Researchers Look To Quantify Viral Diversity Of Mammals

Brett Smith for – Your Universe Online

In late 2002, the SARS epidemic ripped through Southeast Asia and rattled worldwide confidence in medical technology’s capacity to prevent pandemics like those that have plagued human populations throughout history.

It was later discovered that the novel virus had spread to humans from mammals in Southeast Asia. By 2003, scientists had isolated the SARS virus from meat samples taken from a local market in Guangdong, China.

A new study published in the journal mBio attempts to get out in front of the next pandemic by estimating the total number of unknown diseases that could be found in mammals and the costs associated with identifying those viruses. Based on the work of a large international team, the report stated that there are at least 320,000 viruses in mammals awaiting discovery and collecting evidence of these viruses would cost approximately $6.3 billion.

“Historically, our whole approach to discovery has been altogether too random,” said lead author Simon Anthony, a scientist at the Center for Infection and Immunity (CII) at Columbia University. “What we currently know about viruses is very much biased towards those that have already spilled over into humans or animals and emerged as diseases. But the pool of all viruses in wildlife, including many potential threats to humans, is actually much deeper.”

“A more systematic, multidisciplinary, and One Health framework is needed if we are to understand what drives and controls viral diversity and following that, what causes viruses to emerge as disease-causing pathogens,” he added.

“For decades, we’ve faced the threat of future pandemics without knowing how many viruses are lurking in the environment, in wildlife, waiting to emerge. Finally we have a breakthrough — there aren’t millions of unknown virus, just a few hundred thousand, and given the technology we have it’s possible that in my lifetime, we’ll know the identity of every unknown virus on the planet,” said co-author Peter Daszak, president of the international conservation organization EcoHealth Alliance.

In the study, researchers collected almost 1,900 biological samples from flying fox bats in Bangladesh, which were captured and released. Through genetic analysis, researchers were able to identify 55 viruses in nine different families. Only five of these viruses were previously known and another 50 were newly discovered.

The research team then adapted an ecological technique to estimate that there should be another three viruses that could not be detected in the samples – increasing the estimate of total viruses in the flying fox to 58. When extrapolated to the more than 5,400 known mammals, researchers determined that there are a total of at least 320,000 unknown mammalian viruses.

The team also repeated the exercise for cost, to determine a total amount needed of $6.3 billion for collecting evidence of all these unknown viruses. They showed that limiting discovery to a more manageable 85 percent of estimated viral diversity would reduce the cost to $1.4 billion.

“By contrast, the economic impact of the SARS pandemic is calculated to be $16 billion,” Anthony said. “We’re not saying that this undertaking would prevent another outbreak like SARS. Nonetheless, what we learn from exploring global viral diversity could mitigate outbreaks by facilitating better surveillance and rapid diagnostic testing.”

“If we know what’s out there, we’ll be a lot better prepared when a virus jumps over into a human population,” he concluded.

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