Epidemiology and etiology of hand, foot and mouth disease outbreaks in Changning,2011-2015

Objective To understand the epidemiological and etiological characteristics of hand, foot and mouth disease (HFMD) outbreaks in Changning district, Shanghai, and provide scientific evidence for HFMD prevention and control. Methods The incidence data of HFMD epidemic from 2011 to 2015 in Changning were collected for a descriptive epidemiological analysis to understand the distribution and etiological characteristics of the epidemics. Results From January 2011 to December 2015, a total of 227 HFMD outbreaks were reported in Changning, involving 839 cases, accounting for 24.47% of total reported HFMD disease cases (839/3 429). The annual incidence peak of HFMD occurred during March-June (51.10%, 116/227). Up to 70.93% (161/227) of outbreaks occurred in child care settings. Totally 37 outbreaks (16.30%) were reported within 1 day. And the durations of outbreaks ranged from 1 to 18 days (median: 4 days), the inter-quartilerange was 2-6 days. The duration of the outbreak was positively correlated with the time to take response measures (r=0.318, P=0.001). The incidence peak caused by EV71 occurred during May-June, earlier than the peak of Cox A16 and other enteroviruses (during June-July). EV71 was the major pathogen, accounting for 40.94% (70/171); the pathogens detected differed in different quarters. The difference was significant (2 =13.799,P=0.032). Conclusion Early response to HFMD outbreak could effectively reduce the epidemic duration. The reporting management should be strengthened. HFMD pathogen differed in different season in Changning, and more attention should be paid to the clustering of HFMD cases caused by EV71 during May-June, especially the severe cases caused by EV71. The surveillance for HFMD pathogens, timely reporting and response should be strengthened to prevent and control the epidemics of HFMD.