title: Occurrence of norovirus infections unrelated to norovirus outbreaks in an asymptomatic food handler population.
abstract: Norovirus (NV) is the most common causative agent of nonbacterial gastroenteritis. Reports of surveillance of NV in facilities that reported outbreaks are frequently found in publications, but reports of that in facilities without outbreaks are not found. We investigated the molecular epidemiology of NV isolates derived from asymptomatic food handlers working at a non-outbreak food catering facility in Hokkaido, Japan, from February to March in 2005 and January to February in 2006 by RNA polymerase gene sequencing. Approximately 12% (20/159) of the samples were positive for genogroup II (GII; 10.1% in 2005 and 14.2% in 2006). The GI genotypes were not detected. The data from the phylogenetic analysis indicated that, among the 20 strains detected, 13 strains were GII/genotype 2 (GII/2), two were GII/3, three were GII/8, and two were GII/12. GII/4, which has been found most frequently in recent outbreaks worldwide, including Japan, was not detected. We found that one individual was coinfected with two genotypes, GII/2 and GII/12. This is the first report of the detection of NV genotypes in asymptomatic food handlers working at a non-outbreak facility. The excretion of NV from healthy individuals may be an infection source of NV outbreaks as well as other food-borne diseases.
authors.affiliation: Department of Microbiology, Sapporo Medical University School of Medicine, S1-W17, Chuou-ku, Sapporo, Hokkaido 060-8556, Japan.
authors.forename: Tamaki
authors.initials: T
authors.lastname: Okabayashi
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yokota
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohkoshi
authors.forename: Hironori
authors.initials: H
authors.lastname: Ohuchi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Koichi
authors.initials: K
authors.lastname: Yano
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Fujii
mesh_terms: D017250:Caliciviridae Infections / Q000453:epidemiology / Q000503:physiopathology / Q000821:virology; D002353:Carrier State / Q000453:epidemiology / Q000503:physiopathology / Q000821:virology; D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D005522:Food Services / Q000145:classification*; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D029322:Norovirus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence