Epidemiological Characteristics of Norovirus Associated with Sporadic Gastroenteritis among Children from the 2006/2007 to 2011/2012 Season in Nara Prefecture, Japan

Abstract

The present study aimed to describe the epidemiological characteristics of norovirus (NoV) associated with sporadic gastroenteritis in regional populations of Nara Prefecture, Japan, from the 2006/2007 to 2011/2012 epidemic season. Fecal specimens of sporadic gastroenteritis collected between September 2006 and August 2012 in Nara Prefecture were examined for the presence of NoV by reverse transcription-polymerase chain reaction. The NoV genotype was determined by nucleotide sequence analysis. In total, 274 NoVs associated with sporadic gastroenteritis were identified. We detected 10 different NoV genotypes: GI/3, GI/4, GI/8, GII/2, GII/3, GII/4, GII/6, GII/7, GII/12, and GII/13. A high NoV detection rate of 35.9% was identified in 1-year-old children. Among the 274 NoV isolates, 142 were obtained from males and 131 were obtained from females (the source of one was unknown). The most prevalent genotype was GII/4, accounting for 117 of the 192 different NoVs identified by sequencing. More epidemiological data will be required to determine the epidemiological characteristics of NoVs in other areas of Japan.

Epidemiological Characteristics of Sapovirus and Human Astrovirus Detected among Children in Nara Prefecture, Japan, during the 2009/2010–2014/2015 Seasons

“…In contrast, the detection rate of HAstV among the 6 seasons was lowest during the 2010/2011 season (1.4z) and highest during the 2011/2012 season (7.3z). These rates were low when compared with the previously reported detection rates of NoV or RVA in Nara Prefecture (7,13). However, a total of 111 strains were detected, and these viruses were present during all the 6 seasons studied.…”

“…The annual observation period of gastroenteritis in the current study began in September and ended in August of the following year. Viral RNA was extracted as previously described (7). Reverse transcription-polymerase chain reaction (RT-PCR) was performed to screen for SaV and HAstV using SV-F11 and SV-R1 primers for SaV (8) and AC1?…”

“…The RT-PCR was performed using the PrimeScript One Step RT-PCR Kit Ver.2 (Takara Bio Inc., Shiga, Japan). Electrophoresis, amplified DNA purification, and direct sequencing were performed as previously described (7). Direct sequencing was performed by RT-PCR using the primers for SaV strains.…”

Temporal dynamics of norovirus determined through monitoring of municipal wastewater by pyrosequencing and virological surveillance of gastroenteritis cases

“…Outbreaks most frequently occur during cold weather (Ahmed et al, 2013;Lopman et 53 al., 2009;Mounts et al, 2000), and this seasonality is also observed in Japan (Mounts et al, 2000;Siebenga et al, 2009;Yoneda et al, 2014). Noroviruses are classified into five genogroups (GI-GV), which are further subdivided into at least 35 genotypes (Centers for Disease Control and Prevention, 2011;Zheng et al, 2006).…”

Epidemiology of gastroenteritis viruses in Japan: Prevalence, seasonality, and outbreak

“…Although several comprehensive articles have reported on the prevalence, genotype seasonality, and outbreaks of gastroenteritis viruses in Japan, no systematic literature reviews and meta‐analysis have been published. Many research articles reporting on several kinds of diarrheal viruses throughout Japan showed the prevalence of diarrheal viruses ranging from 30.2% to 70.4% [Iritani et al, ; Phan et al , ,, ; Akihara et al, ; Shimizu et al, ; Harada et al, ; Kitahori et al, ; Nakanishi et al, ; Kawada et al, ; Yoneda et al, ; Thongprachum et al, ]. Most recently, a 4‐year study of the viruses that caused diarrhea in Japanese pediatric outpatients revealed the prevalence of diarrheal viruses at 70.4% [Thongprachum et al, ].…”