An epidemiological analysis of the Beijing 2008 Hand-Foot-Mouth epidemic

This paper presents an empirical analysis of the epidemiological data concerning the 18445 HFMD-infected cases in Beijing in 2008. The main findings are as follows. (i) Seasonal variations in incidence were observed, with a peak observed during the summer season, especially in May. Male patients outnumber female patients by 1.57:1. (ii) Most cases occurred in children 4 years old or younger. Outperforming Weibull distribution and Gamma distribution as to model fitness when analyzing patient ages, log-normal distribution indicates that the estimated mean age is 3.4 years. (iii) The age distribution seems to indicate cyclic peaks with roughly one-year intervals. (iv) Correlation analyses (ρ = 0.9864) show that time of birth in different months has an impact on the chance of being infected by HFMD. Birth month seems to present a high risk factor on infants and young children. (v) The morbidity rate is 132.7/100000 during the HFMD epidemic in Beijing in 2008. The morbidity map shows that the risks of HFMD infection in areas close to the city center and suburbans are much lower than those in the urban-rural transition zones. Spatial risks inferred from the morbidity map demonstrate a clear circular pattern. (vi) The prevention and control measures taken by the public health departments seem to be effective during the summer season, resulting in the early ending of the epidemic (one month earlier than the natural season) and reduced outbreak size.