Outbreak of sapovirus infection among infants and children with acute gastroenteritis in Osaka City, Japan during 2004–2005

Abstract

One hundred and twenty five fecal specimens were collected from sporadic cases of acute gastroenteritis in a pediatric clinic in Osaka City, Japan from July 2004 to June 2005 and tested for the presence of rotavirus, norovirus, sapovirus, astrovirus, and adenovirus by RT-multiplex PCR. Among diarrheal viruses detected, norovirus was the most prevalent (19.2%, 24 of 125), followed by group A rotavirus (18.4%, 23 of 125), astrovirus (1.6%, 2 of 125), and adenovirus (0.8%, 1 of 125), respectively. Interestingly, sapovirus infection was identified with high incidence of 17.6% (22 of 125). Sapovirus was subjected to molecular genetic analysis by sequencing. It was found that sapovirus detected in this study was classified into four genotypes (GI/1, GI/4, GI/6, and GI/8), and sapovirus GI/6 was predominant, followed by GI/8 and accounted for 81.8% (18 of 22) and 9.1% (2 of 22), respectively. It was noteworthy that sapovirus GI/6 infection was apparently confined within the period of 5 months (August 2004 through December 2004). This pattern of infection implied the outbreak of sapovirus GI/6 in these patients, which was the first outbreak of acute gastroenteritis attributed to sapovirus in Osaka City. Another interesting feature of the study was the appearance of two novel, naturally occurring recombinant sapoviruses circulating in the Japanese population studied. This report confirmed the presence as well as the importance of sapovirus causing acute gastroenteritis among Japanese infants and children.

Epidemiology and Genotype Analysis of Emerging Sapovirus-Associated Infections across Europe

“…SaVs have been reported as causes of occasional outbreaks in adults, but their prevalence seems to be increasing. Similar findings were reported recently from Sweden (15), Canada (22), Japan (8,(10)(11)(12)(13)24), and Hungary (23). In addition, food-borne outbreaks and several novel recombinant SaV strains have been identified (8,12,17,21,31).…”

“…NoV infections are common in all age groups and are responsible for about 80% of all acute-GE outbreaks (29). On the other hand, SaV infections are less common and known to cause disease primarily in children, usually under the age of 5 years (10,11,13,24). However, SaVs have recently been reported as an occasional cause of outbreaks in hospitals and other health care facilities.…”

Comprehensive Review of Human Sapoviruses

“…All reported intergenogroup recombinant strains were GIV (based on VP1 sequence), whereas they were clustered together with GII strains in the RdRp region (46,85,102,116,117). Intragenogroup recombinant strains within GI (118)(119)(120), GII (84,121,122), and GIII (123) have been identified.…”

Quantification and Genotyping of Human Sapoviruses in the Llobregat River Catchment, Spain

“…Viruses causing gastroenteritis are acknowledged as a major health concern, and human sapoviruses (SaVs) are increasingly recognized as a major cause of acute diarrhea, mainly in children, although their medical significance is still poorly defined (8,18,21). SaVs are members of the family Caliciviridae and are nonenveloped, positive-strand RNA viruses (5).…”