title: Spatiotemporal pattern of hand-foot-mouth disease in China: an analysis of empirical orthogonal functions.
abstract: OBJECTIVE
  Hand-foot-mouth disease (HFMD) is the most common infectious disease in China. Spatial and temporal patterns of HFMD in China provide valuable information on the relationship between HFMD and the geographical environment, and help in the prediction of HFMD transmission.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Total HFMD morbidity per 10 days from May 2008 to March 2009 was recorded in 1966 counties in China. Empirical orthogonal function (EOF) analysis was used to obtain spatial and temporal patterns of HFMD.
  
  
  RESULTS
  The first five modes of HFMD morbidity explained 84.24% of the total variance. The dominant mode (first mode showing the highest variance) showed high HFMD morbidity in the western counties of Bohai Bay, the mid-south of China, the Yangtze River delta, the Pearl River delta and the areas bordering Vietnam from early May to late July 2008. The second mode showed high HFMD morbidity in the western counties of Bohai Bay, the north-east of China, north of Xinjiang and the Yangtze River delta from late May to the middle of August 2008. The third mode showed high HFMD morbidity in the Yangtze River delta, the Pearl River delta and the middle of the Huaihe River basin in early May 2008.
  
  
  CONCLUSIONS
  EOF analysis of HFMD morbidity shows the main spatiotemporal patterns and can explain variance in HFMD in China.
authors.affiliation: State Key Lab of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
authors.forename: R X
authors.initials: RX
authors.lastname: Shi
authors.affiliation: State Key Lab of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China. Electronic address: wangjf@lreis.ac.cn.
authors.forename: J F
authors.initials: JF
authors.lastname: Wang
authors.affiliation: State Key Lab of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
authors.forename: C D
authors.initials: CD
authors.lastname: Xu
authors.affiliation: Key Laboratory of Surveillance and Early Warning on Infectious Disease, Chinese Centre for Disease Control and Prevention, Beijing, China.
authors.forename: S J
authors.initials: SJ
authors.lastname: Lai
authors.affiliation: Key Laboratory of Surveillance and Early Warning on Infectious Disease, Chinese Centre for Disease Control and Prevention, Beijing, China.
authors.forename: W Z
authors.initials: WZ
authors.lastname: Yang
mesh_terms: D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D006232:Hand, Foot and Mouth Disease / Q000453:epidemiology*; D006801:Humans; D011159:Population Surveillance / Q000379:methods*; D062211:Spatio-Temporal Analysis
keywords: Empirical orthogonal function; Hand–foot–mouth disease; Spatial pattern; Temporal score