Marseille, France, can predict COVID-19 spikes from shit in sewers
- Firefighters in Marseille, France, are fighting COVID-19 by testing wastewater.
- Officials told Insider the technique could detect outbreaks up to 6 days before they happen
- The technique is also fast, precise and relatively inexpensive.
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A team of French firefighters said they could prevent COVID-19 outbreaks in their city by analyzing particles of human excreta that end up in sewers.
Each week, heat maps of the city of Marseille appear on the Twitter account of the Marseille Fire Brigade Battalion (BMPM), a fire brigade led by the French Navy in the city.
—Marins-Pompiers de Marseille (@MarinsPompiers) March 17, 2021
In this tweet, the map in shades from green to red shows the distribution of the virus in different areas of the city.
The maps with shades of blue and brown show the distribution of the variants.
Since March 2020, the BMPM has been closely monitoring the spread of COVID-19 by sampling wastewater.
They take advantage of the fact that the coronavirus that causes COVID-19 can be detected in poop after infection.
Tests like this offer advantages over other methods: they are fast, require relatively few resources, and give an overview of a large area with just one test.
A BMPM official told Insider that sewage testing can detect clusters of COVID-19 four to six days before people start to experience symptoms.
Compared to the vast resources devoted to COVID-19 responses around the world, the technique is also inexpensive.
Officials told Insider that installation costs, even for a large city, would be in the range of $ 120,000, with ongoing costs as low as $ 50 per day.
Every Wednesday, in the wee hours of waking up, vans stamped with the name “COMETE” (expertise in Covid Marseille environmental tests) leave to collect wastewater samples.
These are collected at 37 different nodes where the wastewater for each district is located. They also monitor the water in places where populations are vulnerable, such as nursing homes, and take a sample every day for the entire city.
Firefighters take all their equipment with them into the neighborhood. It fits in a box the size of a large suitcase and can be transported in the van.
The water is analyzed with a PCR test, the same type of technology used for nasal swabs from people.
The results show if there are traces of the coronavirus in the wastewater samples, how strong the signal is, and what variants are in the mixture.
In less than an hour, the firefighters get their first results. And they are ready to take action.
If a signal is detected “we put all our energy in this neighborhood,” Rear Admiral Patrick Augier, commander of the BMPM, told Insider.
If levels rise in the city’s water, they are warning local authorities to anticipate new cases.
If the signal was found in the water of a building, everyone in that building is being tested quickly to find who could be carrying the virus and to isolate them.
Augier says he can detect if a person is carrying the virus outside of a building of 200 people.
A team also disinfects buildings and tests surfaces for traces of the virus.
In case of variants, the BMPM can identify in which building the person carrying the virus could be located.
Firefighters are testing surfaces for traces of the virus to help them determine which floor of the building the variant is on and are asking everyone on that floor to get tested.
According to an analysis by the BMPM, the technique was more than 90% effective in detecting a cluster of cases.
According to Augier, “when the virus circulates widely, we can do about thirty interventions per day”.
He equates his team’s response to some kind of war.
“You have to go very, very fast,” he says. “The virus is always one step ahead, it makes variations, it changes its behavior …”
“In this war, I would like us to be able to fully anticipate the situation,” he said.
Wastewater monitoring is not a new area. It has been used to track polio, cholera and even opioid use in a community.
“A lot of people would be squeamish, but I find wastewater really fascinating. There’s a lot of biology, chemistry, physical and chemical processes,” Colleen Naughton, associate professor of environmental engineering at UC Merced, told Insider.
It has been in use for decades but “has just exploded now, along with SARS-CoV-2,” she said, using the scientific name for the coronavirus.
Alexandre Lacoste, technical director of the brigade’s COMETE project, told Insider in an email that “the technique is like a radar that allows people to be tested en masse.”
Depending on where the water is collected, the sample can monitor an entire city, such as the greater Marseille region which has over a million inhabitants, or a single building.
It also offers a broader view of the situation than swab testing, which usually only happens after a person has developed symptoms. Some people may also not be able to get tested, for example undocumented migrants who might not want to take the risk of being discovered.
The University of California at San Diego runs a similar program. Smruthi Karthikeyan, a postdoctoral researcher there, told Insider: “Wastewater is kind of agnostic that way.
“You are going to pick up [COVID-19 signals] whether a person is still asymptomatic or presymptomatic and whether or not they end up getting tested. If they throw it in their stool, you’re going to see it. “