Longitudinal wastewater-based surveillance of SARS-CoV-2 during 2023 in Ethiopia

• Published in: Frontiers in public health Vol. 12; p. 1394798
• Main Authors: Abera Dinssa, Daniel, Gebremicael, Gebremedhin, Mengistu, Yohannes, Hull, Noah C, Chalchisa, Dinknesh, Berhanu, Girma, Gebreegziabxier, Atsbeha, Norberg, Ashley, Snyder, Sarah, Wright, Sarah, Gobena, Waktole, Abera, Adugna, Belay, Yohannes, Chala, Dawit, Gizaw, Melaku, Getachew, Mesay, Tesfaye, Kirubel, Tefera, Mesfin, Belachew, Mahlet, Mulu, Tegegne, Ali, Solomon, Kebede, Abebaw, Melese, Daniel, Abdella, Saro, Rinke de Wit, Tobias F, Kebede, Yenew, Hailu, Mesay, Wolday, Dawit, Tessema, Masresha, Tollera, Getachew
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 07.10.2024
• Subjects: COVID-19; COVID-19 - epidemiology; Ethiopia - epidemiology; Humans; Longitudinal Studies; Public Health; qRT-qPCR; RNA, Viral - analysis; RNA, Viral - isolation & purification; SARS-CoV-2; SARS-CoV-2 - isolation & purification; Wastewater - microbiology; Wastewater - virology; wastewater treatment plants; Wastewater-Based Epidemiological Monitoring; wastewater-based epidemiology; Ethiopia; COVID-19; qRT-qPCR; SARS-CoV-2; wastewater treatment plants; wastewater-based epidemiology
• ISSN: 2296-2565; 2296-2565
• DOI: 10.3389/fpubh.2024.1394798

Although wastewater-based epidemiology (WBE) successfully functioned as a tool for monitoring the coronavirus disease 2019 (COVID-19) pandemic globally, relatively little is known about its utility in low-income countries. This study aimed to quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater, estimate the number of infected individuals in the catchment areas, and correlate the results with the clinically reported COVID-19 cases in Addis Ababa, Ethiopia. A total of 323 influent and 33 effluent wastewater samples were collected from three Wastewater Treatment Plants (WWTPs) using a 24-h composite Moore swab sampling method from February to November 2023. The virus was captured using Ceres Nanotrap® Enhancement Reagent 2 and Nanotrap® Microbiome A Particles, and then nucleic acids were extracted using the Qiagen QIAamp Viral RNA Mini Kit. The ThermoFisher TaqPath™ COVID-19 kit was applied to perform real-time reverse transcriptase polymerase chain reaction (qRT-PCR) to quantify the SARS-CoV-2 RNA. Wastewater viral concentrations were normalized using flow rate and number of people served. In the sampling period, spearman correlation was used to compare the SARS-CoV-2 target gene concentration to the reported COVID-19 cases. The numbers of infected individuals under each treatment plant were calculated considering the target genes' concentration, the flow rate of treatment plants, a gram of feces per person-day, and RNA copies per gram of feces. SARS-CoV-2 was detected in 94% of untreated wastewater samples. All effluent wastewater samples (  = 22) from the upflow anaerobic sludge blanket (UASB) reactor and membrane bioreactor (MBR) technology were SARS-COV-2 RNA negative. In contrast, two out of 11 effluents from Waste Stabilization Pond were found positive. Positive correlations were observed between the weekly average SARS-CoV-2 concentration and the cumulative weekly reported COVID-19 cases in Addis Ababa. The estimated number of infected people in the Kality Treatment catchment area was 330 times the number of COVID-19 cases reported during the study period in Addis Ababa. This study revealed that SARS-CoV-2 was circulating in the community and confirmed previous reports of more asymptomatic COVID-19 cases in Ethiopia. Additionally, this study provides further evidence of the importance of wastewater-based surveillance in general to monitor infectious diseases in low-income settings. Wastewater-based surveillance of SARS-CoV-2 can be a useful method for tracking the increment of COVID-19 cases before it spreads widely throughout the community.