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fromClaudia Kabel
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Researchers evaluate samples from sewage treatment plants all over Germany. Darmstadt is also participating in the study by the Helmholtz Center for Environmental Research and the TU Dresden.
Many people are infected with Sars-CoV-2 but are not tested because they have no or no typical symptoms. Although they do not appear in the statistics, each time they go to the toilet they excrete the genetic material of the virus. Investigating this is the aim of a nationwide study that began in May 2020 and is currently being evaluated. The project is carried out by the Helmholtz Center for Environmental Research (UFZ) in Leipzig and the TU Dresden, supported by the German Association for Water Management, Sewage and Waste (DWA).
early warning system
The idea of wastewater monitoring is not new. Similar investigations were carried out as part of drug screening and in connection with polio vaccination measures.
With sampling At around 900 sewage treatment plants, around 80 percent of the total wastewater flow and thus a large part of the population in Germany could be recorded on a daily basis.
Up to the area-wide Monitoring system, there are still some challenges to be overcome. That is why the Helmholtz Center for Environmental Research and TU Dresden are working with the German Association for Water Management, Sewage and Waste to examine the approach under real conditions. cka
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According to the UFZ, the scientists assume that wastewater can primarily be used to detect virus mutations. The relative proportion of different mutations that occur in a catchment area could thus be assessed on the basis of a few samples. “The data is currently being analyzed – also with regard to the detection of virus mutations, which are playing an increasing role in the infection process,” says René Kallies, who heads the laboratory tests at the UFZ. One of the 50 sewage treatment plants in which samples were taken is the Darmstadt central sewage treatment plant. It “is becoming apparent that wastewater monitoring can serve as an early warning system that indicates a higher number of new infections at an early stage when the official incidence figures are still low,” says the city treasurer, André Schellenberg (CDU), who is responsible for wastewater management. After pilot tests, a six-week practical test began in October. For this purpose, the sewage treatment plants provided 24-hour composite samples and primary sludge five days a week.
The samples were processed in such a way that the viral gene strand, the RNA, can be extracted. Detection is then carried out by means of PCR. The discovery of mutations or virus variants in wastewater is quite time-consuming, says Kallies. This is because the samples contained comparatively small amounts of genetic material, which makes a more complex preparation of the samples necessary for sequencing. In contrast to patient material, wastewater could also contain many different genome variants. A clear assignment to the worrying virus variants is currently still problematic.
In another project, the Technical University (TU) Darmstadt is researching the corona early warning system for wastewater. Samples from Frankfurt and Frankfurt Airport were examined. One of the most interesting findings of this study so far is, according to Susanne Lackner, head of the TU wastewater management department, that “over half of the virus variants present have not yet been described or are not clinically relevant”.
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