« ABefore, we read in coffee grounds, now we read in people’s stools ”, laughs Alexandre Lacoste. A chemical engineer, this marine firefighter has been coordinating the Comete project (Covid Marseille Environmental Testing Expertise) for four months in the Marseille city. In his mouth, the method seems to be of the greatest simplicity. « Every day, we lift manholes at strategic points and we test the water that we take there “, he sums up. After compiling the results, the battalion draws up and publishes a weekly map of the city’s neighborhoods, classified according to the levels of concentration of the virus they find there.
On the Twitter account of the firefighters, the last map published indicates neighborhoods with more or less high levels of vigilance, as well as eight retirement homes and six schools tested positive. Unlike studies conducted by the national Obépine network across France, the city of 1.6 million inhabitants conducts its research at a local, even ultralocal, level.
Precise information …
The data collected would make it possible to estimate the extent of the prevalence of the virus at the level of a district, a school or an nursing home and to target the actions of the health authorities. « We can draw up a very precise map of the extent of the virus on Marseille territory and prioritize surface and human tests there ”, said the Deputy Mayor in charge of security, Yannick Ohanessian.
The marine firefighters follow the waters of a hundred strategic points, distributed throughout the city.
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In nursing homes, analyzes make it possible to detect contamination earlier than individual screening operations. “An infected and asymptomatic person sheds the virus in their stool. If she waits for the onset of symptoms to be tested, she has already infected around her ”, specifies Alexandre Lacoste. By monitoring the evolution of the situation in each establishment, the soldiers have already prevented the virus from spreading in certain places. Their level of precision would make it possible to detect the seropositivity of one person in a hundred. « When you find the virus in the water of a nursing home, you test everyone and isolate the positive case. In general it works ”, assures the firefighter.
… and precious
Since the port city is under the threat of the new English variant at the beginning of January, the control measures have developed and intensified. As soon as a potential cluster affected by the mutant virus is reported, the marine firefighters deploy to the areas concerned to test the wastewater, the inhabitants, but also the surfaces, a method praised by the battalion since the first wave.
For the regional health agency (ARS), these techniques provide valuable information for organizing action in the field. « The contributions of these new detection methods are a very interesting index of the evolution of viral circulation, which usefully complements the arsenal of indicators ”, specifies the agency of Provence-Alpes-Côte d’Azur. A week after the new variant was reported in Marseille, the ARS declared the epidemic focus « under control and under control ”. It is in particular thanks to the monitoring of wastewater that the city intends to follow the evolution of the variant on its territory. Monitoring conditional on the existence of sufficient means to be able to “sequence” the virus and detect the genomes of new variants.
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