Mammals Home to an Estimated 320,000 Unknown Viruses

About 320,000 yet-to-be discovered viruses could be living in mammals, according to a new study. Understanding these viruses could help take precautions to prevent major viral outbreaks.

However, collecting evidence about the viruses is an expensive affair. Researchers estimate that identifying the viruses could cost $6.3 billion and if the study is limited to about 85 percent of the viruses, the cost would still be something around $1.4 billion.

They claim that the cost of identifying all viruses is a fraction of the cost of dealing with major diseases caused by viruses.

 About 70 percent of all diseases are caused by viruses that cross-over from animals to humans. Yet, there have been very few studies that try to estimate the number of viruses in animals.

"Historically, our whole approach to discovery has been altogether too random," said Simon Anthony, D.Phil, a scientist at the Center for Infection and Immunity (CII) at Columbia University. Anthony added that researchers only study the viruses that have already migrated from animals to humans, but there are several other animal viruses that have the capacity to jump to humans and cause disease.

For the study, researchers from CII and EcoHealth Alliance analyzed 1,897 biological samples from bats in Bangladesh. The flying fox- a type of bat- found in Bangladesh is home to several disease-causing Nipah viruses. In the lab, researchers found 55 viruses, of which only five were previously known.

The scientists then used statistical methods to extrapolate this figure to all 5,486 known mammals. They concluded that there might be about 320,000 viruses in all animals.

"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 Peter Daszak, PhD, corresponding author and president of EcoHealth Alliance, according to a news release.

The study, "A strategy to estimate unknown viral diversity in mammals," is published in the journal mBio.

A similar project called PREDICT has so far discovered about 240 new viruses in many parts of the world. According to researchers, identifying viruses will not prevent a disease outbreak, but will help develop an early warning system, BBC reported.