The observation that most viruses that cause human illness come from other animals has led some researchers to try to “predict zoonotic risk” to guess which virus will strike us next. However, in an essay published on April 20 in the open access journal PLOS biology, led by Dr Michelle Wille of the University of Sydney, Australia, with co-authors Jemma Geoghegan and Edward Holmes, it is proposed that these zoonotic risk predictions have limited value and will not tell us which virus will cause the next pandemic. Instead, we should target the human-animal interface for intensive viral surveillance.
So-called zoonotic viruses have been the source of epidemics and pandemics in humans for centuries. This is exactly what is happening today with the COVID-19 pandemic: the novel coronavirus responsible for this disease – SARS-CoV-2 – has emerged from an animal species, although exactly which species is uncertain.
Therefore, a key question is whether we can predict which animal or group of viruses is most likely to cause the next pandemic. This has led the researchers to attempt to “predict zoonotic risk,” in which they attempt to determine which virus families and host groups are most likely to carry potential zoonotic and / or pandemic viruses.
Dr Wille and his colleagues identify several key issues with attempts to predict zoonotic risk.
First of all, they’re based on tiny data sets. Despite decades of work, we have probably identified less than 0.001% of all viruses, even mammalian species from which the next pandemic virus will likely emerge.
Second, these data are also heavily biased in favor of viruses that infect humans or livestock the most, or that are already known to be zoonotic. The reality is that most animals have not been studied for viruses, and viruses evolve so rapidly that these surveys will soon be obsolete and therefore of limited value.
Rather, the authors argue that a new approach is needed, involving extensive sampling of animals and humans at the places where they interact – the animal-human interface. This will allow new viruses to be detected as soon as they appear in humans and before they cause a pandemic. Such enhanced surveillance can help us prevent something like COVID-19 from happening again.
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