Epidemiology of GII.4 and GII.2 norovirus outbreaks in closed and semi-closed institutions in 2017 and 2018

Abstract

Norovirus infections are a leading cause of acute gastroenteritis outbreaks worldwide, with genotypes GII.2 and GII.4 being the most prevalent. The aim of this study was to compare the characteristics of GII.2 and GII.4 norovirus outbreaks reported in Catalonia in closed or semi-closed institutions in 2017 and 2018. The epidemiological and clinical characteristics of GII.2 and GII.4 outbreaks were compared using the chi-square test or Fisher's exact test for categorical variables and the Mann–Whitney U test for continuous variables. Odds ratios and their 95% confidence intervals were estimated. 61 outbreaks were reported: GII.4 was the causative agent in 12 outbreaks (30%) and GII.2 in 9 outbreaks (22.5%). GII.2 outbreaks were detected more frequently in schools or summer camps (66.7%) and GII.4 outbreaks in nursing homes (91.7%) (p = 0.01). Ninety-three people were affected in GII.2 outbreaks and 94 in GII.4 outbreaks. The median age was 15 years (range: 1–95 years) in GII.2 outbreaks and 86 years (range: 0–100 years) in GII.4 outbreaks (p < 0.001). Nausea, abdominal pain, and headache were observed more frequently in persons affected by GII.2 outbreaks (p < 0.05). Symptomatic cases presented a higher viral load suggestive of greater transmission capacity, although asymptomatic patients presented relevant loads indicative of transmission capacity.

Prevalence of Human Norovirus GII.4 Sydney 2012 [P31] between 2019 and 2021 among Young Children from Rural Communities in South Africa

“…Our findings are comparable with studies demonstrating the role of GII in symptomatic infections [ 42 , 61 , 62 ]. Genogroup II strains have been associated with the majority of outbreaks worldwide [ 15 , 63 ]. In contrast, the GI group was found to be more prevalent amongst control cases in this study.…”

Norovirus Epidemiology and Genotype Circulation during the COVID-19 Pandemic in Brazil, 2019–2022

“…Previous studies with children under five age who were hospitalized with AGE in Indonesia [70] and Germany [41] also detected GI.4 and GI.3 as the most frequently detected genotypes, respectively. Recently, a study on AGE outbreaks in closed or semi-closed institutions in Catalonia, Spain, between 2017 and 2018, showed that GI.4 (35.7%) and GI.3 (14.3%) were the main genotypes among GI noroviruses [71]. More recently, another study in Spain, has reported the detection of the rare recombinant genotype GI.5[P4], also detected in our study, as the cause of a large foodborne outbreak of AGE occurred in a hotel in 2021 [72].…”

Common and Potential Emerging Foodborne Viruses: A Comprehensive Review

“…In comparison, non-GII.4 genotypes, such as GI.3, GI.6, GI.7, GII.3, GII.6 and GII.12, are more often transmitted to humans via foodborne routes [21]. Norovirus genotypes GII.2 and GII.4 are mostly implicated in outbreaks of gastroenteritis, especially in closed institutions such as schools, nursing homes and summer camps [22]. However, genogroup GI strains are more often linked to waterborne outbreaks of norovirus [23].…”