Secretor Status is Associated with Susceptibility to Disease in a Large GII.6 Norovirus Foodborne Outbreak

Sumit Sharma,Beatrice Carlsson,Johan Nordgren,Ronnie Eriksson,Magnus Simonsson,Marie Hagbom,Joanna Nederby Öhd,Micael Widerström,Mona Insulander

doi:10.1007/s12560-019-09410-3

Abstract

Norovirus is commonly associated with food and waterborne outbreaks. Genetic susceptibility to norovirus is largely dependent on presence of histo-blood group antigens (HBGA), specifically ABO, secretor, and Lewis phenotypes. The aim of the study was to determine the association between HBGAs to norovirus susceptibility during a large norovirus foodborne outbreak linked to genotype GII.6 in an office-based company in Stockholm, Sweden, 2015. A two-episode outbreak with symptoms of diarrhea and vomiting occurred in 2015. An online questionnaire was sent to all 1109 employees that had worked during the first outbreak episode. Food and water samples were collected from in-house restaurant and tested for bacterial and viral pathogens. In addition, fecal samples were collected from 8 employees that had diarrhea. To investigate genetic susceptibility during the outbreak, 98 saliva samples were analyzed for ABO, secretor, and Lewis phenotypes using ELISA. A total of 542 of 1109 (49%) employees reported gastrointestinal symptoms. All 8 fecal samples tested positive for GII norovirus, which was also detected in coleslaw collected from the in-house restaurant. Eating at the in-house restaurant was significantly associated with risk of symptom development. Nucleotide sequencing was successful for 5/8 fecal samples and all belonged to the GII.6 genotype. HBGA characterization showed a strong secretor association to norovirus-related symptoms (P = 0.014). No association between norovirus disease and ABO phenotypes was observed. The result of this study shows that non-secretors were significantly less likely to report symptoms in a large foodborne outbreak linked to the emerging GII.6 norovirus strain.

Highlights

Norovirus is the most common cause of viral gastroenteritis in humans and is associated with 18% of diarrheal diseases and 200,000 deaths annually worldwide, mostly among children in developing countries (Lopman et al 2016)
A large foodborne norovirus outbreak was reported in Sweden that occurred in two episodes during a three-week period in 2015 in a large office-based company in Stockholm
All employees that had worked at the office during the first outbreak episode (n = 1109) answered the online questionnaire

Summary

Introduction

Norovirus is the most common cause of viral gastroenteritis in humans and is associated with 18% of diarrheal diseases and 200,000 deaths annually worldwide, mostly among children in developing countries (Lopman et al 2016). Norovirus is the most common agent in outbreaks of gastroenteritis, due to its highly contagious nature and ease of spread through contaminated water and food. Norovirus is estimated to be responsible for almost 50% of the foodborne outbreaks (Patel et al 2009). A study involving 13 European countries reported 9430 norovirus foodborne outbreaks during 2002–2006 (Kroneman et al 2008), with 78 of these being from Sweden (Kroneman et al 2008). Norovirus-related outbreaks within the European Union have been mainly due to contaminated vegetables, bivalve mollusks, fruits, cereals, sprouts, herbs, and spices (EFSA and ECDC 2017, 2018).

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