# High Detection Frequency of Enteric Pathogens: Insight from Wastewater-Based Epidemiology (WBE) Surveillance Approach in Dakar, Senegal

## TL;DR

This study shows that wastewater in Dakar, Senegal, contains many harmful pathogens, suggesting wastewater monitoring could help track diseases and prevent outbreaks.

## Contribution

The study demonstrates the feasibility of wastewater-based epidemiology in a region with limited sewer infrastructure, highlighting its potential for public health surveillance.

## Key findings

- Wastewater samples in Dakar showed high detection rates of bacterial, parasitic, and viral pathogens.
- Faecal sludge and pumping stations had higher pathogen counts than wastewater treatment plants and seawater.
- Seasonal variations and physicochemical parameters like BOD5 and turbidity influenced pathogen detection.

## Abstract

Public health relevance—How does this work relate to a public health issue?
Wastewater-Based Epidemiology (WBE) may serve as a complementary tool to clinical surveillance within the Senegalese context.WBE facilitates a more comprehensive understanding of pathogen circulation at the community level.

Wastewater-Based Epidemiology (WBE) may serve as a complementary tool to clinical surveillance within the Senegalese context.

WBE facilitates a more comprehensive understanding of pathogen circulation at the community level.

Public health significance—Why is this work of significance to public health?
The findings demonstrate the feasibility and significance of implementing wastewater-based epidemiology (WBE) in Senegal.Adoption of this approach would enable surveillance of enteropathogens and other emerging and re-emerging pathogens.

The findings demonstrate the feasibility and significance of implementing wastewater-based epidemiology (WBE) in Senegal.

Adoption of this approach would enable surveillance of enteropathogens and other emerging and re-emerging pathogens.

Public health implications—What are the key implications or messages for practitioners, policy makers and/or researchers in public health?
Wastewater samples contain a large number of pathogens of interest and may influenced by seasonal variations.Implementing a WBE program presents an opportunity to strengthen public health strategies, but requires careful consideration of organizational, logistical, and technological factors for effective execution.

Wastewater samples contain a large number of pathogens of interest and may influenced by seasonal variations.

Implementing a WBE program presents an opportunity to strengthen public health strategies, but requires careful consideration of organizational, logistical, and technological factors for effective execution.

Despite the importance of wastewater environmental monitoring in disease prevention and response strategies, its use remains poorly documented in Senegal. In addition, there is more onsite sanitation than sewer networks in Dakar, and open drains channel for rainwater are also used as clandestine wastewater discharge into the sea. This study aimed to assess the presence of specific pathogens in wastewater, faecal sludge, and bathing water (the sea). Samples were taken at treatment plants, an open drain, and in the receiving environment (the sea) from June to December 2023. Total nucleic acid was subjected to multiplex qualitative qPCR using SeeGene Allplex™ kits targeting 34 gastrointestinal pathogens. Descriptive statistics, multiple correspondence analysis (MCA) and logistic regression were performed. Considering all matrices, across 51 analysed samples, the results revealed strong bacterial (96.08%, n = 49), parasitic (84.31%, n = 43), and viral (68.63%, n = 35) presence. These results showed high levels of Aeromonas spp. (96.08%), Blastocystis hominis (80.39%), Enterocytozoon (58.82%), and Norovirus GII (74.51%) among bacteria, protozoa, helminths, and viruses, respectively. Moreover, faecal sludge and pumping station samples show more identified pathogen than wastewater treatment plant and seawater samples. The MCA revealed that the dry season is spatially associated with a greater number of pathogens than the rainy season, but the latter showed a greater species diversity. Logistic regression showed that certain physicochemical parameters, including BOD5, turbidity, pH, and suspended solids, influence pathogen detection. However, qualitative detection and sampling period may constitute limitations. These results reveal that wastewater and bathing water can serve as sources of information on the circulation of pathogens of interest with epidemic potential. Therefore, this valuable epidemiological tool could serve as an adjunct to clinical surveillance in order to prevent future epidemics.