Norovirus is a leading cause of acute gastroenteritis and spreads efficiently in closed, mobile cohorts such as organized travel groups. This case is notable for the real-time detection and genomic confirmation of a cross-border outbreak at a port of entry, including near-identical Norovirus GΙΙ.17P17 genomes and documented asymptomatic carriage, illustrating the practical value of integrated metagenomic surveillance in border health operations. On July 21, 2024, 26 travelers arrived at Shanghai Port after a 12-day group tour in Europe. Clinical interviews identified 15 individuals (57.7%) with diarrhea, nausea, dizziness, and abdominal pain; no hospitalizations occurred. On-site anal swab testing was negative for SARS-CoV-2, influenza A and B, Vibrio cholerae, and Escherichia coli. RT-qPCR detected Norovirus GII in 10 samples (38.5%), including two asymptomatic individuals. Metagenomic sequencing generated near-complete genomes for all RT-qPCR–positive samples, which were 99.9–100% identical and classified as Norovirus GΙΙ.17P17, confirming a cross-border outbreak within the travel cohort. Prompt public health response measures were initiated by Shanghai Customs and CDC authorities. This case demonstrates the feasibility and impact of rapid, genomically informed surveillance at the border for detecting and characterizing travel-associated enteric virus outbreaks. The findings underscore the need for robust port-of-entry monitoring, rapid diagnostics, and integrated genomic analysis to mitigate transmission in group travel settings.
Liu et al. (Wed,) studied this question.