A new study by the University of Sydney and the Chinese Centers for Disease Control and Prevention in Beijing found more than 1,400 viruses in invertebrates, or animals without backbones such as worms, insects and spiders, living in and around human homes.

The study, published in the journal Nature, showed people are surrounded by viruses in their daily life, but only a few of those could harm human health.

"This groundbreaking study re-writes the virology text book by showing that invertebrates carry an extraordinary number of viruses -- far more than we ever thought," explained Professor Edward Holmes, from the Marie Bashir Institute for Infectious Diseases & Biosecurity and the School of Life and Environmental Sciences, who led the Sydney component of the project, in a statement. "Viruses are the most common source of DNA and RNA on earth. It is all literally right under our feet,"

For the study, the researchers used a new technique called "meta-transcriptomics" to profile more than 220 species of invertebrates across nine diverse animal phyla that have not previously been studied for viral diversity and evolution.

The researchers found a total of 1,445 viruses in invertebrates, which are way more than the usual number of viruses documented in any one study. Despite the large number of viruses found in animals without back bones, the researchers noted that only a few of these can be transferable to vertebrates and possibly infecting humans.

Furthermore, the study also suggests that viruses from RNA are likely to exist in every species of cellular life. Additionally, the researchers also noted that viruses may have originally come from invertebrates that has been infected with different kind of viruses for billions of years, as oppose to the millions of years that was believed in the past.

With their findings, the researchers hope to present a different view of the RNA virosphere that is more phylogenetically and genomically diverse than previously thought, providing a more solid foundation for studies in virus ecology and evolution.