New sewage surveillance system to track Covid in Dhaka wastewater

The first-ever sewage surveillance system in the country to track Covid-19 by detecting SARS-CoV-2 RNA in sewage or wastewater is set to be introduced.

The surveillance system will work as an early indicator to allow 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, reads a press release.

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

Representatives of the Directorate General of Health Services (DGHS), Institute of Epidemiology Disease Control and Research (IEDCR), University of Virginia, USA; Imperial College London, UK and partners presented the new public health tool at an event in the capital on Tuesday.

The sewage surveillance system, which covers 33 different catchment areas in eight wards of the Dhaka North City Corporation, started its operation in June 2019, initially for poliovirus (Sabin vaccine strains), antimicrobial resistance genes, and other enteric pathogens.

After the coronavirus pandemic broke out in March 2020, the scope of the system was immediately expanded to test samples for the SARS-CoV-2 virus.

"Covid-19 diagnosis currently relies on sick people to seek medical help, but many 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 the sick can help address outbreaks of infectious disease, 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," said Mr Syed Mojibul Huq, additional secretary (Public Health Wing), Ministry of Health & Family Welfare.

Dr Mami Taniuchi, associate professor of ‎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. Hopefully, these insights will also help identify changes in transmission more accurately and help strengthen public health measures and surveillance for Covid-19."

Prof Meerjady Sabrina Flora, additional director general, DGHS said, "The Covid-19 pandemic is not ending anytime soon, we need to get ahead of it and thus must keep the rapid community transmission in check. It would be of great interest if we could have further analysis and scale up the surveillance system all over Dhaka city."

icddr,b Executive Director Dr Tahmeed said this type of surveillance system is an example of the type of research that can be efficiently used in the containment efforts of Covid-19.