Given that most Indians are unlikely to be tested forCOVID-19, scientists are taking a cue from the country’s surveillance programmefor polio and turning to sewage to get a clearer snapshot of how many peopleare infected with the coronavirus.
Wastewater epidemiology is a valuable tool to monitor thespread of the novel coronavirus in communities, said Manish Kumar of the IndianInstitute of Technology in Gandhinagar who is working with an internationalteam of collaborators on the project.
The wastewater-based epidemiology (WBE) global collaborationcomprises over 50 institutes and researchers headed by Kyle James Bibby of theUniversity of Notre Dame in the US.
The group is coordinating sampling and analytical protocolsas well as data-sharing so that results obtained can be compared on a globalscale.
The numbers in India tell their own story a population of1.3 billion vs 9,02,654 tests till Friday, according to the Indian Council ofMedical Research. Over the last five days, India has been averaging 49,800tests a day.
The number of tests have almost doubled in the last eightdays — India had conducted just about five lakh tests from March 23 to April22 but this is still not enough to gauge the spread of the disease.
The current testing method is not enough to tell the exactsituation of the coronavirus infection in India. Even if the people showsymptoms for novel coronavirus,it will take three to 15 days actually to detectit, Kumar, assistant professor at the Department of Earth Sciences, told PTI.
That is too late. That’s why we thought, how aboutwastewater epidemiology, using wastewater to check if there is coronavirusgenetic material or not, said Kumar.
He said India’s polio monitoring system, which uses asimilar surveillance method, could come handy in the fight against coronavirus.
Sewage-based epidemiology is an indication of what may bemissed by case- based surveillance,GagandeepKang, executive director of theTranslational Health Science and Technology Institute, Faridabad, told PTI.
Kang agreed that the approach can be employed like poliosurveillance in the country.
According to Masaki Kitajima, a world renowned environmentalvirologist from Japan’s Hokkaido University, the presence of genetic materialof novel coronavirus provides an opportunity to use wastewater as asurveillance tool for the invasion, prevalence, molecular epidemiology, andpotential eradication of the virus in a community”.
The magnitude of COVID-19 spread is such that it provides usan opportunity for interdisciplinary coordination on a global scale to multiplythe impacts of individual efforts. Kumar’s team at IITGN has been a key memberin this effort, Kitajima,lead author of one of the first review papers on novelcoronavirus in wastewater, told PTI.
It is a published fact thatifsomebody is infected with thenovel coronavirus, they will excrete it through their body, in the form offaeces and urine, which in turn can be detected in wastewater, Kumar added.
We are not going to detect the live coronavirus inwastewater but their RNA (genetic material in viruses) present in sewage water.This collected sample will then be used in gene sequencing to assess how muchgenetic material of coronavirus is available, he said.
Kumar explained that the results can then be extrapolatedfor a genetic material estimation of the wastewater and assigned with aprobable number of people infected in a given locality or community.
I have sent the protocol to several institutes in India likein IIT Chennai, IIT Roorkee, IIT Guwahati and JNU Delhi, so we all can dosampling following one protocol, he noted.
He added that the Gujarat Pollution Control Board (GPCB) andGujarat State Biotechnology Mission (GSBTM) are providing his team all thecooperation to accomplish the work.
Several preliminary studies have reported the detection ofSARS-CoV-2 RNA in wastewater in the early stages of local outbreaks whichfurther supports the relevance of WBE, said WBE head Bibby.
We can determine the burden of undiagnosed infections at thepopulation level, which is critical to refining estimates of case-fatalityrates, he said.
According to Keisuke Kuroda from Japan’s Toyama PrefecturalUniversity, who is also a part of the collaboration, an accurate prediction ofinfected population by WBE will naturally involve multiple uncertainties, someof which will be linked with variousgeographic, climatic, demographic,socio-economic, and environmental conditions.
I believe that Kumar’s team will certainly provideconsiderable insights into WBE’s globalapplication, Kuroda,who has publishedseveral papers on the fate of viruses and pharmaceuticals in urban waters ofJapan and Vietnam, told PTI.
In a study published last week in the journalScience of theTotal Environment, researchershighlighted the economic advantages of theapproach over conventional disease testing and epidemiological surveillance.
“Our results show that exclusive reliance on testing ofindividuals is too slow, cost-prohibitive and in most places, impractical,given our current testing capacity,” saidRolf Halden, a professorat theArizona State University (ASU) in the US, who was a part of the research team.
“However, when preceded by population-wide screening ofwastewater, the task becomes less daunting and more manageable,” he said.
However, the research indicates that careful calibrationmust be carried out to ensure the accuracy of data, which is acutely sensitiveto key variables, including seasonal temperature, average in-sewer travel time,degradation rates of biomarkers, community demographics and per-person wateruse.
Estimates based on European and North American data suggestthat each person infected with SARS-CoV-2 will excrete millions if not billionsof viral genomes into wastewater per day.
This translates to between 0.15 and 141.5 million viralgenomes per litre of wastewater generated, the researchers said.
Usingreverse transcriptionPCR (RT-qPCR)–a laboratorytechnique of molecular biology–researchers should be able to detect the novelcoronavirus with high sensitivity, Kumar said.
Kumar said he has been contacted by the2030 Water ResourcesGroup of World Bank and several stakeholders in Maharashtra with whom WBE groupand his team are generously sharing the sampling and analytical protocol.
The coronavirus can only be defeated by unity, perseveranceand persistent efforts, he said.