Application of the Effect of Latitude on the Starting of Hand, Foot, and Mouth Disease Epidemic on Early Warning in Dalian, Liaoning Province, China.

Hand, foot, and mouth disease (HFMD) is a common infectious gastrointestinal disease in children under the age of 5. Many studies have documented that meteorological variables, especially temperature, are associated with HFMD. Since the general climate patterns occur as latitude increases, so latitude may indirectly influence the peak time of HFMD. The objective of this study was to explore the effect of latitude on the starting of an HFMD epidemic in Dalian, which can help in the development of an early warning model of HFMD in difference latitude districts. Spearman's rank correlation coefficient was used to analyze the tendency of HFMD incidence rate over the year. A circular distribution method was used to calculate the gold standard of beginning of the HFMD epidemic. A negative binomial regression model was used to establish the early warning of the starting of the HFMD epidemic. The annualized crude incidence rate of HFMD disease in Dalian, Liaoning Province, China as a whole was 169.14 per 100,000 from 2009 to 2013.The incidence rate of HFMD varied considerably by district during the study period, but there was no significant declining or rising trend in disease incidence over the years by district of Dalian. The circular statistical analysis results showed that there was latitudinal gradient in the starting of the HFMD epidemic except for region B; the starting time of HFMD epidemic of Region A was earlier than other regions range 9 days to 18 days. The starting time of the HFMD epidemic differs from region to region with different latitudes in Dalian, Liaoning Province, China. This result can provide a scientific basis for early warning of HFMD.