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A recent study indicates that humans transmit more viruses to both domestic and wild animals than they contract from them.
Researchers from University College London (UCL) examined all viral genetic sequences that are accessible to the public in order to determine how and where viruses have spread from one host to another, infecting different vertebrate species – animals that possess a backbone and skeleton.
Studying the evolution and transmission of viruses across different hosts can aid in identifying the origins of emerging viral diseases in both humans and animals.
One way to approach humans is to view them as a single point in a vast network of hosts that are constantly sharing pathogens, rather than just a source of zoonotic bugs.
Many contagious illnesses stem from animal viruses, and when these transfer to humans through zoonosis, they can lead to outbreaks, epidemics, and pandemics, such as the Ebola, flu, and Covid-19 crises.
Experts recommend that due to the significant influence of these illnesses on the well-being of the general population, humans have typically been viewed as a receptacle for viruses rather than a origin, with the transmission of viruses from humans to animals being given much less consideration.
In the recent research, it was discovered that there were approximately double the amount of host transfers from humans to other animals (referred to as anthroponosis) compared to transfers from animals to humans.
Furthermore, they discovered additional instances of animals infecting other animals without any involvement from humans.
The researchers claim that their results emphasize the underestimated reality of human viruses frequently transmitting from humans to both wild and domestic animals.
“We need to view humans as simply a single point within a larger network of hosts constantly passing pathogens back and forth, rather than just a recipient of zoonotic infections,” stated Professor Francois Balloux of the UCL Genetics Institute.
Discovering the mechanisms behind the evolutionary process of viruses and their ability to infect various hosts within the tree of life may aid in our understanding of the emergence of new viral diseases in both humans and animals.
Cedric Tan is currently a PhD student studying Computational Social Science.
By studying the transfer of viruses between animals and humans, in either direction, we can gain a greater understanding of viral development and potentially be better equipped to handle future outbreaks and epidemics of new diseases. This research can also contribute to conservation efforts.
The research team utilized tools to analyze approximately 12 million publicly available viral genomes for the study.
The researchers examined the evolution of 32 different families of viruses and traced their past transfers between hosts. They also analyzed which sections of the viral genetic material underwent mutations during these transfers.
The research discovered that, typically, when a virus jumps hosts, there is an uptick in genetic variations or mutations within the virus. This reflects the virus’s need to adapt and improve in order to effectively infect its new host.
Additionally, viruses that have already infected numerous animal species exhibit less pronounced signs of this adaptive phenomenon, implying that viruses with wider ranges of hosts may possess characteristics that enhance their ability to infect a variety of hosts.
Cedric Tan, a doctorate student at UCL Genetics Institute and Francis Crick Institute and the primary author of the study, stated that transmission of viruses from humans to animals can have detrimental effects on the animals and potentially endanger the species. Additionally, it could also lead to new issues for humans, such as food scarcity, as demonstrated by the need to cull large numbers of livestock due to the H5N1 bird flu strain in recent years.
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Moreover, in the event that a virus transmitted by humans spreads to a different species, there is potential for the virus to persist even after it has been eliminated in humans. This could also lead to the development of new characteristics before ultimately infecting humans once more.
The knowledge of why and how viruses adapt to infect various hosts in the larger tree of life can aid in our understanding of the emergence of new viral diseases in both humans and animals.
The results are published in the journal Nature Ecology and Evolution.
Source: independent.co.uk
