The global wildlife trade has been linked to major disease outbreaks, with a new study warning that it significantly increases the risk of pathogen spillover from animals to humans.

Although its long-term role in shaping disease transmission has remained unclear, researchers say new evidence shows that traded mammals are substantially more likely to share pathogens with humans than non-traded species.

The study, which analysed 40 years of global wildlife trade data, found that traded mammals are about 1.5 times more likely to share viruses, bacteria, fungi, or parasites with humans compared to species not involved in trade.

It also revealed that the longer a species remains in trade, the more pathogens it is likely to share with humans on average, one additional pathogen for every decade of trade exposure.

Researchers said this suggests that prolonged and repeated contact between humans and wild animals in trade systems increases the risk of future disease emergence, including potential epidemics and pandemics.

The global wildlife trade involves close human interaction with animals sold as pets, bushmeat, trophies, and for use in traditional medicine, fur, and biomedical research. Scientists noted that these interactions occur across multiple stages of the supply chain, harvesting, breeding, transport, market sale, and consumption, creating opportunities for pathogens to cross species barriers.

The study further showed that traded species have a 50 per cent higher probability of sharing at least one human-infecting pathogen. It also found that live-animal markets pose a higher risk, with species sold alive sharing about 1.5 times more pathogens with humans than those traded only as products such as meat or fur. Illegally traded species were also found to carry a higher pathogen burden than those traded through legal channels.

To arrive at these findings, researchers led by Dr Jérôme Gippet of the University of Fribourg and the University of Lausanne analysed global wildlife trade records from sources including CITES, LEMIS, and seized wildlife datasets, and linked them to a global database of mammal-pathogen associations.

They concluded that traded wildlife species are significantly more likely to act as reservoirs for zoonotic diseases, though they noted that shared pathogens do not always result in direct transmission to humans.

The researchers warned that expanding wildlife trade increases opportunities for new pathogens to emerge in humans, raising the risk of future outbreaks. They also called for stronger surveillance of wildlife and animal-derived products, improved regulation of trade systems, and reduced overall trade volumes to limit human-wildlife disease transmission risks.

According to them, existing global agreements such as CITES focus mainly on species conservation, but do not adequately address public health risks linked to pathogen spillover.

The study further noted that even indirect consumption choices, such as products derived from wildlife, contribute to the broader chain of disease risk, as human exposure begins from hunting and processing stages.

Researchers stressed that limiting unnecessary contact between humans and wild animals is essential to reducing the likelihood of future infectious disease outbreaks.