COVID-19 Day 47: The Newest Coronavirus Test is Full of Crap

C19_crapytest

Researchers in Paris have developed a way to test for a rise in new coronavirus cases, our crap. Specifically, toilet wastewater in our sewer systems. If these tests prove to be accurate and practical, it could offer a cheap, non-invasive solution for widespread COVID-19 testing to warn us of future outbreaks.

Scientists have found SARS2 (the virus that causes COVID-19) in stool samples of infected patients. Contaminated feces has been a concern in the developing world where sewage water can contaminate local water supplies. But in the US, water supplies are safe because they are regularly tested and chlorinated to clean it of infectious organisms.

Coronavirus in feces poses a risk for parents or caregivers changing diapers. This is one of the reasons why health agencies have stressed the need for hand-washing and personal hygiene. Thankfully, there have not been any confirmed cases of COVID-19 infection from feces.

SARS2 virus doesn’t survive long in feces or in the sewers, quickly breaking up into non-infectious proteins. But it’s RNA signature can be detected in sewer water samples, using highly sensitive PCR tests (Polymerase chain reaction). Because people defecate each day, this could allow real-time (or poop time) data to identify the start of new Covid-19 outbreaks.

Researchers in Paris sampled water from 5 Paris-area sewage plants. Between March 5 and April 7, they noted high concentrations of SARS2 RNA, days before the first recorded COVID-19 death in Paris. Concentrations continued to rise in the following days, matching a similar curve of COVID-19 cases in Paris. By sampling wastewater from different locations along the sewage lines, it’s theoretically to identify the regions of a city where outbreak clusters are occurring.

Epidemiologists know from past pandemics that infections come in waves. Communities that avoided the epidemic by isolating themselves, later become infected by visitors from fresh hot-zones. As states and countries see their COVID-19 numbers declining, they have begun to reopen business and schools, potentially leaving them vulnerable to a second wave of infection.

The only way to stop follow-up waves from taking hold is to isolate these new infection clusters. But that requires testing to identify them. Currently the way we test people for COVID-19 is through a painful process of inserting a long cotton swab into a person’s nose and swabbing the back of their nasal cavity for a mucus sample. These nose swabs are put through PCR testing machines that identify SARS2 RNA.

People don’t usually get tested unless they experience symptoms. The trouble is that many people are asymptomatic or only experience mild symptoms that could be masked by other conditions such as seasonal allergies. That means a large portion of the infected population isn’t being identified, making detecting a potential 2nd wave that much harder.

In other countries, voluntary (or in some countries mandatory) testing of healthy individuals has been conducted to detect for COVID-19 outbreaks. In the US, Public Health Officials have been considering the challenges of similar measures here. But people aren’t likely to voluntarily undergo painful nasal swabs unless they think they have been at risk. And mandatory testing would be a violation of civil rights and privacy.

Individual testing, whether voluntary or mandatory would be very costly as each test can cost as much as $300 each. And testing would need to be done regularly, in fact weekly, to be able to identify when new infections appeared. One could not overstate how expensive and difficult that would be in a city of millions of residents.

This is why the Paris study could be a game-changer. Even if a city tested dozens of sewer junctions, it would only cost a fraction of citywide individual human testing. Public Health Officials could in a sense, test millions of residents of a city connected to their sewer system at one go. When an uptick in virus RNA is detected, Public Health officials could mobilize resources to a district where the wastewater originated. Officials could deploy randomized or targeted testing, track-and-trace, and other measures to identify and quarantine the newly infected. This is how new outbreak waves can be stopped before they get out of control.

As we move past the peak phase of COVID-19 in the US, we must enter into a phase of peak COVID-19 vigilance. We need innovative ideas like this sewage test to give us an early warning. We need to know when and where the next outbreak wave happens, before the shit hits the fan.


SOURCES

https://www.sciencemag.org/news/2020/04/coronavirus-found-paris-sewage-points-early-warning-system

https://www.nature.com/articles/s41591-020-0869-5

https://www.medpagetoday.com/infectiousdisease/covid19/85315

Early Finding Covid-19 in stool were published in Scientific Journals as early as February https://doi.org/10.1056/NEJMoa2002032

Drinking Water is safe https://www.cdc.gov/coronavirus/2019-ncov/php/water.html

Fecal Oral transmission (important to wash hands when changing diapers) https://www.nature.com/articles/s41575-020-0295-7

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