Neucrad Health April 27, 2020
The world is fighting an unprecedented battle against a virus. Yes, the COVID-19 outbreak has held almost the entire globe at hostage. Several countries are now practising social distancing and complete lockdown in a bid to arrest the spread of the pandemic. In such a scenario, if researchers provide an early warning system, then it would help in controlling a second wave of the medical emergency. An interesting yet cost-effective means of tracking the COVID-19 infection curve is through sewage sampling.
What is Sewage Sampling?
Sewers, in all big cities, continually collect human excreta, including their faeces and urine. It can provide real-time data about the viral load among the population. Sébastien Wurtzer, an eminent virologist at Eau de Paris (public water utility department of Paris), studied the presence of SARS-CoV-2 virus in the sewage of Greater Paris for over a month. He found a striking similarity of the viral concentration in wastewater to the shape of the COVID-19 pandemic. If this hypothesis works out, then it would be successful in warning about future outbreaks.
The unique technique applied by the group of researchers can detect a sharp increase in the viral load in sewage water even before cases explode in the city. It can act as an economical and non-invasive tool in predicting future waves of the epidemic. Wurtzer and his fellow researchers have posted the study on medRxiv on April 17th . However, it is yet to be peer-reviewed by other eminent scientists. Currently, the research is still at the preprint repository of medRxiv.
How does SARS-CoV-2 virus study in the sewage help in predicting future outbreaks?
According to recent studies on the SARS-CoV-2 virus, once the pathogen comes out of human bodies through faeces and urine, it starts degrading within a short time. However, scientists, have detected traces of the novel coronavirus even in the excreta of the human beings in sewage water. When researchers conduct polymerase chain reaction on the samples collected from the sewage water, they can obtain fragments of RNA of SARS-CoV-2 virus. Higher concentration of RNA in the sewage water may be correlated with higher number of infected people.
How did Wurtzer and his team sample sewage water?
Wurtzer and his fellow researchers started sampling sewage water from five localities in Paris twice a week between March 5th, 2020 to April 7th 2020. Their analysis revealed that a high concatenation of SARS-CoV-2 virus in wastewater before March 10th. It was the same time when Paris witnessed a spike in COVID-19 death. Studies also suggest that the increase in the viral load become noticeable a few days before the acceleration in clinical cases.
Laurent Moulin, a notable microbiologist and co-author in the study, opined that it takes about half a day to around three days for the sewage to get transported from the society to the treatment plants. Sewer sampling can act as an inexpensive evidence-based computer modelling of the progress of the COVID-19 curve. It can be extremely beneficial in developing countries, where individual tests can be a costly affair. Now, researchers can also provide a fair estimate of the number of infections in a catchment area by studying viral concentration in sewage. Zhugen Yang, another biomedical engineer at Cranfield University’s Water Science Institute, also opined that sewer monitoring could predict the timing and scale of the epidemic. They are also trying to develop a $2 test for analysing wastewater.
This was all about the sampling of sewers for tracking the COVID-19 infection curve. If scientists become successfully in designing this model, then it can act as an early warning in predicting the second wave of infections.