Report by : Gan Yung Chyan
/ KUCINTA SETIA
The School of Environmental Hygiene has developed a set of methods for sampling and testing sewage, and understands the spread of coronary disease from the content of viral genetic material in sewage. Such monitoring can help target affected communities and conduct swab testing.
When the number of covid cases in the dormitories of foreign workers in Singapore climbed at the end of the month, SARS-CoV-2 could be detected in the sewage of the water supply recycling plants and dormitories. The National Environment Agency has launched a pilot program to understand the spread situation of covid by examining the content of viral genetic material in sewage.
The National Environment Agency, the Bureau of Internal Affairs, Science and Technology, and the Public Utilities Bureau issued a joint statement on 19 June 2020 that sewage monitoring is likely to become a way to assess covid outbreaks, because infected people will still have symptoms even if the symptoms are mild or asymptomatic as feces excrete viruses.
Since February 2020, the scientific staff of the School of Environmental Hygiene of the Environment Bureau has developed a set of wastewater treatment projects' sampling and inspection methods based on scientific advice from the Singapore Environmental Bioengineering Center (SCELSE), the Singapore-MIT Research Center (SMART) and the National University of Singapore.
With the support of the Internal Affairs Science and Technology Bureau and the Public Utilities Bureau, the scientific team collected wastewater from water supply recycling plants and guest quarters, and used sensitive molecular testing techniques in the laboratory to test samples and confirm the genetic material of SARS-CoV-2.
The sewage test results of the water supply recycling plant showed that as of 9 March, when there were 160 cases of covid in the country, the level of ribonucleic acid (RNA) in the sewage could not be detected but by the end of March, the viral genetic material in the sewage had risen to a detectable level, which coincided with the increase in the number of cases in the guest dormitory, proving that the results of sewage monitoring may even be used as a coronary disease early warning system.
The discovery prompted the authorities to conduct more swab tests on dormitory guest workers, and was able to identify and isolate more cases, including those with asymptomatic infections. This also makes the detection strategy more targeted and helps reduce the possibility of further spread.
In addition, the National Environment Agency has tested the sewage in 20 large dormitory manholes through a test plan, providing the authorities with an additional indicator in addition to swab testing to assess the dormitory outbreak and determine the adopted Does the measure work?
In a dormitory with no new cases, if the viral genetic material content in the sewage is also zero, the authorities can determine that there is no longer virus transmission in the dormitory and allow guest workers to leave the dormitory to work. The scientific team also found that the viral genetic material content in the sewage is related to the rate of virus transmission in the dormitory.
Sewage samples can also capture information from specific communities. For example, if the virus genetic material is detected in the sewage of a place, the authorities may conduct swab testing for the affected communities. More research is needed in this regard to understand whether the method will work in the early stages of infection or when there are few cases.
The notice pointed out that despite the potential, research on detecting the spread of SARS-CoV-2 by monitoring sewage is still in its early stages. The Environmental Bureau is collecting samples from more sewage nodes to improve the ability to detect coronaviruses.
The authorities also emphasized that the detection of viral genetic material in sewage does not mean that it is an active or infectious virus, because the coronavirus cannot be transmitted through sewage without a host.
As an additional precautionary measure, in places with coronary disease cases, such as hospitals, isolation facilities and guest dormitory, the sewage will also be disinfected with chlorine before being discharged into the public sewer, and chlorine can effectively eliminate viruses.
Source : Lianhe Zaobao
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