New research has uncovered a surprising trend in viral transmissions between humans and animals. According to a study published in Nature Ecology & Evolution, humans are responsible for passing viruses to animals at twice the rate of animals transmitting viruses to humans.
The comprehensive analysis examined nearly 12 million virus genomes, identifying almost 3,000 instances of cross-species transmission. Of these, 79 percent involved viruses moving between animal species, while the remaining 21 percent involved humans. Notably, 64 percent of the human-related transmissions were human-to-animal, a phenomenon known as anthroponosis, compared to 36 percent that were animal-to-human, or zoonosis.
The study highlights the significant impact humans have on animal health, affecting a wide range of species including pets like cats and dogs, domesticated animals such as pigs and cattle, birds like chickens and ducks, and wild animals including raccoons and various primates. Wild animals were particularly susceptible to human-to-animal virus transmissions.
Lead author Cedric Tan from the University College London emphasized the environmental implications of these findings. \"This really highlights our enormous impact on the environment and the animals around us,\" Tan said.
While zoonotic transmissions have long been a major concern due to their potential to spark pandemics, the study sheds light on the often-overlooked reverse flow of viruses from humans to animals. Many of these transmissions do not result in widespread disease, as the viruses may be poorly adapted to their new hosts. However, some can lead to significant outbreaks or become endemic.
Francois Balloux, co-author and director of the UCL Genetics Institute, pointed out that pathogens like bird flu H5N1 and historical diseases such as the Black Death originated from animal sources. The study underscores the importance of monitoring both zoonotic and anthroponotic transmissions to better understand and mitigate future health risks.
Reference(s):
Humans give more viruses to animals than they give us: study
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