title: Spatio-temporal clustering of hand, foot, and mouth disease at the county level in Guangxi, China.
abstract: BACKGROUND
  Amid numerous outbreaks of hand, foot and mouth disease (HFMD) in Asia over the past decade, studies on spatio-temporal clustering are limited. Without this information the distribution of severe cases assumed to be sporadic. We analyzed surveillance data with onset dates between 1 May 2008 to 31 October 2013 with the aim to document the spatio-temporal clustering of HFMD cases and severe cases at the county level.
  
  
  METHODS
  Purely temporal and purely spatial descriptive analyses were done. These were followed by a space-time scan statistic for the whole study period and by year to detect the high risk clusters based on a discrete Poisson model.
  
  
  RESULTS
  The annual incidence rate of HFMD in Guangxi increased whereas the severe cases peaked in 2010 and 2012. EV71 and CoxA16 were alternating viruses. Both HFMD cases and severe cases had a seasonal peak in April to July. The spatio-temporal cluster of HFMD cases were mainly detected in the northeastern, central and southwestern regions, among which three clusters were observed in Nanning, Liuzhou, Guilin city and their neighbouring areas lasting from 1.2 to 2.5 years. The clusters of severe cases were less consistent in location and included around 40-70% of all severe cases in each year.
  
  
  CONCLUSIONS
  Both HFMD cases and severe cases occur in spatio-temporal clusters. The continuous epidemic in Nanning, Liuzhou, Guilin cities and their neighbouring areas and the clusters of severe cases indicate the need for further intensive surveillance.
authors: Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control, Nanning, Guangxi, China ; Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, HatYai, Songkla, Thailand ; International Field Epidemiology Training Program (IFETP), Bureau of Epidemiology, Ministry of Public Health, Bangkok, Thailand.
authors: Yi-hong
authors: YH
authors: Xie
authors: Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, HatYai, Songkla, Thailand.
authors: Virasakdi
authors: V
authors: Chongsuvivatwong
authors: Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control, Nanning, Guangxi, China.
authors: Zhenzhu
authors: Z
authors: Tang
authors: Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, HatYai, Songkla, Thailand.
authors: Edward B
authors: EB
authors: McNeil
authors: Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control, Nanning, Guangxi, China.
authors: Yi
authors: Y
authors: Tan
mesh_terms: D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D005260:Female; D005528:Foot / Q000821:virology; D006225:Hand / Q000821:virology; D006232:Hand, Foot and Mouth Disease / Q000453:epidemiology*; D006801:Humans; D008297:Male; D009055:Mouth / Q000821:virology; D012621:Seasons; D012720:Severity of Illness Index