Sewage. We know it's filled with germs that can make us sick, which is why we try to keep it far away from food and water supplies. But sewage should be the first place to go—if you’re looking for unknown viruses. So say the authors of an article in the journal mBio. [Paul Cantalupo, et al., "Raw Sewage Harbors Diverse Viral Populations"]



Only about 3,000 viruses have been catalogued by scientists. That might sound like a lot, but recent genomic studies have shown that it’s probably only a tiny fraction of the number that actually exist.



The article’s authors examined a sample of untreated wastewater in what you could call a poop-of-concept analysis. And they found 234 known viruses that can infect people, plants, animals and other organisms. They also detected genetic material from unknown viruses representing more than 50 different virus families. They even found traces of some viruses so different from ones already characterized that they couldn't even be placed in a rough category.



So there’s a virus-rich universe, ripe for exploration, waiting just at the end of the plumbing.

—Katherine Harmon

[The above text is a transcript of this podcast.]