A 30-day follow-up study on the prevalence of SARS-COV-2 genetic markers in wastewater from the residence of COVID-19 patient and comparison with clinical positivity

Wastewater Based Epidemiology (WBE) is an important tool to fight against COVID-19 as it provides insights into the health status of the targeted population from a small single house to a large municipality level in acost-effective, rapid and non-invasive way. The implementation of WBE-based surveillance could reduce the burden on the public health system, management of pandemics, help make informed decisions and protect public health. In this study, a house of COVID-19 patients was targeted for monitoring the prevalence of SARS-CoV-2 genetic markers in wastewater samples (WS) with clinical specimens (CS) over a period of 30 days. RT-qPCR technique was employed to target nonstructural (ORF1ab) and structural-nucleocapsid (N) protein genes of SARS-CoV-2, according to the validated experimental protocol. Physiological, environmental, and biological parameters were also measured following the American Public Health Association (APHA) standard protocol. SARS-CoV-2 viral shedding in wastewater peaked when the highest number of COVID-19 cases were clinically diagnosed. Throughout the study period, 7450 to 23,000 gene copies/1000 mL were detected, where we found 47 % (57/120) positive samples from WS and 35 % (128/360) from CS. When the COVID-19 patient number was the lowest (2), the highest CT value (39.4; i.e., lowest copy number) was identified from WS. On the other hand, when the COVID-19 patients were the highest (6), the lowest CT value (25.2 i.e., highest copy numbers) was obtained from WS. An increased signal of the SARS-CoV-2 viral load from the COVID-19 patient signal was found in the WS earlier than in CS. Using customized primer sets in a traditional PCR approach, we confirmed that all SARS-CoV-2 variants from CS and WS were Delta variants (B.1.617.2). To our knowledge, this is the first follow-up study to determine a relationship between COVID-19 patients and the discharge of SARS-CoV-2 RNA genetic markers in wastewater from a single house including all family members for clinical sampling from a developing country (Bangladesh) without a proper sewage system. The findings of the study indicate that monitoring the genetic markers of the SARS-CoV-2 virus in wastewater could identifyCOVID-19 cases, which reduces the burden on the public health system in COVID-19 pandemics.