Two gastroenteritis outbreaks caused by sapovirus in Shenzhen, China.

Human sapoviruses (SaVs) are a common cause of the acute gastroenteritis epidemic worldwide, and SaV outbreaks and infections have become more frequent in recent years. Since the end of December, 2015 to December, 2016, 2 gastroenteritis outbreaks occurred in 2 kindergarten classes (outbreaks A and B) in the Baoan district, Shenzhen, China. Feces and swabs were collected for laboratory tests of causative agents, and no bacterial pathogens were detected. Both the outbreaks were positive for SaV with a detection rate of 75% of symptomatic cases (6/8) in outbreak A and 71% (10/14) in outbreak B. For outbreak B, 1 of 3 asymptomatic teachers was detected to be SaV positive. The genome of some of the strains in this study was obtained, and the strains from outbreak A were genotyped into GII.3, while those from outbreak B were genotyped into GI.2, according to the phylogenetic analysis of the polymerase and the capsid region. No recombination was identified in either the GII.3 or GI.2 strain. GI.2 strains experience chronological variation, and the GI.2 strain in this study belonged to the most recent variant, which was observed from 2008 to 2016. The variation mainly occurred in the P domain from 1990 to 2016. Meanwhile, GII.3 strains shared greater similarity (>98.2%) at the amino acid identities; from 1999 to 2015, only 5 of them were in the predicted P domain. Our results suggest that it is necessary to conduct routine SaV surveillance and molecular characterization to further understand the SaV epidemic.