFMD relationship also varies depending on locations. Therefore, the estimation of the rain-HFMD relationship of one location should not be generalized to another location.
Highlights
Numerous studies have demonstrated the potential association between rainfall and hand, foot and mouth disease (HFMD), but the results are inconsistent
From 2009 to 2014, by including 143 cities in mainland China, we retrieved a total of 3,200,157 HFMD clinical cases in children under 12 years old
Given that similar spatial-temporal patterns were observed between rainfall and HFMD, it was reasonable to assume that rainfall might be an environmental driver of the HFMD epidemic
Summary
Numerous studies have demonstrated the potential association between rainfall and hand, foot and mouth disease (HFMD), but the results are inconsistent. Foot and mouth disease (HFMD) is an acute highly contagious viral infection caused by enteroviruses and predominantly affects children under 5 years of age [1, 2]. In mainland China, HFMD is the leading childhood infection among all notifiable diseases and responsible for millions of clinical cases [8] and greater than 75,000 age-weighted disability adjusted life years (DALYs) annually [9]. Multiple studies suggested that the water environment plays a crucial role in the survival of enterovirus (i.e., the pathogen of HFMD), thereby potentially affecting the transmission of HFMD. As the main source of natural water environments, rainfall was considered as an important driving factor of HFMD epidemics
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