title: Quantifying the adverse effect of excessive heat on children: An elevated risk of hand, foot and mouth disease in hot days.
abstract: BACKGROUND
  Hand, foot and mouth disease (HFMD) is a common childhood infection and has become a major public health issue in China. Considerable research has focused on the role of meteorological factors such as temperature and relative humidity in HFMD development. However, no studies have specifically quantified the impact of another major environmental agent, excessive heat, on HFMD. The current study was designed to help address this research gap.
  
  
  METHODS
  Case-based HFMD surveillance data and daily meteorological data collected between 2010 and 2012 was obtained from China CDC and the National Meteorological Information Center, respectively. Distributed lag nonlinear models were applied to assess the impact of excessive heat on HFMD and its variability across social-economic status and age groups.
  
  
  RESULTS
  After controlling the effects of several potential confounders, the commonly hot days were found to positively affect the HFMD burdens with the relative risk (RR) peaking at around 6 days of lag. The RR of HFMD in the Pearl-River Delta Region was generally higher and persisted longer than that in the remaining developing areas. Regarding the inter-age group discrepancy, children aged 3-6 years old had the highest risk of HFMD under conditions of excessive heat whereas those greater than 6 years old had the lowest. The lag structure of the impact of the extremely hot days was quite similar to that of the commonly hot days, although the relative effect of these two kinds of conditions of excessive heat might vary across regions.
  
  
  CONCLUSIONS
  This study indicated significantly facilitating effects of excessive heat on HFMD especially among those aged 3-6 and from developed areas. Results from the current study were particularly practical and important for developing area-and-age-targeted control programs in the context of climate change and urbanization.
authors.affiliation: Department of Medical Statistics and Epidemiology, Health Information Research Center, Guangdong Key Laboratory of Medicine, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, Guangdong Province, China. Electronic address: zhangwj35@mail2.sysu.edu.cn.
authors.forename: Wangjian
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Medical Statistics and Epidemiology, Health Information Research Center, Guangdong Key Laboratory of Medicine, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, Guangdong Province, China. Electronic address: duzhch3@mail2.sysu.edu.cn.
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Du
authors.affiliation: Department of Medical Statistics and Epidemiology, Health Information Research Center, Guangdong Key Laboratory of Medicine, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, Guangdong Province, China. Electronic address: zhdingm@mail.sysu.edu.cn.
authors.forename: Dingmei
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Chinese Center for Disease Control and Prevention, Beijing 102206, China. Electronic address: shicheng_yu@hotmail.com.
authors.forename: Shicheng
authors.initials: S
authors.lastname: Yu
authors.affiliation: Department of Medical Statistics and Epidemiology, Health Information Research Center, Guangdong Key Laboratory of Medicine, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, Guangdong Province, China. Electronic address: haoyt@mail.sysu.edu.cn.
authors.forename: Yuantao
authors.initials: Y
authors.lastname: Hao
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D057231:Climate Change; D005260:Female; D006232:Hand, Foot and Mouth Disease / Q000453:epidemiology*; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007223:Infant; D008297:Male; D008685:Meteorological Concepts; D011634:Public Health; D012307:Risk Factors
keywords: Distributed lag nonlinear model; Excessive heat; HFMD; Humidex; Variability