Genetic analysis of sapoviruses detected in outbreaks and sporadic cases of acute gastroenteritis in Miyagi Prefecture, Japan

•Detection rate of SaV was 5.8% in sporadic cases and 1.7% in foodborne outbreaks.•Detection rate of SaV was 4.3% in nonfoodborne outbreaks.•GI.1 was the predominant genotype in sporadic cases and nonfoodborne outbreaks.•GI.1 was not detected in foodborne outbreaks.•The SaV infection control may differ depending on the genomic characteristics. Human sapovirus (SaV) causes sporadic and endemic acute gastroenteritis worldwide. However, little is known about the relationship between the mode of transmission and genetic characteristics of SaV. To investigate the molecular characteristics of SaV-associated acute gastroenteritis among sporadic cases, foodborne, and nonfoodborne outbreaks. We performed a systematic review of publications and genetic analysis of SaV in fecal specimens from 98 outpatients with acute gastroenteritis, 32 stool samples from 8 foodborne outbreaks, and 63 stool samples from 23 nonfoodborne outbreaks in Miyagi Prefecture, Japan from 1993 and between 2004 and 2020. Reverse transcription polymerase chain reaction (RT-PCR) was employed for the detection of SaV, and the partial capsid gene was sequenced for genotyping and phylogenetic analysis. The overall detection rate of SaV in sporadic cases, foodborne, and nonfoodborne outbreaks was 5.8, 1.7, and 4.3%, respectively. Genotypic analysis revealed GI.1 to be the predominant genotype in sporadic cases (31.5%) and nonfoodborne outbreaks (52.1%), whereas it was not detected in foodborne outbreaks. Some outbreaks occurred following sporadic cases with the same genotype. The distribution of SaV genotypes was different between foodborne outbreaks and other settings. The effective SaV infection control may differ depending on the genomic characteristics.