Monitoring of Calicivirus among day-care children: Evidence of asymptomatic viral excretion and first report of GI.7 norovirus and GI.3 sapovirus in Brazil

Abstract

Caliciviruses (Norovirus and Sapovirus) are important causes of acute gastroenteritis, with Norovirus (NoV) considered the leading cause of epidemic non-bacterial acute gastroenteritis; however, molecular and epidemiological data of the circulating Calicivirus (CV) strains among day-care children are still considered scarce. The role of asymptomatic CV excretion on viral transmission also remains poorly understood. The aim of the present study was to monitor the occurrence of NoV and Sapovirus (SaV) in a day-care center and to describe the molecular epidemiology of the circulating strains. Genomic sequencing and phylogenetic analysis of the capsid region were carried out in CV positive samples obtained from children younger than 5 years, with or without diarrhea, between October 2009 and October 2011. A total of 539 fecal samples were screened for CV. Forty-three (8%) were positive for NoV and 25 (4.6%) for SaV. Surprisingly, positivity rates for CV were significant in asymptomatic children, and virus circulation was detected in every month of the study. Great genomic diversity of CV was observed, and the circulating NoV strains were: GII.6, GII.2, GII.1, GI.7, GII.4, and GI.1. The SaV genotypes GI.1 and GI.3 were also detected. Five CV outbreaks caused by distinct viral strains were documented. This study provides an insight on the genetic diversity of CV in a day-care in Central West Brazil, highlighting the probable role of asymptomatic viral excretion and the significance of semi-closed settings in the dissemination of these agents.

Asymptomatic children might transmit human parechovirus type 3 to neonates and young infants

“…This may also be the case for HPeV3, as it is closely related to enteroviruses, and most children develop HPeV3 infection during infancy and become seropositive during childhood [11]. Analysis of stool or throat-swab samples confirmed asymptomatic infection for viruses such as enterovirus 71, [21] echovirus 18, [22] the caliciviruses (norovirus and sapovirus), [23] and 2009H1N1 influenza virus [24]. Interestingly, asymptomatic infection with enterovirus 71 was reported in household members of patients [21].…”

Sapoviruses in Children With Acute Gastroenteritis From Manaus , Amazon Region, Brazil, 2010-2011

“…A research conducted in the state of Pará which is also located in the Amazon region, found a frequency a little higher (4.9%) among diarrheic children 17 . A recent study conducted in a day-care in Midwest Brazil detected SaVs in 4.6% of children, and the circulating genotypes were GI.1 and GI.3 19 .…”

“…Nevertheless, in Brazil, there are limited data, considering the small number of studies available 16 , 17 , 18 , 19 . Thus, the present study aimed to investigate the SaV occurrence among hospitalized children with acute gastroenteritis from Manaus, Amazonas State, and also to improve the data on the molecular epidemiology of this virus in Brazil.…”

Norovirus prevention and the prevalence of asymptomatic norovirus infection in kindergartens and primary schools in Changzhou, China: Status of the knowledge, attitudes, behaviors, and requirements

“…Similarly, 8% were positive for NoV of 539 stool specimens obtained from 56 children aged 6-55 months who attended a daycare center in Brazil. 19 On the other hand, a Korean study 20 indicated that 3.5% and 5.5% of children younger than age 6 years from kindergartens in that country are asymptomatically NoV positive in summer and winter, respectively. On the contrary, A Danish research group 21 showed a low asymptomatic infection rate (1.5%) of Danish children younger than age 5 years.…”