Science The closer and longer the contact between species, the higher the chances of transmission of pathogens. This rule of thumb applies to human-to-human contacts as well as contacts with other species. Gippet et al. examined trade data for wildlife species from the past 40 years and showed that the longer a species had been legally traded, the greater the likelihood that humans and the trade species will share some sort of pathogen (virus, bacterium, fungus, or parasite). The authors estimate that traded wildlife species share one additional pathogen with humans for every decade in the global wildlife market.
The wildlife trade is an important form of human-animal interaction that affects around a quarter of all mammal species. Multiple trade-related activities, including harvesting, breeding, warehousing, transport, market placement, and end use, create opportunities for cross-species pathogen transmission. As such, the human-animal interactions occurring throughout wildlife trade networks can lead to infectious disease outbreaks in humans, including epidemics and pandemics with major socioeconomic impacts. Although several high-profile outbreaks, including the emergence of HIV, the 2014 West African Ebola epidemic, the 2003 mpox outbreak in North America, and the COVID-19 pandemic, have been linked to traded wildlife, the long-term impact of the wildlife trade in shaping pathogen exchange between humans and wild animals remains unclear.