Prevalence of Small Round Structured Virus Infections in Acute Gastroenteritis Outbreaks in Tokyo

Abstract

During the three-year period from 1984 to 1987, 506 acute gastroenteritis outbreaks involving 14,383 patients were reported to the Bureau of Public Health, Tokyo Metropolitan Government. Eighty (4,324 patients) of 150 outbreaks (4,860 patients) from which etiologic agents were not identified were subjected to virological investigation. Spherical particles of 28-32 nm in diameter with capsomere-like structures on the surface were detected in patients' stool specimens. Buoyant density of the particles appeared to be 1.36 to 1.40 g/ml in CsCl. Seroconversion to the particles was observed in patients by immune electron microscopy. From these observations, we concluded that the detected particles were members of small round structured virus (SRSV), and that they were implicated in the etiologically illdefined outbreaks encountered. Prevalence of SRSV infections in these outbreaks was examined by electron microscopy. SRSV was positive in 83.8% of the outbreaks, and 96.4% of the cases. SRSV-positive outbreaks usually occurred during winter in contrast to bacterial outbreaks which often occurred in the summer season. Of 80 outbreaks examined, 53 were associated with the ingestion of oysters, and the remaining 27 mostly with food other than oysters. Oyster-associated outbreaks usually occurred on a small scale, while unassociated ones on diverse scales ranged from family clusters to large outbreaks.

Sequence analysis of SRSV in fecal specimens from an epidemic of infantile gastroenteritis, October to December 1995, Japan

“…Foodborne infections by SRSV have been reported in winter in Japan [Hayashi et al, 1991;Oishi et al, 1992;Sekine et al, 1989;Taniguchi et al, 1979]. OTH-25/89/J-like and SMA/76/US-like viruses were detected as the causative agents in some cases.…”

“…Small round structured viruses (SRSV) are causative agents of airborne, foodborne, and waterborne outbreaks of vomiting and acute gastroenteritis [Kaplan et al, 1982;Morse et al, 1986;Sawyer et al, 1988;Sekine et al, 1989] in children and adults. SRSVs are often transmitted from person to person in hotels, restaurants, and public houses [McDonnell et al, 1995].…”

Trends in indigenous foodborne disease and deaths, England and Wales: 1992 to 2000

“…Estimates of foodborne NLV transmission vary from 68% 30 at one extreme to 7.6% 31 at the other. Given its high incidence it is important to use an accurate figure for percentage foodborne transmission.…”

A 2-year survey of the prevalence of enteric viral infections in children compared with contamination in locally-harvested oysters

“…In Japan, small round virus infections have been reported in several oyster-associated gastroenteritis outbreaks [7]. It has been suggested that bacteriological indicators such as standard plate counts and coliform indices may be poor indicators of the level of viral contamination [3,8,9].…”