What Bengaluru’s wastewater analysis by TIGS reveals about the current status of Covid-19

TIGS conducts wastewater surveillance, monitoring 26 Sewage Treatment Plants (STPs) in Bengaluru for the presence of the Covid-19 virus shed by individuals in various localities.

Recent data reveals that all 26 STPs have detected the presence of the virus.

#BangaloreEnvtSurvCOVIDUpdates

The city-wide Bangalore wastewater 𝗽𝗼𝘀𝗶𝘁𝗶𝘃𝗶𝘁𝘆 𝗿𝗮𝘁𝗲 for SARSCoV2 is around 𝟵𝟲% in the week, 22nd Jan – 25th Jan 2024 𝟭𝟬𝟬% in the week 29th Jan – 1st Feb 2024 across 26 STPs. pic.twitter.com/tyrD3N8yBs

— Tata Institute for Genetics and Society, India (@TIGS_India) February 7, 2024

Wastewater surveillance

During the most recent Covid wave, the sewage surveillance data acted as a harbinger, providing early indications of an impending surge in cases. At its peak, the sewage surveillance results indicated an average viral load exceeding 3,000 copies per ml.

However, the current data — from 29 January to 1 February — reveals a decline, with viral loads now in the hundreds. Notably, most STPs showed minimal viral loads during the peak, except for the Lalbagh STP, suggesting no anticipated wave-like situation in any specific area.

Since August 2021, when TIGS initiated wastewater surveillance, it consistently demonstrated a peak in viral loads before each Covid wave, establishing itself as a valuable method for predicting and tracking disease prevalence. As Dr Mishra emphatically puts it, “Everything eventually comes out through the sewage system.”

Viruses or pathogens enter wastewater through the stool of infected individuals. Scientists can test the STP samples for these viruses and pathogens.

“By testing, we know how many viral particles an infected person is shedding in a day. We also try to get the population size in the STP’s catchment area and estimate the RNA (ribonucleic acid) fragments of the virus in the sewage system,” Dr Mishra explains.

In Hyderabad, ICMR-CCMB conducts the wastewater surveillance.

#Realtime #SARSCoV2 viral load in sewershed sites #wastewaters and reported #COVIDー19 cases – the viral load shows a sharp decline.

There is no clinical testing data available since 8th November pic.twitter.com/SnBFVd2bZB

— Tata Institute for Genetics and Society, India (@TIGS_India) February 7, 2024

The technology at play

Wastewater surveillance is a crucial and cost-effective tool for monitoring population health, providing early warnings of disease spread. Infected individuals can shed the virus in their faeces, even without symptoms, making wastewater monitoring an effective means to capture the true presence of SARS-CoV-2.

Wastewater monitoring can inform public health responses and anchor global disease surveillance with just a glass of water from each STP.

Dr Mishra says that wastewater surveillance is a convenient way of knowing what is happening in a city, in terms of infection, medicine usage, drugs, etc.

“This helps in estimating the number of people shedding the virus. With this data, we can calculate the number of infected people in the catchment area on that particular day,” Mishra explains.

Wastewater monitoring can be an early indicator that the number of people with Covid in a community is increasing or decreasing, and it does not depend on people having access to healthcare, people seeking healthcare when sick, or availability of Covid testing.

Wastewater surveillance provides community-level data quickly and efficiently. Wastewater data can show changes in disease trends four to six days before the signs are reflected in clinical cases. A single wastewater sample captures the infection status of a population numbering thousands to millions of individuals.

Wastewater surveillance is not new. It has been carried out for a long time but on a smaller scale. “It gathered pace during the pandemic, and its benefit caught the attention of several civic agencies,” Mishra points out.

The technology’s success has led to its expansion, with plans to include multi-pathogen detection for a more comprehensive understanding of circulating pathogens. Dr Mishra’s team has been testing various pathogens, and the goal is to create a versatile system adaptable to monitoring various cities and safeguarding public health.

“We can detect various serotypes of dengue and tuberculosis. We even tried to track monkeypox, but it was not present,” he recalls.

“Environmental surveillance provides insights into real trends that may not be immediately apparent in the physical world. We plan to continue our Covid 19 surveillance for another year. This extended effort aims to establish a comprehensive surveillance system, encompassing a standardised operating procedure (SOP), locally developed technology, and a well-trained team,” Dr Mishra says.

He adds, “This system can subsequently be applied to monitor other pathogens such as avian or common flu, antimicrobial resistance (AMR), vector surveillance, etc. The goal is to create a versatile system that can be adapted for use in various cities to monitor sewage and safeguard public health.”

Also Read: Recent research shows how Covid decreases lung function even months after the infection

CrisprBits takes on wastewater surveillance

Currently employed by Molecular Solutions Care Health LLP, the test is actively engaged in weekly monitoring of the Omicron-derived JN.1 variant in sewage samples from 14 localities in Bengaluru, funded by Blockchain for Impact.

A recent comprehensive study, soon to be published in the Journal of Biotechnology and Biomedicine, validates OmiCrisp in 80 clinical samples and over 160 wastewater samples.

These clinical samples underwent cross-validation against the highly accurate next-generation sequencing platform, while wastewater results were compared using approved RTPCR tests. Impressively, the CRISPR-based test displayed remarkable resilience to poor-quality samples derived from sewage, showcasing its utility in identifying even single base changes in matrices of inferior stability. The study attests to an outstanding 99 percent accuracy in detecting the Omicron lineage in both clinical and wastewater samples.

In a statement, Professor Vijay Chandru, Chief Scientific Officer, and Co-founder of CrisprBits, highlighted, “OmiCrisp validation is one of the first studies to employ CRISPR-based testing in environmental samples.”

OmiCrisp’s development was a collaborative effort with C-CAMP-InDx (Indigenisation of Diagnostics programme anchored at C-CAMP). The validation on clinical samples received support from DBT-inStem biorepository and the Covid testing laboratory at Strand Life Sciences.

Also Read: Wastewater surveillance in Bengaluru shows sharp decline after recent spike