A three-stage hierarchical strategy for real-time containment of transboundary diarrheagenic viruses via aircraft-to-community wastewater surveillance

Globalization of air travel accelerates transboundary dissemination of enteric pathogens, yet conventional border screening fails to capture asymptomatic infections, creating critical surveillance blind spots. This study establishes a three-stage hierarchical early-warning framework integrating (i) mining open-source epidemic intelligence, (ii) aircraft wastewater (AW) surveillance, and (iii) community wastewater (CW) monitoring to track viral importation and subsequent local transmission. Using the Seoul–Xi'an route as a proof-of-concept during the 2024–2025 winter–spring season, we integrated quantitative PCR and high-sensitivity hybrid-capture sequencing (HybCapSeq) of AW with nanopore-based clinical genomics and structured epidemiological questionnaires to resolve viral transmission chains. Results demonstrated that viral concentrations of six diarrheal pathogens in AW exhibited high-frequency fluctuations, contrasting with smoother, sustained elevations in CW. AW surveillance detected continuous norovirus (NoV) introduction from November 2024, preceding community outbreaks by 2–3 months. Comparative genomic analysis revealed that flight-associated importation initiated 12 cryptic local transmission chains. Phylogenetically, NoV GII.17 formed a Korean-specific monophyletic lineage with Xi'an strains nested within, indicating transboundary spread. Critically, clinical isolates exhibited extreme genetic homogeneity with local CW strains and the Korean AW strain. Epidemiological investigation confirmed that 85.7% (6/7) of pediatric cases had travel history to South Korea or close contact with returnees within 14 days prior to illness onset, providing closed-loop genomic and epidemiological evidence of aviation-imported transmission. By bridging aviation surveillance with CW epidemiology through closed-loop genomic-epidemiological validation, this framework provides a scalable template for mitigating transboundary infectious disease spread and strengthening global health security.