40,000 novel viruses identified in global urban metagenomic survey

A large-scale metagenomic analysis of samples from 102 cities across 31 countries has identified over 40,000 previously unknown viruses, some with potential to infect humans and other mammals. Scientists caution that most are not an immediate threat, but the findings expand the known virosphere and highlight urban environments as hotspots for viral diversity. The implications for pandemic preparedness are uncertain but warrant monitoring.