A recent study conducted by researchers from University College London (UCL) reveals an unexpected finding - humans pass on more viruses to animals than they catch from them. This discovery challenges the conventional belief that zoonotic diseases, which originate in animals and spread to humans, pose the greatest risk to public health.

The UCL researchers analyzed tens of thousands of viral genomes available in public databases. By studying the genetic information within viruses, including the instances of species jumps, the team could determine the direction of transmission - whether the pathogens were passed from humans to animals (anthroponosis) or vice versa (zoonosis). Surprisingly, the study found that nearly two-thirds (64%) of the samples analyzed were transmitted to animals from humans.

Professor Francois Balloux, co-author of the study, emphasizes the need to perceive humans as an integral part of a vast network of hosts continuously exchanging pathogens, rather than solely a recipient of zoonotic bugs. This perspective enables a better understanding of viral evolution and improved preparedness for future outbreaks and epidemics of novel illnesses.

The findings have significant implications for wildlife conservation and human health. Lead author Dr. Cedric Tan highlights the potential conservation threat to species posed by viruses transmitted from humans. He cautions that human-transmitted viruses could impact food security, necessitating the culling of large numbers of livestock to prevent epidemics, as has been observed with the H5N1 bird flu strain in recent years. Additionally, viruses carried by humans that infect new animal species could persist and evolve, even after eradication in humans, potentially causing new problems.

Understanding the mechanisms behind viral jumps between different hosts across the tree of life becomes crucial in deciphering how new viral diseases emerge in both humans and animals, according to Dr. Tan. As an example, the origin of the COVID-19 pandemic has been a subject of intense debate. Some scientists believe the virus jumped to humans from bats in China, possibly through an intermediate species such as the raccoon dog or pangolin.

While the study sheds light on the overlooked aspect of human-to-animal transmission, it does not provide concrete evidence for the origin of COVID-19. The Wuhan Institute of Virology has been suggested as a possible bioengineering site, while others point to the Huanan seafood wholesale market in Wuhan, where various live animals were kept and sold. The investigation by the World Health Organization (WHO) earlier this year deemed all hypotheses regarding the origins of COVID-19 to be on the table, with the natural origins theory being the most likely.

The study's findings serve as a reminder of the intricate relationship between humans and animals in the spread of viruses. Further research and monitoring of virus transmission between species in both directions are essential for mitigating the risks of future viral outbreaks and protecting both human and animal health.

As the search for answers continues, experts remain wary that the ultimate truth behind the origins of COVID-19 may never be fully uncovered, leaving room for speculation and uncertainty.