Turning Wastewater Into Insights

The testing of sewage and waste water could represent a powerful form of bio-surveillance, writes AMILI CEO Jeremy Lim.

AsianScientist (Jul. 8, 2020) – How much the world has changed in just a few months! From the declaration of a global pandemic on March 11, 2020, through to lockdowns in many parts of the world affecting billions of people, the world has learnt first-hand how much devastation a tiny virus can wreck on our lives and livelihoods.

Our realization that SARS-CoV-2, the causative microbe behind COVID-19, can be transmitted by asymptomatic individuals is particularly challenging for classical public health control measures of identifying and isolating cases before they can infect others. Hence, scientific attention has focused on the identification of asymptomatic cases and locking down of ‘hot spots’ preemptively before uncontrolled community spread.

Recent attention has turned to the testing of sewage and waste water, and this could be an exciting, novel form of bio-surveillance.


New wine in an old bottle?

What exactly is sewage surveillance? Sewage surveillance is the monitoring of wastewater from sewage systems to check for water-borne pathogens that could potentially cause disease. This is not novel and public health agencies have done this for decades.

In Singapore, the National Environmental Agency conducts regular screenings of the waterways that lead to public drinking water, recreational facilities and beaches, as well as industrial discharges, to ensure that any effluent coming from the waterways will not pose a risk of contamination to the rest of the sewage systems and waterways. Examples of commonly screened pathogens are E. coli species, Cryptosporidium, Giardia lamblia, rotavirus and norovirus, which are all emerging waterborne pathogens.

We know that SARS-CoV-2 is shed in human stool and this may be a route of transmission. In addition, this shedding may persist beyond the respiratory tract. In the light of these findings, several countries have commenced research to detect SARS-CoV-2 within wastewaters.

Both Australia and the Netherlands have shown that an increase in the number of COVID-19 cases is related to an increase in SARS-CoV-2 levels detected in wastewater discharged from affected communities, providing an important scientific proof of concept for sewage bio-surveillance. Singapore is following suit, although results have not been publicly announced.


Sewage bio-surveillance in the molecular age

Next-generation sequencing has greatly enhanced and enabled sewage bio-surveillance, allowing for comprehensive and diverse bacterial profiles to be generated more quickly. These profiles effectively serve as baseline pathogenic profiles which can be tracked over time, and any minute changes flagged for further study. Public health authorities could pre-emptively impose movement restrictions while investigations are carried out, potentially saving countries from much wider and even nationwide lockdowns.

This is currently still speculative, but could sewage profiles also be compared against the gut microbiome profiles of residents in local communities? Incongruencies could serve as markers for public health authorities to look at more deeply and ascertain whether there are novel pathogens emerging and spreading silently.

In the COVID-19 pandemic, could such techniques transform transport and enable our skies and waterways to be re-opened with more assurance? In 2018, six cruise ships that docked at Singapore’s ports had their ballast waters tested to determine if the water discharged from the ships met proposed D-2 Ballast Water Management Convention guidelines.

Two of these ships did not meet the standards and authorities could then determine what corrective measures were needed. Could this concept be adopted to test planes upon arrival? Could a point-of-care diagnostic be developed that gives a positive or negative result in minutes?

Imagine how this technique could help in easing quarantine restrictions! If a plane were arriving from a low risk country, passengers had no exposure history and the point-of-care diagnostic result was negative, could everyone then be allowed to whiz through health checks? And maybe coming home through our much vaunted Changi Airport, we could be in our beds an hour from ‘wheels down’?

The technology for point-of-care PCR panels already exists. US FDA-approved kits using multiplex PCR are available and can be used to test within an hour for pathogens as diverse as Clostridium difficile, Salmonella, Vibrio cholerae and rotavirus. AMILI already tests donor stool extensively for our Fecal Microbiota Transplant program and adding SARS-CoV-2 would definitely fall within the realm of possibility. Stay tuned!


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Copyright: Asian Scientist Magazine; Photo: Eliobed Suarez/Unsplash.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Jeremy Lim is co-founder and CEO of AMILI, the region’s first full-service gut microbiome company. He is also co-director of the global health program at the National University of Singapore’s Saw Swee Hock School of Public Health.

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