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Wastewater as a cheap and rapid surveillance tool for virus
Field testing before transportation of the sample
With Sri Lanka in the throes of the second wave of COVID-19, a multidisciplinary team in the hill town of Kandy has gone beyond their call of duty to bring about a simple solution to get a heads-up of an imminent infection so that it could be contained before the spread starts.
Poring over reams of scientific literature and wearing tight their thinking caps, they have come up with a novel concept – a ‘simple wastewater-based surveillance method’ for the rapid detection of the new coronavirus, SARS-CoV-2, at community level.
This wastewater-based surveillance method, which has seen the light of day, due to a strong collaboration between the National Institute of Fundamental Studies (NIFS) and the Kandy National Hospital, would help take away the burden on RT-PCR testingof nasopharyngeal samples. It would give an ‘early warning’ whether a high-risk group is having the infection, the Sunday Times understands.
With research done elsewhere in the world finding that SARS-CoV-2 RNA (the ribonucleic acid of the virus) is present in wastewater due to incorporation of bodily fluids of infected persons in such water, the team has built on this to check out run-off bathwater and also toilet effluence.
Before explaining how they performed their initial studies, Kandy National Hospital’s Consultant Clinical Microbiologist, Dr. Mahen Kothalawala reiterates that at this stage, the infection of COVID-19 is spreading rapidly and seems to have moved into the community, causing formidable challenges to the health authorities.
This is while large-scale screening of people for SARS-CoV-2 is “very costly” and there is also a short supply of test kits. Therefore, developing a cheap screening method is an immediate need to contain the spread of the disease, he says, stressing that there is growing evidence that SARS-CoV-2 and viral RNA are shed in body excreta, including saliva, sputum and faeces, and ultimately get disposed in wastewater.
Quoting studies, he says that as such the presence of SARS-CoV-2viral RNA in wastewater can be an “excellent” surveillance tool to identify the presence of disease in a community. Recent international reports indicate that this RNA was detected byRT-PCR in the faeces of patients.
“The sampling for such surveillance should be done continuously, looking for the RNA signature in wastewater. The RNA signature shows an upward trend 5 to 7 days before an outbreak and could act as an early warning. This could help zero-in on a particular locality rather than placing a blanket lockdown of a whole area. As such, it could pave the way to resume activities in the new normal,” he says. Dr. Kothalawala points out that some clinical studies have documented sustained RNA faecal shedding for up to seven weeks after the first onset of symptoms.
“Studies have also reported that in large proportions (18-31%), the epidemiology of viral infections can be monitored using this tool, even if clinical surveillance is not evident especially because traditional epidemiological approaches may be constrained by the asymptomatic nature of many SARS-CoV-2 viral infections and under-diagnosis of clinical cases,” he says, adding that wastewater monitoring also helps to detect low levels of the virus.
So it could be a handy tool even after public health interventions, when the number of infected cases decreases or individuals are asymptomatic, adds Dr. Kothalawala.
The pioneering team
The team includes the Director of the NIFS, Prof. Saman Seneweera who is a Molecular Biologist; the Kandy National Hospital’s Consultant Clinical Microbiologist, Dr. Mahen Kothalawala & Consultant Medical Virologist Dr. Rohitha Muthugala;the NIFS Material Scientist Dr. Lakmal Jayarathna, Material Chemist Prof. Asoka Kumara, Water Chemist Prof. Rohan Weerasooriya & Molecular Biologist Chandima Kamaral; the former Director of the Kandy Hospital, Dr. R.M.S.K.Rathnayake; the Provincial Director of Health Services,Dr. Nihal Weerasuriya; the Regional Director of Health Services, Dr. D.S.C. Thalagala; and Japan’s National Institute of Animal Health, Tsukuba, Toxicologist, Prof. KirthiGuruge.
| Effort to take forward initial studies through simple RT-PCR testing | |
| This multidisciplinary team hopes to take forward a preliminary study that they have carried out by conducting a project to develop a simple RT-PCR based method for SARS-CoV-2 surveillance in wastewater in Sri Lanka. “This rapid and low-cost wastewater-based disease surveillance can be carried out using specific primers. It will provide a window of opportunity to manage the disease at community level. The absence of an optimized and standardized protocol is one of the major challenges inthe detection/quantification of SARS-CoV-2 in wastewater samples,” says NIFS Director Prof. Saman Seneweera. The project through which nation-wide screening is being proposed is to be undertaken at the NIFS in collaboration with the Kandy National Hospital, with support from the Health Ministry. If the project becomes a reality, wastewater from densely-populated areas such as wattes, high-rise flats and even workplaces including factories and construction sites could be an indicator of disease prevalence, says Consultant Clinical Microbiologist Dr. Mahen Kothalawala. In a pilot study undertaken after obtaining needed approvals, this research team– clinical microbiologist, virologist, community medicine experts, molecular biologists, chemists and nanotechnologists – had studied wastewater samples from the Teldeniya and Kundasale Hospitals, both COVID-19 treatment centres in the Central Province, and detected “measurable” levels of the viral RNA. Explaining the methodology, Dr. Kothalawala says that concentration volumes of water are an important factor that can affect the results when detecting viruses.They collected samples from wastewater tanks at Teldeniya and Kundasale Hospitals – three replicates (500 mL each) from each location and processed them for SARS-CoV-2 detection, after filtration and concentration. Giving a basic overview, Consultant Medical Virologist Dr. Rohitha Muthugala said that processed water samples were stored at -70C until further analysis. RNA was extracted and purified.Finally, RT-PCR was carried out using specific primers for the detection of SARS-CoV-2 RNA. “The results arepromising and the method needs to be improved, after which it can be adopted for COVID-19rapid surveillance studies nationally,” he adds.
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