BBC - Future - The mystery viruses far worse than flu
However, perhaps the most enigmatic viruses of all are those which infect other animals. The ‘zoonotic’ pathogens include all the big names, from HIV to Nipah, having caused nearly every pandemic in human history. Just like the recent avian flu outbreak, the 1918 flu pandemic, which killed between 50 and 100 million people worldwide, began in birds.
Enter the virus hunters – scientists like Olival who travel the globe, looking for the source of the next pandemic. During the first phase of the US government’s disease surveillance program, from 2009-2014, “we found about a thousand new viruses”, he says. What is the undiscovered pool of viruses? “Oh, we estimate that it could be in the millions. There are probably millions of viruses out there that infect other mammals and could potentially infect people.”