Here’s some news about poo studies! Yummy.
A few other facts first.
If you go for a Covid-19 test (which you actually can’t do now, because even our fancy schmancy, first world, private laboratories are completely overwhelmed), you will have a swab thrust into your head (hopefully through one of the holes in your nose) and that swab will be sent to the laboratory.
At the lab, they’ll wash the bits of stuff off the swab, apply a few chemicals to the juice, wave a magic scientific wand over the little test tube and and put it into a machine which looks for a specific chunk of the RNA – one which is usually tucked inside the SARS-CoV-2 virus. The chunk of RNA that the machine looks for is only found in the SARS-CoV-2 virus, so it won’t detect any of your DNA or RNA, nor the genetic bits of anything that you’ve been snorting recently.
The thing is, you can find this section of RNA anywhere that the virus is (like up your nose), just by looking for it. And equally, because it’s so specific to this virus, you know that wherever you find these chunks of RNA, that’s indicative that the virus is there.
For the purposes of this post (and basically all of the scientific rationale behind Covid-19 testing):
Chunk of RNA = SARS-CoV-2 virus
Hold that thought.
Next up: one of the big problems with this pandemic stems from the fact that (even if you have enough tests to go around), we have people who don’t know that they have got the virus (because they show no symptoms), but who are passing it on. And because those people aren’t unwell, they don’t go to get tested (because why would you?), and so we actually have very little idea how many people in any given community actually have the virus. This makes it difficult to work out how many people are likely to be sick in that community and that makes if difficult to successfully and efficiently allocate resources. Ugh.
There’s some good news though: when we are infected with viruses (yes, including SARS-CoV-2) – whether or not we are showing symptoms – we poo out viruses (yes, including SARS-CoV-2). And, as we’ve already deduced above, we can look for SARS-CoV-2 anywhere, just by looking for that bit of RNA.
Are you going where I’m going here? Yes: down to the local sewage farm.
Mariana Matus has spent years studying what comes out of human bodies in order to better understand what is happening inside us. The computational biologist helped develop heavy-duty devices that are about the size of a milk crate and can be lowered into manholes to dangle over wastewater:steadily sucking up a stream of urine and feces through a straw-like tube.
Is it lunchtime yet?
The process in the lab is just about the same as if they were testing you, except that instead of doing the science with a swab from up your nose, they do it on some poo juice.
Even better news is that it seems that an uptick in the amount of RNA (and therefore the amount of virus) in the community’s sewage predicts an increase in local Covid-19 cases by about a week.
This environmental surveillance data were compared to declared COVID-19cases at municipality level, revealing that members of the community were shedding SARS-CoV-2 RNA in their stool even before the first cases were reported by local or national authorities in many of the citieswhere wastewaters have been sampled.
It’s early days, but this sewage screening technology has been used to predict other viral outbreaks such as Norovirus and Hepatitis A and could give us some important insights into how widespread the virus is and where we might be about to see one of those already infamous spikes – allowing us to get ready to deal with it by changing rules and/or providing extra healthcare resources. In turn, this might limit the extent of the local outbreak.
(And it works the other way, too: we can note a decrease in wastewater virus levels and predict when to lift lockdowns appropriately.)
This isn’t a substitute for testing people, obviously. We don’t know whose poos we’re testing. But as a epidemiology management tool, it could be hugely useful. It should also assist when (if?) a vaccine for Covid-19 is rolled out, as general community prevalence of the virus will be a good indicator of both vaccine uptake and success.
The only downside is that someone has to wander around your local sewage farm, sucking up the effluent and testing it each day to get these numbers. So just thank your given deity that there are people willing (and possibly even excited) to do this work for the good of humanity.
Stay home. Stay safe. Poo regularly. Microbiology will do the rest.