Combined sewer systems, flooding and COVID-19 - and transmission via the fecal-oral route?

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  • arno
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Combined sewer systems, flooding and COVID-19

Combined sewer systems (CSS) go back to the mid-1800s. And many of our older cities around the world still have these systems installed. They are particularly sensitive to periods of high precipitation and flooding. This is a very brief compendium from 15 minutes of Google searches that should wake up a sleeping world when it comes to this issue - the threat of COVID-19, climate change and the ancient CSS systems under many of our cities. 

Wastewater test could provide early warning of COVID-19
www.sciencedaily.com/releases/2020/03/200331092713.htm
www.dutchwatersector.com/news/sewage-wat...preading-of-covid-19

Dysfunctional sewer systems in flooded areas
www.theguardian.com/cities/2018/mar/21/p...ion-bangladesh#img-3

Concerns raised over sewage spreading virus into rivers
www.newcivilengineer.com/latest/covid-19...ng-virus-27-03-2020/

To understand coronavirus transmission, we have to understand our wastewater
www.theglobeandmail.com/opinion/article-...e-to-understand-our/

A Screening Assessment Of The Potential Impacts Of Climate Change On Combined Sewer Overflow (CSO) Mitigation In The Great Lakes And New England Regions (Final Report)
ofmpub.epa.gov/eims/eimscomm.getfile?p_download_id=472009

Combined Sewer Systems: Down, Dirty, and Out of Date
ehp.niehs.nih.gov/doi/10.1289/ehp.113-a464

Global monitoring of antimicrobial resistance based on metagenomics analyses of urban sewage
www.nature.com/articles/s41467-019-08853-3


The Water Professional’s Guide to COVID-19

www.wef.org/news-hub/wef-news/the-water-...9-novel-coronavirus/

AND

In doing this search I also discovered that the sewer systems (incl toilets, pipes and pumps) may experience blockages due to overloading with toilet paper or the use of newspaper and plastic wipes due to toilet paper shortages - all during this time of personal behaviour change.
See:
www.chinadaily.com.cn/a/202003/18/WS5e71...31012821727fed5.html
www.nytimes.com/2020/04/01/style/toilet-...ronavirus-wipes.html  
www.bbc.com/news/uk-england-tyne-51980820
communityimpact.com/dallas-fort-worth/co...-flushable-products/

The trusted sanitation and sewer systems that we rely on everyday can therefore act up and become a significant source of COVID inoculum may it be due to overloading, blockage or overflows. If these systems were to be partially and/or temporarily shut down by authorities before a vaccine becomes available, the impacts on further spreading could become debilitating. Urban open defecation in parks could become rampant before onsite pit facilities could be built. Especially the over-urbanised coastal mega-cities will be heavily taxed due to lack of green areas prompting mass evacuation. Hope this just remains a bad nightmare. But the indicators are all there........

Regards 
Arno Rosemarin PhD
Stockholm Environment Institute
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  • Elisabeth
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Re: Combined sewer systems, flooding and COVID-19

There might be all sorts of downsides to combined sewer systems (and also to sewer systems in general), particular in low-resource settings, but I think the risk of combined sewer systems spreading COVID-19 is pretty low compared to other transmission paths.

I looked at most of the papers that you linked to and they all seem to say that while there is a theoretical possibility, the risk of disease transmission for COVID-19 via sewage or stormwater overflow is currently assessed as low.

One of the articles that you linked to (To understand coronavirus transmission, we have to understand our wastewater
https://www.theglobeandmail.com/opinion/article-to-understand-covid-19-transmission-we-have-to-understand-our/ ) ended with this which I think sums it up well:

Given what little is known about how the new coronavirus might be transmitted in integrated water and wastewater systems or surfaces, additional research is desperately needed. In the meantime, lower the toilet lid when you flush, wash your hands with soap, don’t touch your face, and thank your municipal water and wastewater professionals for everything they do to keep us safe and healthy.

Probably the bigger problem areas (sanitation related) at present for developing countries are those areas that have no sanitation system at all and don't allow "social distancing" due to crowded living conditions and many people sharing one toilet etc.

Regards,
Elisabeth
Head moderator of this Discussion Forum
(under consultancy contract with Skat Foundation funded by WSSCC)

Dr. Elisabeth von Muench
Independent consultant located in Brisbane, Australia
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Founder of WikiProject Sanitation: en.wikipedia.org/wiki/Wikipedia:WikiProject_Sanitation
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  • arno
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Re: Combined sewer systems, flooding and COVID-19

Yes it looks like the corona virus may not persist in the sewage environment with all the chemicals we add from washing machines, dishwashers and cleaning compounds. However work from China during the SARS outbreak https://www.ncbi.nlm.nih.gov/pubmed/16312970  reported the following: 

"In this study, we found that the virus can survive for 14 days in sewage at 4 degrees C, 2 days at 20 degrees C, and its RNA can be detected for 8 days though the virus had been inactivated."

This report  https://theconversation.com/we-dont-know-for-sure-if-coronavirus-can-spread-through-poo-but-its-possible-135305
states that most of the body's sites for Corona virus attachment (the so-called ACE2 receptors) are found in the ileum (small intestine) and gastro-intestinal symptoms may be more common than earlier assumed. 

This study originating from China  https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmv.25825  indicates a ca 6-10 day period of viral shedding in 65% of cases after pharyngeal swab tests were negative.  They advise that transmission via the fecal-oral route be seriously considered.

Although the sewage environment may be toxic to the virus, bedpan routines in hospitals, onsite faecal sludge systems and container-based systems are worth monitoring - especially when examining risks to workers emptying these systems.

Regards 
Arno Rosemarin PhD
Stockholm Environment Institute
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