Epidemiological and Genetic Characterization of Norovirus Outbreaks That Occurred in Catalonia, Spain, 2017-2019.

Eduard Anfruns-Estrada,Albert Bosch,Rosa M Pintó,Sara Sabaté,Nuria Torner,Susana Guix,Efrén Razquin,Conchita Izquierdo,Cristina Fuentes,Rosa Bartolomé,Nuria Soldevila,Lorena Coronas,Àngela Domínguez,Thais Cornejo Sánchez

doi:10.3390/v14030488

Abstract

Molecular characterization of human norovirus (HuNoV) genotypes enhances the understanding of viral features and illustrates distinctive evolutionary patterns. The aim of our study was to describe the prevalence of the genetic diversity and the epidemiology of the genotypes involved in HuNoV outbreaks in Catalonia (Spain) between 2017 and 2019. A total of 100 HuNoV outbreaks were notified with the predominance of GII (70%), followed by GI (27%) and mixed GI/GII (3%). Seasonality was observed for GII outbreaks only. The most prevalent genotypes identified were GII.4[P31] Sydney 2012, GII.4[P16] Sydney 2012 and GII.2[P16]. As compared to person-to-person (P/P) transmitted outbreaks, foodborne outbreaks showed significantly higher attack rates and lower duration. The average attack rate was higher in youth hostel/campgrounds compared to nursing homes. Only genotypes GI.4[P4], GII.2[P16], GII.4[P16], GII.4[P31] and GII.17[P17] were consistently detected every year, and only abundance of GII.2[P16] showed a negative trend over time. GII.4 Sydney 2012 outbreaks were significantly associated to nursing homes, while GII.2[P16] and GI.3[P3] were most frequently identified in youth hostel/campgrounds. The average attack rate was significantly higher when comparing GII.2[P16] vs. GI.4[P4], GII.2[P16] vs. GII.4[P31] Sydney 2012, and GII.6[P7] vs. GII.4[P31] Sydney 2012. No correlations were found between genotype and outbreak duration or age of affected individuals.

Highlights

ORF1 and ORF2 can occur, and this can lead to the appearance of novel strains containing different RNA-dependent RNA polymerase (RdRp) and VP1 combinations [6,7]
The main purpose of the study was to describe and analyse the prevalence and the genetic diversity of the different genotypes involved in human norovirus (HuNoV) outbreaks between 2017 and 2019 in Catalonia, the second most populated region in Spain with 7.7 million inhabitants
Human stool samples were collected from affected individuals during HuNoV outbreaks reported in Catalonia (Spain) through January 2017 to December 2019 in closed and semi-closed settings such as nursing homes, youth/campgrounds, long-term care facilities, schools and other institutions

Summary

Introduction

Human noroviruses (HuNoV) are recognized as the most prevalent agent, causing approximately. 17–18% of the total diarrheal diseases and 200,000 annual deaths [1,2]. They represent the leading cause of gastroenteritis outbreaks worldwide affecting all age groups, being mainly transmitted via an oral-fecal route [3] and with a seasonal pattern, as most of the outbreaks occur within cold months of the year [4]. Recombination between the overlap of ORF1 and ORF2 can occur, and this can lead to the appearance of novel strains containing different RdRp and VP1 combinations [6,7]. The diversity of existing circulating genotypes, including recombinant strains, is represented with a dual typing approach with information from both RdRp and VP1 proteins to allow a better follow-up of HuNoV strain evolution [8]

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