4 days ago
How to detect early signs of disease outbreak? Govt's plan is to expand wastewater surveillance
The system works as an early detection system for outbreaks, allowing public health officials to better understand and respond to public health threats. People infected with certain viruses and bacteria shed the pathogens in their feces or urine even if they are asymptomatic or do not seek medical care.
The initiative led by the Indian Council of Medical Research (ICMR) in collaboration with some other government and private agencies, including the National Centre for Disease Control (NCDC), is set to be rolled out over the next six months. Now identified and deployed as an important public health tool worldwide, it allows authorities to detect disease-causing germs in wastewater by testing for their nucleic makeup in the sewage.
New Delhi: The central government has decided to massively expand wastewater surveillance across the country, setting a target for itself to identify more than 10 disease-causing germs. Besides picking early warning signs of outbreaks, the move is also aimed at quicker implementation of strategies to manage infectious diseases.
Public health laboratories can then test untreated samples from municipal wastewater facilities and detect the presence and burden of these germs in the population.
The pathogens that will be surveilled through the project will include non-typhoidal salmonella, Taenia solium, Entamoeba histolytica, Giardia lamblia, Ascaris, Listeria monocytogenes and Leptospira—that cause serious stomach, liver or diarrheal infections—as well as the highly infectious Mycobacterium tuberculosis and NewCastle disease virus.
In addition, said ICMR director general Dr Rajiv Bahl, pathogens causing deadly avian or bird flu will also be surveyed through the project.
'We will test the pathogens that can test … whatever is likely to come in wastewater, we are going to test,' Dr Bahl told ThePrint, adding that most infectious disease outbreaks manifest symptoms like fever, diarrhea and respiratory illnesses.
In India, wastewater surveillance was first started in 2001 with the help of the World Health Organization (WHO) to track poliomyelitis or polio-causing viruses as part of the National Public Health Surveillance (NPHS) programme. In 2020, during the COVID-19 pandemic, the programme was expanded to include SARS-CoV-2 strains.
The latest expansion of the project, to be conducted through animal-human interface projects in 3 slaughterhouses and 11 bird sanctuaries in different cities, will also include all coronaviruses, ICMR scientists said.
The move is particularly significant given the constant threat of massive disease outbreaks of zoonotic origin or viruses that jump from animals and birds to humans, mainly propelled by climate change.
Currently, polio virus is routinely tested across the country at 65 sites under the NPHS.
Additionally, as an extension of the programme, it is also being deployed to identify antimicrobial resistance (or AMR)—which poses a major threat to public health due to resistance in disease-causing agents against available antibiotics—across 60 hospitals in the country.
Also Read: Gut health probiotics now among top selling drugs in India, but doctors advise caution against hype
Granular data without individual testing
Wastewater surveillance integrates expertise from fields such as public health, ecology, urban planning, and virology, recognising the interconnectedness of human, animal, and environmental health, serving as a key component of the 'One Health' concept.
Experts ThePrint spoke to said the standard procedure is wastewater sample collection, nucleic acid extraction and amplification, followed by its testing to quantify pathogens with PCR-based methods (aimed at looking for specific pathogens) or next-generation sequencing (NGS), which is used for variant detection.
Given the nature of wastewater which comprises waste from households, livestock and environment and many other components that end up in it, the information generated is significant, and at minimal cost.
Dr Rakesh Kumar Mishra, scientist and director of Bengaluru-based Tata Institute of Genetics and Society, who specialises in genomics and epigenetics, told ThePrint that just a few samples, from cities with millions of people, for example, can indicate the circulating pathogens without testing individuals.
For instance, in cities with good sewage systems, it is possible to detect pathogens specific to a locality.
The surveillance is more effective in generating crucial and granular pathogen-related information from cities with better planned sewage systems but can also give a rough idea from others, said Dr Mishra.
Dr Mishra is also the chief principal investigator of the Alliance for Pathogen Surveillance Innovations (APSI), which is a multi-city consortium of research, clinical, public and private institutions.
APSI has been working with the ICMR and NCDC on the wastewater surveillance project.
Scientific studies have established that detecting viruses in wastewater gives decision-makers a lead time of 10-14 days. This time can be vital for public health authorities to re-look at priorities, reallocate human resources, vaccinate targeted groups and alert the medical fraternity.
This is what happened in Canada in 2023 during an outbreak of Respiratory Syncytial Virus or RSV—a pathogen that can lead to high numbers of hospitalisation.
(Edited by Amrtansh Arora)
Also Read: ICMR confirms diarrhoeal pathogen in Guillain-Barre Syndrome case samples but cause of outbreak unclear
