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Table of Contents
PERSPECTIVE
Year : 2021  |  Volume : 7  |  Issue : 2  |  Page : 79-82

Whether COVID-19 has waterborne transmission too?


1 Department of Paediatrics and Neonatology, All India Institute of Medical Sciences, Patna, Bihar, India
2 Department of Biochemistry, Maharshi Devraha Baba Autonomous Medical College, Deoria, Uttar Pradesh, India

Date of Submission30-Jul-2021
Date of Acceptance08-Nov-2021
Date of Web Publication24-Dec-2021

Correspondence Address:
Dr. Chandra Mohan Kumar
Department of Paediatrics, All India Institute of Medical Sciences, Patna - 801 507, Bihar
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijcfm.ijcfm_60_21

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  Abstract 

SARS CoV-2 and COVID-19 have hogged the headlines for almost 18 months and over the last 2 months, it has occupied the mind space of entire India. Its second wave has not only sent shock waves across the nation but has created ripples across oceans too. There has been intense debate over how it went spiralling up in such a manner that India is is reporting large number of cases daily as well as deaths. One of most hotly debated topics is “Whether it is being transmitted through contaminated water too?” There is enough evidence that the virus sheds in feces and that the virus sheds in feces, sewage, sewer lines, waste water, and sewage treatment plants as well as effluents of plants. The important factor is that about two-third of sewer is not treated. On top of that, countries such as India do not have universal access to safe drinking water and practice of open defecation is still prevalent. In such a scenario, likelihood of waterborne transmission cannot be ruled out.

Keywords: Aerosol, contamination, coronavirus, safe drinking water, sewage treatment, transmission


How to cite this article:
Kumar CM, Chowdhry BK, Singh S. Whether COVID-19 has waterborne transmission too?. Indian J Community Fam Med 2021;7:79-82

How to cite this URL:
Kumar CM, Chowdhry BK, Singh S. Whether COVID-19 has waterborne transmission too?. Indian J Community Fam Med [serial online] 2021 [cited 2022 Jan 23];7:79-82. Available from: https://www.ijcfm.org/text.asp?2021/7/2/79/333665




  Introduction Top


SARS CoV-2 and COVID-19 which caused the biggest pandemic over a century has been an enigma too. From beginning, there was a great deal of uncertainty regarding it and that included its mode of transmission. Initially initially believed to be a fomite and droplet borne infection an later on evidence emerged and it was accepted to be transmitted through aerosols too.

On top of that, hotly debated topic is “Whether it is being transmitted through water too?”

There are four steps required for a disease to be transmitted through feco-oral route, i.e., drinking water:

  1. Shedding of the causative agents in feces
  2. Survival of the causative agents in feces/stool sample
  3. Presence of the causative agent in treated sewage.
  4. Presence of the causative agent in drinking water.


Exponentially increasing number of infections among persons not having direct person to person contact with infected persons, raises questions that whether droplets, fomites, and aerosols are only Initially? A strong degree of suspicion arises about some other route of transmission that can explain the rising number of cases among people not directly coming in contact. So the question arises that; is there is a waterborne community transmission too? As of today, WHO's position is that there is no evidence of it being transmitted through water and chances of transmission are low.[1] However, WHO or the scientific community at large has not completely denied the possibility of such transmission. Experts don't have the definite viewpoint on it, but the virus that causes COVID-19, the notorious SARS-CoV-2, does definitely have the potential to spread through untreated sewage. Many investigations including that by Zhang et al. have reported evidence of presence of viral RNA fragments of SARS-CoV-2 in the stool samples of infected patients.[2]

A study by Xiao et al. reported that among samples of feces of 73 hospitalized patients admitted with SARS-CoV-2, 53.4% of the cases had positive real-time reverse transcriptase-polymerase chain reaction on stool samples.[3]

Now the second question is whether the SARS-CoV-2 survives in stool? There is an evidence for that too. In SARS coronavirus study by Wang et al., there was evidence of a surrogate human coronavirus surviving for two days in dechlorinated tap water and in hospital wastewater at 20°C.[4]

Hence, if the coronavirus survives in stool as well as flushed waters, that water entering sewerage systems also becomes the potential mode of transmission for this virus. A study by Gundy et al. has demonstrated that coronaviruses survive up to 2–3 days in sewage water and up to 10 days in tap water at 23°C.[5] Currently, there is no evidence that SARS-CoV-2 can be transmitted by treated drinking water. The virus being an encapsulated microbe is sensitive to oxidants such as chlorine and gets quickly destroyed, but what about transmission through untreated water? In countries like India, the access to proper safe and hygienic drinking water is not universal. In addition, poor sanitation conditions and practices such as open defecation have the potential to further increase the chances of transmission by flies, fomites, or surface water contamination.

In India also, in 2020, the SARS-CoV-2 was isolated from hospital wastewater and sewage in Jaipur where two samples were identified containing viral genome.[6] Their analysis pointed toward a continuous increase and clustering of COVID-19 patients in the areas served by the waste water treatment plants from where wastewater samples had tested positive. However, there were no viral genomes found in treated water. Treatment of sewage reduces likelihood of transmission as the treated efflux has not been found to have virus.[6] However, in Tehran, Iran two samples from treated sewage were also found positive, making it again a controversial subject[7] and with current evidence, nothing can be concluded with conviction. Similar suspected transmission of SARS-CoV-2 in public bath in China has also been reported.[8]

As the SARS-CoV-2 virus RNA has been documented in fecal matter, waste today various countries at various stages and waves, it can be assumed that irrespective of virus variants in circulation, the waterborne transmissibility potential exists.

WASH Facilities in India- Status Check

In India, another big issue is the lack of adequate facility for sewage treatment. The sewage treatment plants in India are not adequate to handle the total sewage generated. Only 26,869 million liters per day (MLD) of sewage is treated, whereas the total generated sewage stands at 72,368 MLD, with releasing of 45,499 MLD (>62%) of sewage untreated to the water bodies and thus creating a huge risk for waterborne transmission.[9] The model showing status of sewage treatment facility, availability of safe drinking water, and the likely possibility of untreated sewage/water being able to contaminate water bodies and drinking water is given as pieces of Zigsaw puzzle in [Figure 1].
Figure 1: Model of waterborne SARS-CoV-2 transmission

Click here to view


This concern about safety of water is not new. In the United States of America also where potable water, sanitation and hygiene (WASH) facilities are universal, during 2020 surge, there was 57% increase in the consumption of bottled water compared to same period a year ahead.[10] Hence, it is evident that even though there has been no concrete evidence of transmission through drinking water, there has definitely been a concern and suspicion.

The Needle of Suspicion

Giving more credence to such likely transmission is the fact that around 10% of COVID-19 cases present with gastrointestinal (GI) symptoms and which precede systemic and respiratory symptoms, suggesting feco-oral route as most likely transmission. The incidence of GI presentation is more in children which is in line to the study by De Man et al., which showed children are 7–8 times more vulnerable to GI symptoms in cases of waterborne exposures compared to adults.[11] Noteworthy is that in a study by Xiao 23.29% of the patients with viral RNA untraceable in respiratory tracts showed the presence of SARS-CoV-2 in their feces.[3]

Hence, if we revisit the four prerequisites of feco-oral waterborne transmission mentioned above, first two have documentary evidence, whereas in India, 62% of sewage is disposed off untreated and 28% urban and 48% rural households do not have access to safe drinking water.[12] Hence, in light of above-mentioned facts in a country like India, the possibility of waterborne spread of COVID-19 cannot be ruled out. Another point which is baffling, is the continued transmission of COVID-19 in April − September, the summer and monsoon/postmonsoon months, which normally is the transmission season for enteric fever, diarrheal diseases, viral hepatitis, etc., the classical water borne diseases. Whereas the classical droplet/aerosol borne acute respiratory infections are usually transmitted in bimodal peak of October − November and February − March.

On close analysis of incidence data for COVID-19 in India, during April to September 2020, morethan 6.2 million cases were reported which were higher than 5.9 million reported between October 2020 and March 2021. Even number of mortalities due to COVID-19 followed the similar trend and summer months accounted for more deaths, 96,000 as compared to 96,000 in winter months.[13]


  Conclusion Top


Hence, going with the above-mentioned facts and studies, we can conclude that SARS-CoV-2 virus has been demonstrated to be present in stool of infected persons, sewage and has the potential of surviving in untreated water for sure. In countries with poor WASH facilities where untreated sewage is allowed to be discharged in water bodies and availability of safe drinking water is not universal, possibility of COVID-19 being transmitted as a waterborne infection cannot be ruled out. The jury is still out on whether COVID-19 has waterborne transmission.

Steps for Prevention of such Likely Transmission

In view of definitive evidence of presence of viral genome RNA in feces, urine, waste water, sewage, waste water treatment plant (WWTP) effluents, and likelihood of unsafe disposal of WWTP effluents leading to infection of water bodies and surface contamination, there is a need of revisiting WWTPs waste disposal policies as well as ensuring availability of safe drinking water in areas where sewage treatment facilities are not available. Various studies suggest that temperature treatment is the most effective way of destroying SARS-CoV-2 virus in WWTP effluents as increasing temperature denatures viral proteins and destroys enveloped viruses. Hospitals need to update their wastewater treatment systems and to use decentralized wastewater treatment systems so that viruses are not transmitted to the larger community. Ultraviolet-based portable devices for wastewater treatment, ensuring leakage free plumbing system, and ensuring residual chlorination of drinking water free of coronaviruses must get enough priority.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
2.
Zhang Y, Chen C, Zhu S, Shu C, Wang D, Song J, et al. Isolation of 2019-nCoV from a stool specimen of a laboratory-confirmed case of the coronavirus disease 2019 (COVID-19). China CDC Wkly 2020;2:123-4.  Back to cited text no. 2
    
3.
Xiao F, Tang M, Zheng X, Liu Y, Li X, Shan H. Evidence for gastrointestinal infection of SARS-CoV-2. Gastroenterology 2020;158:1831-3.e3.  Back to cited text no. 3
    
4.
Wang XW, Li JS, Jin M, Zhen B, Kong QX, Song N, et al. Study on the resistance of severe acute respiratory syndrome-associated coronavirus. J Virol Methods 2005;126:171-7.  Back to cited text no. 4
    
5.
Gundy PM, Gerba CP, Pepper IL. Survival of coronaviruses in water and wastewater. Food Environ Virol 2009;1:10.  Back to cited text no. 5
    
6.
7.
Nasseri S, Yavarian J, Baghani AN, Azad TM, Nejati A, Nabizadeh R, et al. The presence of SARS-CoV-2 in raw and treated wastewater in 3 cities of Iran: Tehran, Qom and Anzali during coronavirus disease 2019 (COVID-19) outbreak. J Environ Health Sci Eng 20211-12.  Back to cited text no. 7
    
8.
Luo C, Yao L, Zhang L, Yao M, Chen X, Wang Q, et al. Possible transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a public bath center in Huai'an, Jiangsu Province, China. JAMA Netw Open 2020;3:e204583.  Back to cited text no. 8
    
9.
National Status of Waste Water Generation & Treatment. ENVIS Centre on Hygiene, Sanitation, Sewage Treatment Systems and Technology. Available from: http://www.sulabhenvis.nic.in/Database/STST_wastewater_2090.aspx. [Last accessed on 2021 May 03].  Back to cited text no. 9
    
10.
11.
De Man H, van den Berg HH, Leenen EJ, Schijven JF, Schets FM, van der Vliet JC, et al. Quantitative assessment of infection risk from exposure to waterborne pathogens in urban floodwater. Water Res 2014;48:90-9.  Back to cited text no. 11
    
12.
Available from: https://www.indiawaterportal.org/article/everything-you-want-know-about-drinking-water. [Last accessed on 2021 May 03].  Back to cited text no. 12
    
13.
Available from: https://prsindia.org/covid-19/cases. [Last accessed on 2021 May 20].  Back to cited text no. 13
    


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