Understanding COVID-19 Situation in Nepal and Implications for SARS-CoV-2 Transmission and Management

Quantification of multiple respiratory viruses in wastewater in the Kathmandu Valley, Nepal: Potential implications of wastewater-based epidemiology for community disease surveillance in developing countries

Despite being the major cause of death, clinical surveillance of respiratory viruses at the community level is very passive, especially in developing countries. This study focused on the surveillance of three respiratory viruses [severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IFV-A), and respiratory syncytial virus (RSV)] in the Kathmandu Valley, Nepal, by implication of wastewater-based epidemiology (WBE). Fifty-one untreated wastewater samples were from two wastewater treatment plants (WWTPs) between April and October 2022. Among eight combinations of the pre-evaluated methods, the combination of concentration by simple centrifugation, pretreatment by DNA/RNA Shield (Zymo Research), and extraction by the QIAamp Viral RNA Mini Kit (QIAGEN) showed the best performance for detecting respiratory viruses. Using this method with a one-step reverse transcription-quantitative polymerase chain reaction (RT-qPCR), SARS-CoV-2 RNA was successfully detected from both WWTPs (positive ratio, 100 % and 81 %) at concentrations of 5.6 ± 0.6 log10 copies/L from each WWTP. Forty-six SARS-CoV-2 RNA-positive samples were further tested for three mutation site-specific one-step RT-qPCR (L452R, T478K, and E484A/G339D), where G339D/E484A mutations were frequently detected in both WWTPs (96 %). IFV-A RNA was more frequently detected in WWTP A (84 %) compared to WWTP B (38 %). RSV RNA was also detected in both WWTPs (28 % and 8 %, respectively). This is the first study on detecting IFV-A and RSV in wastewater in Nepal, showing the applicability and importance of WBE for respiratory viruses in developing countries where clinical data are lacking.

SARS-CoV-2 Burden in Wastewater and its Elimination Using Disinfection

Background

Pathogenic viruses have been abundant and diverse in wastewater, reflecting the pattern of infection in humans. Human feces, urine, and perhaps other washouts that frequently circulate in sewage systems may contaminate wastewater with SARS-CoV-2. It's crucial to effectively disinfect wastewater since poorly handled wastewater could put the population at risk of infection.

Aims

To emphasize the presence and spread of SARS-CoV-2 in sewage (wastewater) through viral shedding from the patients to detect the virus in the population using wastewater-based epidemiology. Also, to effectively manage the transmission of SARS-CoV-2 and reduce the spread of the virus in the population using disinfectants is highlighted.

Methods

We evaluated articles from December 2019 to August 2022 that addressed SARS-CoV-2 shedding in wastewater and surveillance through wastewater-based epidemiology. We included the papers on wastewater disinfection for the elimination of SARS-CoV-2. Google Scholar, PubMed, and Research4Life are the three electronic databases from which all of the papers were retrieved.

Results

It is possible for viral shedding to get into the wastewater. The enumeration of viral RNA from it can be used to monitor virus circulation in the human community. SARS-CoV-2 can be removed from wastewater by using modern disinfection techniques such as sodium hypochlorite, liquid chlorine, chlorine dioxide, peracetic acid, and ultraviolet light.

Conclusion

SARS-CoV-2 burden estimates at the population level can be obtained via longitudinal examination of wastewater, and SARS-CoV-2 can be removed from the wastewater through disinfection.