[Epidemiological analysis on bud-events of Norovirus-associated infectious diarrhea in Shanghai, 2018].

Objective: To analyze the epidemiological characteristics related to Norovirus-associated infectious diarrhea bud events in Shanghai, and to discuss the value of bud events surveillance, so as to help Norovirus-associated infectious diarrhea control, prevention and to improve the surveillance system on bud events. Methods: Data related to 142 Norovirus-associated infectious diarrhea bud events were gathered from 16 districts of Shanghai areas in 2018 and were analyzed. Results: There were 2 peaks, April and November for 142 Norovirus-associated infectious diarrhea bud events reported in 2018. 98.59% (140/142) of the bud events occurred in schools and kindergartens. 80.28% (114/142) of the bud events would involve 6-19 cases per each event. The median time duration between the onset date of the first case and the reporting date of the event was 2 days and the median event duration was 7 days. The bud event scale and regional incidence of bud events as well as the reporting timelines were influential factors on the duration of the bud events. Conclusions: Two peaks, spring and winter bud events of the Norovirus-associated infectious diarrhea were seen in Shanghai in 2018. Schools and kindergartens were to be prioritized locations for control and prevention of Norovirus-associated infectious diarrhea bud events. Surveillance system was proved to have contributed to the early detection, reporting and control of bud events.