Retrospective Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 7, 2015; 21(17): 5295-5302
Published online May 7, 2015. doi: 10.3748/wjg.v21.i17.5295
Acute gastroenteritis outbreak caused by a GII.6 norovirus
Ling-Fei Luo, Kun Qiao, Xiao-Guang Wang, Ke-Ying Ding, Hua-Ling Su, Cui-Zhen Li, Hong-Jing Yan
Ling-Fei Luo, Kun Qiao, Xiao-Guang Wang, Ke-Ying Ding, Hua-Ling Su, Cui-Zhen Li, Hong-Jing Yan, The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, China
Author contributions: Luo LF and Qiao K contributed equally to this work; Wang XG designed the research; Luo LF and Qiao K performed the research; Ding KY, Su HL, Li CZ and Yan HJ contributed reagents and analytic tools; and Wang XG analyzed the data and wrote the paper.
Ethics approval: This study was conducted according to the principles of World Medical Association Declaration of Helsinki. The study was specifically approved by Internal Review Board of the Center for Disease Control and Prevention of Shanghai Minhang District, China (Permit Number: 2013-0012).
Informed consent: All participants gave written informed consent for research use of stool samples. We also obtained written informed consent from the parents on the behalf of the minors enrolled in our study, the ethics committee specifically approved the consent procedure for the participants between 9 and 10 years of age (Permit Number: 2013-0012m).
Conflict-of-interest: The authors have declared that no conflict-of-interest exists.
Data sharing: All data are included in this report.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Xiao-Guang Wang, MD, The Center for Disease Control and Prevention of Minghang District, No. 965 Zhongyi Road, Minghang District, Shanghai 201101, China. wxg2479038@sina.com
Telephone: +86-21-54880808 Fax: +86-21-54880808
Received: October 31, 2014
Peer-review started: November 3, 2014
First decision: November 26, 2014
Revised: December 11, 2014
Accepted: January 30, 2015
Article in press: January 30, 2015
Published online: May 7, 2015
Abstract

AIM: To report an acute gastroenteritis outbreak caused by a genogroup 2 genotype 6 (GII.6) strain norovirus in Shanghai, China.

METHODS: Noroviruses are responsible for approximately half of all reported gastroenteritis outbreaks in many countries. Genogroup 2 genotype 4 strains are the most prevalent. Rare outbreaks caused by GII.6 strains have been reported. An acute gastroenteritis outbreak occurred in an elementary school in Shanghai in December of 2013. Field and molecular epidemiologic investigations were conducted.

RESULTS: The outbreak was limited to one class in an elementary school located in southwest Shanghai. The age of the students ranged from 9 to 10 years. The first case emerged on December 10, 2013, and the last case emerged on December 14, 2013. The cases peaked on December 11, 2013, with 21 new cases. Of 45 students in the class, 32 were affected. The main symptom was gastroenteritis, and 15.6% (5/32) of the cases exhibited a fever. A field epidemiologic investigation showed the pathogen may have been transmitted to the elementary school from employees in a delicatessen via the first case student, who had eaten food from the delicatessen one day before the gastroenteritis episodes began. A molecular epidemiologic investigation identified the cause of the gastroenteritis as norovirus strain GII.6; the viral sequence of the student cases showed 100% homology with that of the shop employees. Genetic relatedness analyses showed that the new viral strain is closely related to previously reported GII.6 sequences, especially to a strain reported in Japan.

CONCLUSION: This is the first report to show that norovirus strain GII.6 can cause a gastroenteritis outbreak. Thus, the prevalence of GII.6 noroviruses requires attention.

Keywords: Genogroup 2 genotype 6 genogroup, Genetic relatedness analyses, Gastroenteritis, Noroviruses, Outbreak

Core tip: Noroviruses are responsible for approximately half of all reported gastroenteritis outbreaks in many countries. Rare outbreaks caused by genogroup 2 genotype 6 (GII.6) strains have been reported. An acute gastroenteritis outbreak occurred in an elementary school in Shanghai in December of 2013. Molecular epidemiologic investigations showed that the gastroenteritis outbreak was caused by norovirus strain GII.6 infection. Thus, the prevalence of GII.6 noroviruses requires attention.