ABSTRACT
During a survey of human rotaviruses in Okayama Prefecture, Japan in the 2011-2012 rotavirus season (between September 2011 and August 2012), G3P[8] was found to be a predominant genotype overall. However, G1P[8] emerged in the latter half of the season. To clarify the genetic background of the G1P[8] strains, the VP7, VP4, VP6, NSP4, and NSP5/6 genes of the strains were sequenced and genotyped. As a result, it was demonstrated that the strains with two different genotype constellations (G1-P[8]-I1-E1-H1 and G1-P[8]-I2-E2-H2) prevailed in the season. The G1P[8] strains possessing the DS-1-like VP6, NSP4, and NSP5/6 genes (the DS-1-like G1P[8] strains), which should reveal a short electropherotype, were originated from possible intergenogroup reassortment events. The DS-1-like G1P[8] strains accounted for 74.1% of all G1P[8] strains and were detected continuously throughout the season but not in the preceding season, indicating the possibility of new introduction and rapid spreading of these strains in the 2011-2012 season. The results suggest that the intergenogroup reassortants, considered generally unstable, can spread rapidly and become relevant.
Subject(s)
Antigens, Viral/genetics , Capsid Proteins/genetics , Genetic Variation , Rotavirus Infections/epidemiology , Rotavirus Infections/virology , Rotavirus/classification , Rotavirus/genetics , Viral Nonstructural Proteins/genetics , Adolescent , Child , Child, Preschool , Female , Genotype , Humans , Infant , Japan/epidemiology , Male , Molecular Epidemiology , Molecular Sequence Data , Prevalence , RNA, Viral/genetics , Rotavirus/isolation & purification , Sequence Analysis, DNAABSTRACT
There have been only 2 reports of a large-scale foodborne outbreak arising from Salmonella enterica serotype Braenderup infection worldwide. On August 9, 2008, an outbreak originating in boxed lunches occurred in Okayama, Japan. We conducted a cohort study of 786 people who received boxed lunches from a particular catering company and collected 644 questionnaires (response rate:82%). Cases were defined as those presenting with diarrhea (â§4 times in 24h) or fever (â§38â) between 12 am on August 8 and 12 am on August 14. We identified 176 cases (women/men:39/137);younger children (agedï¼10 years) appeared to more frequently suffer severe symptoms. Three food items were significantly associated with higher risk of illness;tamagotoji (soft egg with mixed vegetables and meat) (relative risk (RR):11.74, 95% confidence interval (CI):2.98-46.24), pork cooked in soy sauce (RR:3.17, 95% CI:1.24-8.10), and vinegared food (RR:4.13, 95% CI:1.60-10.63). Among them, only the RR of tamagotoji was higher when we employed a stricter case definition. Salmonella Braenderup was isolated from 5 of 9 sampled cases and 6 food handlers. It is likely that unpasteurized liquid eggs contaminated by Salmonella Braenderup and used in tamagotoji caused this outbreak.
