Analysis on seasonal distribution characteristics of hand foot and mouth disease in Qinghai Province based on the concentration and circular distribution method

Objective To analyze the seasonal distribution of incidence of hand foot and mouth disease (HFMD) in Qinghai Province, so as to provide the scientific basis evidence for the establishment of prevention and controlling strategies of HFMD. Methods The HFMD incident cases who lived in Qinghai Province were collected from the China Information System for Disease Control and Prevention by month during 2012-2016. We used the concentration and circular distribution method to depict the characteristics of HFMD incidence in Qinghai Province. Results There was a significant seasonal periodicity in the incidence of HFMD in Qinghai Province (M=0.613), and the peak of incidence was generally happened from May to August every year (r=0.610,a=181.322°, s=57.004°). The results from Watson-Williams analysis showed that the average angle of peak time was changed every year (F=31.492, P<0.001), which indicated a changeable peak time of HFMD incidence. Conclusions We found a statistically significant seasonal periodicity in the incidence of HFMD in Qinghai Province. Therefore, the prevention and control strategies should be carried out before the high-risk season as soon as possible, which would be efficiently reduce the occurrence of severe cases and prevent the possibility of epidemic outbreak.