New research in Science links international wildlife trade to a higher risk of zoonotic spillover: traded species are about 50% more likely to carry pathogens that infect humans. The team reviewed 40 years of trade data and identified roughly 2,000 traded mammal species (≈25% of mammals). Live-animal markets emerged as likely hotspots, and experts call for better data, tighter oversight, and stronger biosecurity.
Global Wildlife Trade Linked To Higher Risk Of Diseases Jumping To Humans, Study Finds
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New research published in Science finds a clear link between the international wildlife trade and an increased risk of zoonotic spillover — diseases jumping from animals to humans. The study reports that species traded across borders are roughly 50% more likely to be associated with human-infecting pathogens than non-traded species, and it highlights live-animal markets as particular hotspots for transmission and pathogen evolution.
Study Approach and Key Findings
Researchers analyzed trade databases covering about 40 years and identified roughly 2,000 wild mammal species involved in international trade — around 25% of known mammal species. By combining trade records with data on which species are known to infect humans, the team found a strong correlation: the most-traded species carried the most pathogens capable of infecting people.
Why Live-Animal Markets Matter
More open, mixed settings such as live-animal markets create conditions that increase contact among diverse species and between animals and humans. Those environments can let pathogens jump between hosts and adapt, raising the likelihood of spillover events. The study found animals traded in such markets transmitted more diseases than those moved in more controlled circumstances.
"There's no safe trade," said Jerome Gippet, a co-author of the study. "As long as we continue trading species, we will expose ourselves to this problem."
Broader Risks and Policy Implications
The research team and outside experts note that both illegal and legal wildlife trade carry risks. Illegal trade can accelerate the spread of invasive species and evade health safeguards; legal trade requires careful management, stricter biosecurity, and better monitoring to reduce risk. Ann Linder of Harvard Law School praised the study for strengthening a long-held scientific suspicion but emphasized the need for more comprehensive and higher-quality data to understand and mitigate risk.
"We have a lot of case studies," said Colin Carlson, another co-author. "But we have a really poor evidence base about what the wildlife trade is actually doing."
The findings add weight to calls for improved surveillance of wildlife trade, stronger enforcement against illegal trafficking, and international coordination to reduce spillover risk — measures that public health officials say are critical to preventing future outbreaks.
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