[Epidemiological features of hand, foot and mouth disease in China, 2008 - 2009].

Objective: To clarify the seasonal and geographical difference and pathogen patterns so as to provide reference of prevention and control of the disease through analyzing the epidemic characteristics of reported hand-foot-mouth disease (HFMD) cases in China, 2008 - 2009.

Methods: We analysed the epidemiological data of HFMD from the Chinese national notifiable infectious diseases reporting system in 2008 and 2009.

Results: There were 488 955 and 1 155 525 reported HFMD cases in 2008 and 2009, in China, of which 1165 and 13 810 were severe and 126 and 353 were fatal, respectively. The notification rates were 50.09/10 million, 68.47/10 million and 59.04/10 million in high, medium and low latitudes areas, respectively. The epidemic periods in Medium and Low latitude were from 12 to 24 weeks in 2009, and in high latitude it was from 23 to 35 weeks. HFMD cases were concentrated mainly in 5 year-old or even younger children, accounted for 92.23% of the total cases. The incidence rate of two years old appeared to be the highest. The features of severe and death case concentrated in lower age groups were more evident, and the proportion of severe case and case fatality rate under 1 years old was higher than that in other age groups. We also noticed that with the increasing of age, the proportion of severe case and case fatality rate had a decreasing trend. There was a difference between the pathogens seen. The relative risk (RR) for an human enterovirus 71 (HEV71) isolate was higher among severe case than in common cases (RR = 1.82), whereas the RR for an EV71 isolate was higher among the death cases than in common cases (RR = 2.11). There was seasonal variation of pathogen composition. There were 477 clusters of cases from 2008 to 2009, of which 389 found in preschools, 47 in rural villages, outbreaks of clusters were mainly from April to July.

Conclusion: The HFMD epidemics was increasing in 2009. The epidemic of HFMD in different latitudes area and seasons was different. Children of five year old or under were the major population groups at risk, of HFMD. The younger ones had higher risk of becoming severe and death cases. HEV71 and coxsackievirus A16 were both the major etiologic agents of HFMD. The preschool and rural villages were the main settings of clusters of cases.