ABSTRACT
Wastewater-based epidemiology (WBE) monitoring can play a key role in managing future pandemics because it covers both pre-symptomatic and asymptomatic cases, especially in densely populated areas with limited community health care. In the present work, wastewater monitoring was employed in Ahmedabad, India, after the successful containment of the first wave of COVID-19 to predict resurgence of the disease in the expected second wave of the pandemic. Here we show wastewater levels of COVID-19 virus particles (i.e., SARS-CoV-2) positively correlated with the number of confirmed clinical cases during the first wave, and provided early detection of COVID-19 presence before the second wave in Ahmedabad and an WBE-based city zonation plan was developed for health protection. A eight-month data of Surveillance of Wastewater for Early Epidemic Prediction (SWEEP) was gathered, including weekly SARS-CoV-2 RNA wastewater analysis (n=287) from nine locations between September 2020 and April 2021. Across this period, 258 out of 287 samples were positive for least two out of three SARS-CoV-2 genes (N, ORF 1ab, and S). Monitoring showed a substantial decline in all three gene markers between October and September 2020, followed by an abrupt increase in November 2020. Similar changes were seen in March 2021, which preceded the second COVID-19 wave. Measured wastewater ORF-1ab gene copies ranged from 6.1 x 102 (October, 2020) to 1.4 x 104 (November, 2020) copies/mL, and wastewater gene levels typically lead confirmed cases by one to two weeks. The study highlights the value of WBE as a monitoring tool to predict waves within a pandemic, identifying local disease hotspots within a city and guiding rapid management interventions. HighlightsO_LIEight-months of SARS-CoV-2 gene variations explicitly predicts 2nd COVID-19 wave. C_LIO_LI258 out of 287 wastewater samples were positive for SARS-CoV-2 genes. C_LIO_LIWBE offers a lead time of 1-2 weeks relative to clinical cases. C_LIO_LIModel suggests that ORF 1ab gene is the most effective as a marker gene in WBE study. C_LIO_LIWBE RT-PCR screening for pathogens should be mandatory for global health monitoring. C_LI
ABSTRACT
Presence of SARS-coronavirus-2 (SARS-CoV-2) in wastewater sample has been documented in several countries. Wastewater-based epidemiology (WBE) is potentially effective for early warning of COVID-19 outbreak. The purpose of this study was to verify the detection limit of WBE for COVID-19. In total, 27 influent wastewater samples were collected from four wastewater treatment plants in Ishikawa and Toyama prefectures in Japan. During the study period, numbers of the confirmed COVID-19 cases in these prefectures increased from almost 0 to around 20 per 100,000 peoples. SARS-CoV-2 RNA in the samples were identified by several PCR-based assays. Among the 27 samples, 7 were positive for SARS-CoV-2 by at least one out of the three quantitative RT-PCR assays. These samples were also positive by RT-nested PCR assays. The detection frequency became higher when the number of total confirmed SARS-CoV-2 cases in 100,000 peoples became above 10 in each prefecture. However, SARS-CoV-2 could also be detected with a low frequency when the number was below 1.0. Considering that the number of the confirmed cases does not necessarily reflect the actual prevalence of the infection at the time point, data on the relationship between the number of infection cases and concentration in wastewater needs to be accumulated further.
