Wildlife trade drives animal-to-human pathogen transmission over 40 years

The wildlife trade affects a quarter of terrestrial vertebrates and creates novel opportunities for cross-species pathogen transmission. Yet its contribution to animal-to-human pathogen transmission has rarely been quantified at global scale. We compiled four large datasets to link 40 years of international wildlife trade to mammal–pathogen associations: legal trade records (CITES and LEMIS), seizures of illegal trade (DSW), and the CLOVER database of >190,000 mammal–pathogen interactions. Focusing on wild mammals, and accounting for phylogeny, geography, research effort, synanthropy and wild‐meat use, we asked how trade status and trade history shape pathogen sharing with humans.We show that traded mammals are 1.5 times more likely to share at least one pathogen with humans than non-traded mammals (41% vs 6.4% of species). Live-animal markets further elevate risk: species traded alive are more likely to be zoonotic hosts and, among traded mammals, share on average ~1.5 times more pathogens with humans than species traded only as products. Illegal trade is also associated with a higher number of shared pathogens compared to species traded exclusively through legal channels.Crucially, we find that the time spent in trade is a strong predictor of cross-species pathogen sharing. Using 236,000 CITES records for 583 mammal species  between 1980 and 2019, we estimate that a wild mammal species acquires, on average, one additional shared pathogen with humans for every decade it is present in global wildlife trade. This implies that as more species enter and persist in wildlife markets, new zoonotic links will continue to emerge.Our results highlight wildlife trade as a central interface for pathogen exchanges between wild animals and humans. They argue for integrating disease risk reduction into wildlife trade governance – through improved biosurveillance, regulation of live and high-risk trade, and trade volume reduction – as a core pillar of both biodiversity conservation and pandemic prevention agendas.