|LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 1 | Page : 35-36
COVID-19 in sewage: Implications in surveillance diagnosis and infection control
Rimjhim Kanaujia1, Manisha Biswal1, Archana Angrup1, PV M. Lakshmi2, Pallab Ray1, Arunaloke Chakrabarti1
1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Community Medicine, School of Public Health, Post Graduate Institute of Medical Education and Research, Chandigarh, India
|Date of Submission||19-Jul-2020|
|Date of Acceptance||21-Jun-2020|
|Date of Web Publication||4-Sep-2020|
Dr. Archana Angrup
Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kanaujia R, Biswal M, Angrup A, M. Lakshmi P V, Ray P, Chakrabarti A. COVID-19 in sewage: Implications in surveillance diagnosis and infection control. J Patient Saf Infect Control 2020;8:35-6
|How to cite this URL:|
Kanaujia R, Biswal M, Angrup A, M. Lakshmi P V, Ray P, Chakrabarti A. COVID-19 in sewage: Implications in surveillance diagnosis and infection control. J Patient Saf Infect Control [serial online] 2020 [cited 2020 Oct 21];8:35-6. Available from: https://www.jpsiconline.com/text.asp?2020/8/1/35/294371
The pandemic of COVID-19 is spanning across various continents with a number of concerns related to its spread. Although droplet transmission is the most common mode of the spread, extra respiratory routes may also help explain the rapid spread of the disease. One of the putative routes of transmission in the community could be faeco-oral route. This view has come from recent reports which show that SARS-CoV-2 has been detected in stool samples of COVID-19 patients presenting with diarrhoea. In some stool, samples of these patients high RNA copies and viable SARS-CoV-2 have been detected. Another critical concern is in children who mostly have asymptomatic infections and have a prolonged shedding of virus (8–20 days) even after respiratory samples have become negative. They may act as a silent source of infection and pose a threat to the community. SARS-CoV-2 can appear earlier in faeces i.e., <3 days of infection. This time period is much sooner than the time taken for patients to develop symptoms severe enough for them to seek hospital care. The shedding of SARS-CoV-2, studied in a cluster of nine patients was up to 107 RNA copies/g of faeces 1 week after symptom onset which decreased to 103 RNA copies/g after 2 more weeks. The flushing of the toilet can produce bio-aerosols and droplets containing live 2SARS-CoV-2. These small droplets (2 mm) can be of airborne infection concern. Furthermore, in a recent study in Australia untreated wastewater in a catchment area had two positive detection within a duration of 6 days and on Monte-Carlo simulation the estimated number of infected individual was in a reasonable agreement with the clinical findings. With most of the countries struggling to match the pace of the spread of disease vis-a-vis the limited number of diagnostic testing being done for the virus, an urgent requirement for alternative methods to detect the community spread of the disease is the need of the hour. Therefore, analysing the wastewater i.e., the used water that goes through the drainage system to a treatment facility - has been proposed as a method to track the spread of SARS-CoV-2 and locate hot spots. In addition, if bio-aerosols act as potent source of transmission, it will have implications in infection control, to prevent further spread to health-care workers and community.
Wastewater monitoring has been used since decades to assess the success of vaccination campaigns against poliovirus whose main mode of transmission is mainly by the faeco-oral route. The effectiveness of a vaccine campaign is assessed by the decline of virus strains from the sewage. The Netherlands National Institute for Public Health and the Environment in Bilthoven has also previously done extensive monitoring of sewage to detect the outbreaks of norovirus and poliovirus. According to a study from the Netherlands, one treatment plant could capture wastewater from more than one million people. Therefore, monitoring the wastewater for viruses may be one effective way to keep under surveillance of the dynamics of the disease. The detection of SARS-CoV-2 in sewage by regular surveillance can act as an early warning tool. Amersfoort was successful in reporting virus circulation in the community prior to the reporting of COVID-19 cases through the health surveillance system. This technique is non-invasive and can alert the authorities prior to the actual outbreak and effective intervention can be carried out. The testing of the sewage at regular interval can check the dynamics and provide a snapshot of the circulating viral RNA in the community. This will allow the authorities to intervene at an early stage to take stringent measures to contain the virus and also measure the effectiveness and success of the different infection control interventions., In low- and middle-income countries with poor sanitation faeco-oral transmission of COVID-19 might be more relevant. In these areas with limited diagnostic facilities, wastewater surveillance can be a precious source for data.
Various methods for the detection of the virus in wastewater such as reverse transcription and polymerase chain reaction (PCR) of nucleocapsid protein gene (N1-3) to detect the genetic material of SARS-CoV-2 and different surrogate markers have been used for the surveillance of viruses in wastewater. Furthermore, paper-based devices which integrate different steps for nucleic acid testing are available which are easy to store, stack and transport., In Beijing, Wang et al. utilised a novel method of concentrating SARS-CoV from the sewage by using a electropositive filter media particle. However, wastewater has impurities and has PCR inhibitors. Dilution of the sample may also limit the detection of viruses present in small quantities. The quantification of the infection in a population from wastewater samples requires knowledge about the amount of viral RNA excreted in faeces. This finding can be extrapolated on the population and number of patients infected can be detected. In addition, the infectious potential might not correlate with the detection of viral RNA in the sewage. This was found iIn a study from Beijing, where RNA of SARS-CoV-2 was detected in hospital sewage, both before and after disinfection, but no viable virus was detected.
Hospitals should take precautionary measures to avoid transmission of the virus through bio-aerosols by implementing strict hygiene. The caregivers should avoid direct contact with the faeces. Wherever feasible, the cover of the toilet seat should be closed before flushing. The sewage of the patients receiving SARS-CoV-2 should be disinfected and use of tertiary treated water in gardening, etc., should be avoided.
In conclusion, despite the technical challenges, monitoring sewage might be a potential tool to obtain a snapshot of the current spread in a community. This environmental testing may complement clinical surveillance and help to understand the transmission dynamics of COVID-19 from person to person through sewage.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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