A metagenomic approach for microbial risk assessment and source attribution in high-risk ports of entry environments

The epidemiological characteristics of emerging infectious disease outbreaks in recent years have underscored the critical importance of controlling imported infectious diseases. In this study, we implemented dynamic tracking of microbial invasions by monitoring environmental microbes at the customs and ports. From July to September 2024, a total of 126 environmental samples were collected from three ports of entry in Shenzhen, China. Metagenomic analysis detected 55 non-viral microbial communities and 12 viral taxa. Among these, 26.8 % of the bacteria, 100 % of the fungi, 71.4 % of the protists, and none of the archaea exhibited potential pathogenic properties. Viruses were the most prevalent, including bacteriophages (100 %), unclassified viruses (96.8 %), giant viruses (27.8 %), fungal viruses (4.8 %), and vertebrate viruses (1.6 %). No statistical differences were observed in viral distribution across areas (χ²  = 18.70, P = 0.541), sites (χ²  = 14.02, P = 0.597), or ports of entry (χ²  = 10.27, P = 0.247). However, viral distribution varied significantly across three sampling months (χ²  = 21.06, P = 0.002), with a higher proportion of giant viruses detected in July. Thirty-nine and forty microorganisms were identified across the six areas and five sites, respectively, with relatively few area/site-specific microorganisms. Four distinct disinfection level zones were categorized: relatively safe zone, less safe zone, general disinfection zone and key disinfection zone. Two strains of viruses with potential pathogenicity were identified: pigeon circovirus and Influenza A virus (H4N2). This study established a metagenomics-based surveillance framework for microbial risk assessment in high-risk port environments and proposed a four-tier disinfection strategy to prioritize high-contact zones. Our findings highlighted environmental metagenomics as a critical complement to traveler screening and provided early warning signals for the prevention and control of imported infectious diseases.