Key points:
- Monitoring RNA viruses in animal populations could help identify those that are most likely to emerge and spread rapidly in humans.
- In a new study, researchers identified 70 virus lineages that pose the biggest risk of causing the next global epidemic or pandemic.
- The team says viruses from other genetic backgrounds are unlikely to cause a high number of infections in humans.
A new study has identified 70 virus lineages—groups of related viruses—that pose the biggest risk of becoming the so-called Disease X that causes the next global pandemic.
The researchers focused on RNA viruses since they are the ones that cause many diseases—including the common cold, COVID-19 and measles—and have been responsible for most epidemics, or global pandemics, in recent history. Of course, the huge number of RNA viruses in circulation makes monitoring challenging.
For their study, published in Molecular Biology and Evolution, the researchers compared the development of strictly zoonotic viruses—those that spread from animals to humans, but not between people—with human-transmissible viruses, which can spread within human populations. The findings showed that viruses that can spread within human populations typically evolve separately from strictly zoonotic viruses.
For example, human-transmissible viruses often emerge when related viruses from the same lineage can already spread between humans. Strictly zoonotic viruses have historically not led to epidemics in human populations. Having a close relative that can infect humans, but not spread between them, does not appear to increase the risk of epidemic potential.
The research team caution that there is still a chance the next pandemic could come as the result of a strictly zoonotic virus—such as bird flu—or an entirely new virus. However, the findings offer a route to help streamline surveillance for Disease X among the vast number of RNA viruses in existence.
The University of Edinburgh-led research team traced the lineage of 743 distinct RNA virus species during the study. They concluded that viruses from other genetic backgrounds are unlikely to cause a high number of infections in humans.
“Viruses without the right ancestry don't seem to cause epidemics. Out of potentially huge numbers of mammal and bird viruses in circulation, we should concentrate on the ones that are related to existing human viruses with epidemic potential,” said study author Mark Woolhouse, professor of infectious disease epidemiology at the University of Edinburgh.