Sewage water will be an even better indicator for early detection of corona outbreaks. As of this week, the RIVM sewer measurements have been adjusted in such a way that they can detect virus particles earlier and more accurately. The new measuring methods will be used from tomorrow the corona dashboard from the national government.
“We then show different figures”, says Ana Maria de Roda Husman, who leads the sewerage research at the RVIM. “Namely: how much virus is in the sewer, calculated per 100,000 inhabitants. Then the sewer measurements can better be compared with other indicators on the dashboard. Such as the number of positive people.”
Up to now, calculations per 100,000 inhabitants were not possible because only the water samples from more than three hundred test locations were analyzed without knowing how many households that water was. “This new addition makes it possible to look much more precisely where new outbreaks arise, even before people realize that they are ill. Then we can take much more targeted regional measures.”
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The RIVM researcher says that from now on it is also possible to measure the number of virus particles per milliliter of wastewater, without the amount of rainwater influencing this. That also makes the data more accurate.
In addition, RIVM will start taking samples twice a week this month. Now that is only once a week. “By measuring more often, it is possible to respond more quickly to regional increases.” In the future, RIVM wants to measure even more often “Three, four times a week or even daily.”
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At the beginning of September, we saw the values increase in the sewer measurements.
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The sewage research that De Roda Husman and her laboratory at RIVM has been doing since the start of the corona crisis is unique in the world. It soon turned out to be a good indicator for detecting corona. Even before people develop symptoms associated with corona, about 40 percent of infected people excrete more or less virus particles in the stool.
The RIVM researcher says that they saw the second wave arrive at the beginning of September. “Then the values for the sewer measurements increased.” According to her, the sewage water now presents a very varied picture. “In some locations the values are still rising but in other locations it seems to be decreasing.”
As of August, the number of test locations has been expanded to about 316 across the country. The results of the measurements can be found on the dashboard every week.
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Some people defecate more than others
At the Elizabeth Tweesteden Hospital in Tilburg, they have been involved in the RIVM’s sewage water research from the start. Microbiologist Jean Luc Murk and his team tap sewage water right next to the hospital. This clearly shows that the hospital is full of corona patients. It is therefore mandatory to keep a distance of 1.5 meters from the tap point because the virus particles come fresh from the hospital toilet.
With his research, Murk hopes to soon be able to determine how many virus particles one corona patient produces on average. “In this way we will not only be able to determine even better where the infections occur, but also how many people are involved.”
According to Murk, the study is “difficult because some people go to the toilet several times a day and therefore excrete virus particles several times a day. While others hardly do. Moreover, there are many bends in the sewer where excrement can get stuck, causing the results are not yet reliable. “
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