An investigation on a food-borne outbreak caused by norovirus infection

Zhiyin XU; Long Chen; Zhaowen Zhang; Lifang Zhao; Jingjing Zhang; Xiaoning Zhu; Xiaoguang Wang; Mei Zeng; Jing Lyu; Hao Pan

Return

An investigation on a food-borne outbreak caused by norovirus infection

VernacularTitle:一起食源性诺如病毒感染性腹泻疫情的调查
Author: Zhiyin XU ¹ ; Long CHEN ¹ ; Zhaowen ZHANG ¹ ; Lifang ZHAO ¹ ; Jingjing ZHANG ¹ ; Xiaoning ZHU ¹ ; Xiaoguang WANG ¹ ; Mei ZENG ² ; Jing LYU ¹ ; Hao PAN ³
Author Information

1. Minhang District Center of Disease Control and Prevention,Shanghai 201101,China
2. Children’s Hospital of Fudan University, Shanghai 201102, China
3. Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China
Publication Type:Journal Article
Keywords: kindergarten; norovirus; Aeromonas hydrophila; diarrhea; food-borne
From: Shanghai Journal of Preventive Medicine 2022;34(4):331-334
CountryChina
Language:Chinese
Abstract: ObjectiveTo determine the epidemiological characteristics and risk factors of a norovirus GII.17 outbreak in Minhang District of Shanghai in 2018， and provide evidence for prevention and control measures of norovirus infection. MethodsDescriptive epidemiological analysis was performed. In addition， a retrospective cohort study was conducted to determine the risk factors. ResultsFrom May 30^th to June 1^st of 2018， a total of 132 cases （126 clinical cases and 6 confirmed cases） were documented，with an attack rate of 29.20%（132/452）.All cases were children in a kindergarten， with the average age of 5 years and 43.9% being male. The cases were reported in all the classes， with no clustering by class or floor．The epidemic curve was characterized by a point source exposure， which was estimated to be probably between 7 AM on May 30^thand 0：30 AM on May 31^st. The retrospective cohort study showed that the attack rate significantly differed between the children who had taken and did not take the school lunch （RR=∞） on May 30^th，and those who had taken and did not take seafood noodles （RR=4.11， 95%CI：1.09-15.55）（P<0.05）. Among a total of 73 specimens， six specimens collected in child cases and one specimen in an asymptomatic chef tested positive for GII.17 type of norovirus. In addition， one retained food specimen of seafood noodles was positive for Aeromonas hydrophila. Viral shedding in the asymptomatic chef remained over 30 days. ConclusionThe outbreak was caused by seafood noodles contaminated by norovirus. It warrants enhancement in the regulation of food safety in canteens and regular examination of norovirus infection in catering industry employees.