sciencehabit writes "Ebola, HIV, influenza, MERS. Plenty of animal viruses cause devastating diseases in humans. But nature might have many more in store. In a new study, U.S. researchers estimate that there are more than 320,000 unknown viruses lurking in mammals alone (abstract). Identifying all the viruses in mammals would be a huge boon to scientists and epidemiologists, Daszak says. If an animal virus begins spreading to humans, they could use the new sequences to quickly pinpoint its source. In the lab, they could study the newfound viruses to see which are most likely to jump to humans and then prepare vaccines or drugs, he says. 'It would be the beginning of the end for pandemics.' A complete viral inventory would also carry a hefty price tag: about $6.3 billion, the authors estimate. 'But you have to put that into perspective,' says Daszak, pointing to the 2003 SARS outbreak. That pandemic alone is estimated to have cost between $15 billion and $50 billion in economic losses."