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A team of researchers from ETH Lausanne (EPFL) and ETH Zurich’s water research institute (Eawag) found coronavirus in sewage samples. They are now working on optimizing the method, it says in an ETH communication Thursday. According to the researchers, if the samples are analyzed quickly, a recurrence of infections could be detected during the release of the blockade approximately a week earlier than by clinical tests with those affected.
The first samples of wastewater from Lugano, Lausanne and Zurich were analyzed, in the case of Zurich and Lugano, also one of each at the end of February with the first known cases of infections in Switzerland. The researchers managed to detect the new coronavirus in all samples.
Conclusions on diffusion.
In the newer samples, the concentrations are so high that the analysis seems relatively easy. Not so for the February samples: “We could not hope that it would be possible to measure a signal in the Lugano wastewater with only one known case and from Zurich with only six known cases,” EPFL environmental scientist Tamar Kohn said in the message. . aforementioned
Based on the current state of knowledge, there is no evidence that the pathogen spreads through water or sewage. Swiss drinking water is of excellent hygienic quality and is also suitable for drinking during a pandemic, according to the report.
Successful detection of low virus concentrations early in the outbreak should allow retrospective reconstruction of the Covid 19 augmentation curve. However, it would still be weeks before the more than 300 samples currently stored at Eawag and EPFL are frozen.
However, it is difficult to infer an exact number of infected people, among other things, the number of viruses excreted by infected fluctuates too much. However, the course is important: Using samples from Lausanne as an example, scientists have been able to roughly trace the increase in Sars-CoV2 viruses in wastewater between March and April: Kohn currently estimates that the concentration has multiplied by ten and a hundred times.
Early warning system as main objective
Samples have been taken from twelve wastewater treatment plants, nine of them from Ticino, since the first Covid 19 diseases were known. However, the main objective of the project is not to look back, but to configure a system with a early warning function.
With samples from twenty large wastewater treatment plants that are geographically well distributed in Switzerland, the wastewater of around 2.5 million people can be monitored in this way, the ETH write. There are more than 700 wastewater treatment plants in Switzerland that clean around 1.7 billion cubic meters of wastewater.
According to the Federal Environment Office (Bafu), contagion with the coronavirus by contact with sewage is very unlikely, as was said in mid-April. According to Bafu, the contagion also seems unlikely due to skin contact with the river and seawater, as coronaviruses only survive in water for a short time and are effectively removed in wastewater treatment plants.
According to the announcement, research projects at this scale usually take several years. The group around Kohn (EPFL’s environmental chemistry lab), as well as Christoph Ort and Tim Julian of Eawag showed in a few weeks that the idea could come true. (SDA)
