Dhaka’s sewage surveillance for SARS-CoV-2 offers an insight into community transmission and forecasting

Dhaka’s sewage surveillance for SARS-CoV-2 offers an insight into community transmission and forecasting, promising early detection of the virus to help strengthen its containment measures, and tracking of circulating strains and variants.

The finding was revealed at a dissemination seminar held at Six Seasons Hotel in the city.

icddr,b, University of Virginia, USA; Imperial College London, UK; Institute of Epidemiology Disease Control and Research (IEDCR), Bangladesh; the Directorate General of Health Services (DGHS), Bangladesh and partners have presented the first-ever sewage surveillance system for SARS-CoV-2 in Dhaka.

The sewage surveillance study was funded by the Bill and Melinda Gates Foundation.

This new public health tool can successfully track COVID-19 through detecting SARS-CoV-2 RNA in sewage or wastewater.

The sewage surveillance system covers 33 different catchment areas in eight wards of the Dhaka North City Corporation (DNCC) and started in June 2019, initially for poliovirus (Sabin vaccine strains), antimicrobial resistance genes, and other enteric pathogens. When the COVID-19 pandemic broke out in March 2020, the scope of the system was immediately expanded to test samples for SARS-CoV-2 virus.

Since then, weekly sewage samples are collected from each catchment area and the amount of viral pathogen in the system is quantified using a method called reverse transcription quantitative PCR (qRT-PCR).

The viral load associated with each sample collection site is then connected to its watershed through sewage and drainage line tracing and provides a measure of how many infected people there are in the area.

Finally, all these data and analysis are presented through an online dashboard hosted at the following link -- https://dhakacovidtracker.research.virginia.edu/.

The surveillance system works as an early indicator, which allows public health officials to predict an increasing or decreasing trend of infection around a week prior to the rise or fall in COVID-19 cases.

With this knowledge, public health officials can visualise which regions have higher prevalence of COVID-19 and can allocate more of their limited testing resources to those areas and prevent further transmission.

They can also implement public health interventions specific to a particular location and keep the citizens of the community as safe as possible.

“This type of research being done on the sewerage system is very new to Bangladesh. We may be able to disseminate the findings internationally and show the world how we can do surveillance through sewage systems,” said Mr Syed MojibulHuq, additional secretary (Public Health Wing), Ministry of Health & Family Welfare.

“We also need to disseminate the results at the grassroots level so that we can change the behaviour of people,” said Mr Huq.

“In developing countries like Bangladesh this type of research is necessary. As the Covid-19 pandemic has led to the loss of thousands of lives, we need to find ways that can assist us in surveillance and containment,” said Brigadier General Md Zobaydur Rahman, chief health officer, Dhaka North City Corporation.

Speaking on the prospects of detecting emerging strains and variants, Dr Mami Taniuchi, associate professor from the University of Virginia, said, “We are establishing a robust system to track circulating strains and variants of SARS-CoV-2. We initiated the work and are presently analysing the data.

Commenting on the prospects of the sewage surveillance in Dhaka, Prof Meerjady Sabrina Flora, additional director general of DGHS, said, “The COVID-19 pandemic is not ending anytime soon, we need to get ahead of it and thus we must keep the rapid community transmission in check.”

icddr,b’s Executive Director, Dr Tahmeed Ahmed, in his address stressed on the importance of using this surveillance system efficiently .

The dashboard and sewage surveillance pilot study in Dhaka will hopefully prove that specific and distinct representation of SARS-CoV-2 is possible in heavily populated countries and will justify efforts to increase equitable representation of COVID-19 in developing countries.

The sewage surveillance study was funded by the Bill and Melinda Gates Foundation.

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