Dhaka’s sewage surveillance promises early detection of the virus that causes COVID-19 in the community, according to the icddr,b.
Moreover, the surveillance offers insights about hotspots to help strengthen virus containment measures and tracking of circulating strains and variants.
This new public health tool can successfully track COVID-19 through detecting SARS-CoV-2 RNA in sewage or wastewater, said icddr,b on Tuesday.
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 Covid-19 at a dissemination seminar in Dhaka.
The sewage surveillance system covers 33 different catchment areas in eight wards of the Dhaka North City Corporation (DNCC), 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 in the country, 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 pathogens 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.
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 a higher prevalence of COVID-19 and can allocate more of their limited testing resources to those areas and prevent further transmission.
“COVID-19 disease diagnosis currently relies on sick people to seek medical help, but many sick people do not seek help, many are also asymptomatic, thus authorities often remain unaware of the total number of infected individuals, leading to an underestimation of the community transmission of COVID-19.”
“Active surveillance systems like ours, which do not rely on the actions of sick people, can help address outbreaks of infectious diseases, such as COVID-19 more effectively” said Dr Rashidul Haque, Senior Scientist at iccdr,b.
“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. We also need to disseminate the results at the grassroots level so that we can change the behaviour of people.” said Mr Syed Mojibul Huq, Additional Secretary (Public Health Wing), Ministry of Health & Family Welfare of The Government of Bangladesh.
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.
icddr,b’s Executive Director, Dr Tahmeed Ahmed, in his address stressed 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 the equitable representation of COVID-19 in developing countries.
The sewage surveillance study was funded by the Bill and Melinda Gates Foundation.
nsrafsanju@gmail.com