May 05, 2024 18:00:00

Research results show that viruses are much more likely to be transmitted from 'humans to animals' than from 'animals to humans'

The COVID-19 pandemic has many people worried about

zoonotic diseases transmitted by animals such as bats, rats, and birds. However, a new study that analyzed the genomes of various viruses has revealed that viruses are more likely to be transmitted from humans to animals than from animals to humans.

The evolutionary drivers and correlates of viral host jumps | Nature Ecology & Evolution
https://www.nature.com/articles/s41559-024-02353-4

Humans pass more viruses to other animals than we catch from them | UCL News - UCL – University College London
https://www.ucl.ac.uk/news/2024/mar/humans-pass-more-viruses-other-animals-we-catch-them

One Animal Spreads More Viruses Than Any Other And It's Not What You'd Think: ScienceAlert
https://www.sciencealert.com/one-animal-spreads-more-viruses-than-any-other-and-its-not-what-youd-think

Many of the emerging infectious diseases that threaten modern society are caused by viruses that circulate in animals and then infect humans. However, while the impact of these zoonotic diseases on society has been highlighted, the fact that viruses can also be transmitted from humans to animals has not received much attention.

So a team of researchers from University College London developed a tool to analyze 12 million viral genomes from a public database, reconstructing the evolutionary and host-shift history of 32 virus families and determining which parts of the viral genome mutated during migration between hosts.

The researchers found that the likelihood of a virus adapting to a new host animal (host jump) was nearly twice as high when the virus was transmitted from humans to other animals as when it was transmitted from animals to humans, and this pattern held true for most virus families they analyzed.

Humans are just one type of animal that the virus infects, and are only one part of a larger network of hosts. 81% of the estimated host jumps identified in this study did not involve humans.

Professor François Barraud, co-author of the paper, said: 'We should think of humans not as a reservoir of zoonotic diseases, but as one node in a vast host network with a continuous exchange of pathogens. By studying and monitoring the spread of viruses between animals and humans, we can better understand viral evolution and prepare for future outbreaks and epidemics of emerging infectious diseases.'

'When humans transmit viruses to animals, it can harm those animals and threaten the conservation of species,' said lead author Cedric Tang, a PhD student. 'Furthermore, it could create new problems by affecting food security if large numbers of livestock need to be culled to prevent an outbreak, as has happened recently with the H5N1 avian influenza .'