Global Wildlife Trade Boosts Zoonotic Spillover Risk, Study Finds

Legal wildlife commerce was valued at $220 billion in 2022; illegal markets add up to $23 billion. Trade moves live mammals for pets, food, fashion, research and other uses, creating frequent human-animal contact worldwide.

Mongabay

Among 2,079 mammal species examined, 41 % could transmit at least one disease to humans, versus 6.4 % of non-traded species. Traded mammals were 50 % more likely to host zoonotic pathogens. Each additional decade of trade added roughly one extra human-infective pathogen. Of the 583 CITES-listed species traded internationally from 1980-2019, longer market presence correlated with higher pathogen counts.

Mongabay

The results show that both legal and illegal channels expand opportunities for pathogens to mutate and cross species barriers. Researchers call for a “One Health” approach—integrating human, animal and environmental health—to improve biosurveillance, data sharing and coordinated response across nations.

Mongabay

Study co-author Evan Eskew noted that ordinary pet sales are part of the risk, stressing that legal commerce is as hazardous as illicit trafficking. Meredith Gore pointed out that CITES focuses on conservation and lacks public-health enforcement tools. The authors urge expanded surveillance of all trade forms, domestic and international, to fill critical knowledge gaps.

Mongabay

Biosecurity analyst Jonathan Kolby warned that the 40-year dataset captures only a fraction of trade history, omitting many species and domestic networks. Ann Linder of Harvard Law School emphasized the scarcity of reliable data on trade scale and pathways, arguing that better evidence is essential for accurate risk assessment.

The Cool Down

The analysis depends heavily on international shipment records; domestic and regional exchanges remain poorly documented. Some species likely entered trade before appearing in CITES logs, while others may be missing entirely. Consequently, the precise magnitude of spillover risk cannot be mapped, and forecasts of future outbreaks stay uncertain.

Mongabay

• “the legal trade is likely to be just as risky for zoonotic disease transmission as the illegal trade.” — Evan Eskew, study author

Mongabay

• “There's no safe trade,” — Jerome Gippet, co-author

The Cool Down

• “We have a lot of case studies,” — Colin Carlson, co-author

The Cool Down

• “But we have a really poor evidence base about what the wildlife trade is actually doing.” — Ann Linder, associate director, Harvard Law School

The Cool Down

• “You don’t know what you don’t know,” — Meredith Gore, co-author

Mongabay

The team recommends extending biosurveillance to legal markets, improving international data exchange, and embedding wildlife-trade considerations into public-health policy. Enhanced monitoring of live-animal markets and stricter regulation of all trade channels are presented as essential steps to curb future zoonotic threats.

Mongabay