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Viruses’ biological features help to predict epidemics
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Researchers have identified numerous biological features that seem to determine the likelihood that a virus will be transmitted between humans, and that this information can help predict epidemics.
“By identifying the major biological features of successfully emerging viruses, our analysis can be used to generate broad-scale predictions of the likelihood that a virus of a specific family will achieve human-to-human transmission and hence epidemic spread,” Jemma L. Geoghegan, PhD, of the Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, and colleagues wrote.
Geoghegan and colleagues aimed to investigate why some viruses that are spread from animals to people — such as the H5N1 and H7N9 subtypes of avian influenza — show a limited ability for human-to-human transmission, while others like Ebola virus and Middle East respiratory syndrome coronavirus are efficiently transmitted this way.
“Such different outcomes of cross-species transmission highlight the importance of revealing the biological factors that determine why only a subset of viruses are able to establish productive infections in humans,” they wrote in the Proceedings of the National Academy of Sciences.
Zika, dengue called ‘exception rather than rule’
Geoghegan and colleagues compiled and analyzed a database of 203 human viruses and used statistical models to identify biological factors that were more often associated with sustained transmission among humans. Among other things, they discovered that viruses transmitted by vectors are less likely to spread among humans.
“So, although diseases like dengue and Zika have received a great deal of attention, they are very much the exception rather than the rule,” Geoghegan said in a news release.
The findings showed that viruses with a low host mortality that are chronic, nonsegmented, nonvector-borne and nonenveloped had the highest likelihood of being transmitted among humans, Geoghegan and colleagues wrote. Viruses with a low host mortality and the ability to survive for an extended period of time have more time to spread, Geoghegan said.
“A good example of this is polyomaviruses — a family of viruses that infect humans but which rarely cause symptoms or illness,” she said in the release. “In contrast, viruses that possess a particular structure called an ‘envelope’ seem less able to emerge in humans because they are more easily degradable and not environmentally stable.”
Geoghegan and colleagues found that genomic features had little predictive power.
“Our analysis therefore reveals that multiple virological features determine the likelihood of successful emergence,” they wrote. – by Gerard Gallagher
Disclosure: The researchers report no relevant financial disclosures.
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