2015 Volume 32 Issue 3 Pages 153-158
On 16 January, 2014, a large-scale mass food poisoning caused by Norovirus occurred in 19 elementary schools in Hamamatsu City, Shizuoka, Japan. Of 8,027 people eaten the bread, 1,271 were infected. The causative food was determined to be bread for school meals. At the Hamamatsu City Health Environment Research Center, stool specimens of patients and food handler, and lunch ingredients were inspected for causative agent. A total of 137 of the 435 (31.5%) specimens were positive for Norovirus G II by RT-qPCR assay. Phylogenetic analysis of the capsid N/S region nucleotide sequences indicated that these strains showed a high degree of similarity (≧98%) to G II.4 Sydney 2012 variant. The bread was processed using PANSORBIN Trap Method, G II.4 was detected from 2 specimens, and the quantity of virus was 2.4E+03, 3.3E+03 copies/g each. It was estimated that the polluted bread contaminated through the finger of the worker who held Norovirus or work clothes at the time of inspection work.