A group of experts has argued that trying to survey all of the viruses in the animal kingdom is a futile effort, and that we should rather focus on those most likely to cross over at the interface of humans and animals.
The observation that most of the viruses that cause human disease come from other animals has led some researchers to attempt “zoonotic risk prediction” to second-guess the next virus to cause a global pandemic.
Zoonotic viruses, those that cross over from animal species into humans, have caused epidemics and pandemics in humans for centuries. This is exactly what is occurring today with the COVID pandemic: SARS-CoV-2—the coronavirus that causes the disease—emerged from an animal species, albeit which one is not yet known.
An essay published April 20th in the open access journal PLOS Biology, led by Dr Michelle Wille at the University of Sydney, Australia with co-authors Jemma Geoghegan and Edward Holmes outlines the great challenges in zoonotic risk prediction.
The authors argue that these zoonotic risk predictions are of limited value, and will not be able to predict which virus will cause the next great pandemic. Instead, they reason, the human-animal interface should be the target for intensive viral surveillance.
A key question is whether it is possible to predict which animal or which virus group will most likely cause the next pandemic. This has led to “zoonotic risk prediction,” in which researchers attempt to determine which virus families and host groups are most likely to carry potential zoonotic and/or pandemic viruses.
Dr Wille and her colleagues identified several key problems with zoonotic risk prediction attempts.
Firstly, they’re based on very small data sets. Despite decades of work, less than 0.001% of all viruses have likely been identified, even from the mammalian species from which the next pandemic virus is expected to emerge.
Second, these data are also already highly biased in favour of those the most infectious viruses of humans or agricultural animals, or are already known to be zoonotic. Most animals have in fact not been surveyed for viruses, and that viruses evolve so quickly that any such surveys will soon be out of date and therefore be of limited value.
The authors instead argue that a new approach is needed, not trying to futilely survey all the viruses in the wild but instead undertaking extensive sampling at the animal-human interface. This would enable the detection of novel viruses as soon as they appear in humans. This kind of enhanced surveillance could help us forestall the next pandemic.
Source: Phys.Org
Journal information: Wille M, Geoghegan JL, Holmes EC (2021) How accurately can we assess zoonotic risk? PLoS Biol 19(4): e3001135. doi.org/10.1371/journal.pbio.3001135
