Study Finds Traded Mammals 50 Percent More Likely to Share Pathogens with Humans

A study published in the journal Science on Thursday examined the spillover risks from the wildlife trade. Researchers analyzed data from over 2,000 traded mammal species, comparing it to international trade records and pathogen databases. The analysis covered both legal and illegal aspects of the trade.

The study determined that 41 percent of traded mammals share at least one pathogen with humans. 4 percent of mammal species not involved in breeding, transportation, buying, or selling share such pathogens. 5 times more likely to share pathogens with humans than non-traded mammals.

Jérôme Gippet, a postdoctoral researcher at the University of Fribourg and lead author of the paper, commented on the results.

“It was surprising to find such a clear signal between this trade and the number of pathogens shared between [mammals and] humans.”

Gippet added that the findings indicate the wildlife trade promotes pathogen transmission from animals to humans. The study connects the wildlife trade to pathogen emergence, noting conditions in the trade such as cramped and unsanitary environments for animals.

Past outbreaks provide context for these risks. The SARS outbreak in 2002-2003 was traced to the civet cat trade, and the Ebola outbreak in West Africa from 2014 was linked to bushmeat consumption or contact.

A World Health Organization committee concluded last year that the weight of available evidence suggests COVID-19 emerged from a zoonotic spillover, though it has not excluded a laboratory leak. Scientists not involved in the study described it as a definitive quantification of spillover risks from the wildlife trade.

Prof. Edward Holmes, an evolutionary biologist and virologist at the University of Sydney, noted the scale of the analysis as a key factor in its significance. The wildlife trade affects global health by facilitating pathogen transmission. Stakeholders include traders, consumers, and public health officials.

Future steps may involve policy measures to regulate the trade and reduce risks, though the study does not specify recommendations.