Epidemiological characteristics of acute gastroenteritis outbreaks caused by norovirus in China, 2000-2013

Objective To understand the epidemiological characteristics of acute gastroenteritis outbreaks caused by norovirus in China and provide evidence for the development of effective control measures. Methods A literature retrieval was conducted by using the database of CNKI, Wan Fang, VIP and others in China. The key words norovirus, norwalk-like virus and outbreak, investigate were used. Results A total of 52 papers about 72 norovirus infection outbreaks, involving 11 778 patients, were collected according to the inclusion and exclusion criteria. Averagely 164 cases occurred in each outbreak and the average epidemic duration was 8.57 days. The first 3 provinces in reporting outbreak number were Guangdong (28, 38.89%), Zhejiang (18, 25.00%) and Guangxi (6, 8.33%). The outbreaks occurred mainly in schools and kindergartens, accounting for 73.61%, including 25 in high schools, 17 in kindergartens and primary schools and 11 in colleges, followed by old people home/medical institutions, accounting for 13.89%.The main transmission routes included water drinking (27, 37.50%), close contact (24, 33.33%), food eating (17, 23.61%). The place and transmission route specific differences in the incidence were significant (2=48.899, P=0.000). Barrelled water drinking caused 48.15% of the water borne outbreaks. Twenty four outbreaks were caused by genotype GⅡ, accounting for 72.73%, 6 were caused by genotype GⅠ, accounting for 18.18%. Conclusion Norovirus outbreak was prone to occur in schools and kindergartens, to which close attention should be paid. It is suggested to strengthen the management of the place at high risk, improve water quality surveillance and increase the pathogen detection level.