The Poop Detective

Wastewater surveillance is one of the few tools that we can use to prepare for a pandemic and I am pleased that it is expanding rapidly in the US and around the world. Every major sewage plant in the world should be doing wasterwater surveillance and presenting the results to the world on a dashboard.

I was surprised to learn that wastewater surveillance is now so good it can potentially lock-on to viral RNA from a single infected individual. An individual with an infection from a common SARS-COV-2 lineage like omicron won’t jump out of the data but there are rare, “cryptic lineages” which may be unique to a single individual.

Marc Johnson, a virologist at the University of Missouri and one of the authors of a recent paper on cryptic lineages in wastewater, believes he has evidence for a single infected individual who likely lives in Columbus, Ohio but works in the nearby town, Washington Court House. In other words, they poop mostly at home but sometimes at work.

Twitter: First, the signal is almost always present in the Columbus Southerly sewershed, but not always at Washington Court House. I assume this means the person lives in Columbus and travels to WCH, presumably for work. Second, the signal is increasing with time. Washington Court House had its highest SARS-CoV-2 wastewater levels ever in May, and the most recent sequencing indicates that this is entirely the cryptic lineage.

Moreover the person is likely quite sick:

Third, I’ve tried to calculate how much viral material this person is shedding. (Multiply the cryptic concentration by the total volume). I’ve done this several times and gotten pretty consistent results. They are shedding a few trillion (10^12) genomes/day. What does this tell us? How much tissue is infected? It’s impossible to know for sure. Chronically infected cells probably don’t release much, but acutely infected cells produce a lot more. I gather a typical output in the lab is around 1,000 virus per infected cell. If we assume we are getting 1,000 viral particles per infected cell, that would mean there are at least a billion infected cells. The density of monolayer epithelial cells is around 300k cells/sq cm. A billion cells would represent around 3.5 square feet of epithelial tissue! Don’t get me wrong. The intestines have a huge surface are and 3 square feet is a tiny fraction of the total. But it’s still a massive infection, no matter how you slice it….My point is that this patient is not well, even if they don’t know it, but they could probably be helped if they were identified.

…If you are the individual, let me know. There is a lab in the US that can do ‘official’ tests for COVID in stool, and there are doctors that I can put you in contact with that would like to try to help you.

So if you poop in Columbus Ohio and occasionally in Washington Court House and have been having some GI issues contact Marc!

Hat tip to Marc for using the twitter handle @SolidEvidence.


Comments for this post are closed