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COVID-19 (2022 Deadline)
Designing and evaluating a wastewater pathogen monitoring tool for sewered and non-sewered sanitation systems to prevent disease outbreaks in Dakar, Senegal
PI: Nouhou Diaby (nouhou.diaby@ucad.edu.sn), Université Cheikh Anta Diop
U.S. Partner: William Tarpeh, Stanford University
Project Dates: November 2022 - March 2024
Project Overview
Wastewater-based epidemiology (WBE) is a rapid, cost-effective tool for tracking, mitigating, and preventing viral disease outbreaks. However, most WBE studies so far have focused on high-income, sewered locations, and WBE currently does not serve low-income countries that often rely at least partially on non-sewered sanitation.
This PEER project team aimed to expand WBE access and application by creating and piloting a novel WBE tool in Dakar, Senegal, through producing a comprehensive map of sanitation systems and sewage flows in Dakar and evaluating pathogen prevalence in wastewater throughout treatment and wastewater-impacted environments. To achieve these aims, Stanford University’s Tarpeh Lab, led by the U.S. partner, transferred knowledge and skills for mapping and geospatial modeling, supported methodological development for pathogen monitoring, and co-hosted workshops and stakeholder meetings to train Senegalese students and professionals.
Final Summary of Project Activities
With support from the National Sanitation Agency and the company Delvic Sanitation Initiatives, Dr. Diaby and his group were able to obtain updated maps of the sanitation network in Dakar, including maps of the sewer network and the rainwater network, with open drains, pumping stations, and wastewater treatment plants all indicated. The maps allowed them to estimate the populations connected to the network of sites included in the study. The researchers also gathered data on the sewer system’s nominal capacity and actual flow data through the sampling period. In the pumping stations monitored in this study, the flow rates were 19,200 m3/day at the University station, 10,800 m3/day at the Pikine station and 6,000 m3/day at the Almadies station. The Pikine and Almadies stations discharge their water into the Camberène water treatment plant, while the University station discharges directly into the sea without treatment.
From the study sites, the researchers gathered 50 samples of water to test for bacteria, parasites, and viruses. Nearly all samples (96.08%) revealed the presence of bacteria, while parasites were present in 84.31% of samples and viruses were present in 68.63%. The team used a subset of samples for SARS-CoV-2 detection. Out of 40 samples analyzed, the virus was detected in 26, equivalent to a rate of 65%. Detection of the virus revealed the presence of SARS-CoV-2 in the month of June 2023 in some locations (Pikine, Almadies, University, and Tivaouane Peulh), followed by a significant reduction, or even absence, during the winter period. On the other hand, SARS-CoV-2 reappeared in December 2023 in greater numbers.
As part of their work, the PEER team organized training courses covering sampling techniques, laboratory analysis and data processing. In total 49 people, 67% of them women, were able to benefit from training on wastewater-based epidemiology tools. The researchers also presented the project to the National High Council for Health Security “One Health” of Senegal, which is a key body bringing together all stakeholders in human, animal, and environmental health. They will continue this work with a $54,000 grant awarded from the Grand Challenge Canada. Thanks to the new equipment provided to Dr. Diaby’s lab with PEER funding, the group is well positioned to move forward with their research activities.
Back to PEER COVID-19 Grant Recipients
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