Pathogen flows from on-site sanitation systems in low-income urban neighborhoods, Dhaka: A quantitative environmental assessment

Amin, Nuhu; Liu, Pengbo; Foster, Tim; Rahman, Mahbubur; Miah, Rana; Ahmed, Golam Bashir; Kabir, Mamun; Raj, Suraja; Moe, Christine L.; Willetts, Juliet

doi:10.1016/j.ijheh.2020.113619

Cited by 40 publications

(49 citation statements)

References 49 publications

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“…As urban populations grow, services should expand to meet their needs, but networked sanitation is not extending nearly rapidly enough to provide the necessary services (Öberg, Metson, Kuwayama, & A Conrad, 2020). On-site sanitation systems such as improved pit latrines and septic tanks become less appropriate as population density increases due to the safe management requirements of pit leachate, septage effluent and the safe removal of solids (Amin et al, 2020). The concept of Citywide Inclusive Sanitation (CWIS) seeks to overcome this technology dichotomy by focusing on service outcomes and promoting a range of solutions—both onsite and sewered, centralized or decentralized – to ensure everyone has equitable access to safely managed sanitation (Schrecongost, Pedi, Rosenboom, Shrestha, & Ban, 2020).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of User Experiences for the Clean Team Ghana Container-Based Sanitation Service in Kumasi, Ghana

Tidwell

Nyarko

Ross

et al. 2020

Preprint

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There is a lack of affordable and acceptable sanitation solutions for dense, low-income urban settlements. One option that has been proposed is container-based sanitation, where a sealed cartridge installed in a free-standing toilet is regularly changed and adequately separates users from their excreta. Though container-based toilets are considered a safely managed sanitation solution that meets the Sustainable Development Goal for sanitation, little is known about user experiences to inform how such a solution should be viewed by governments. We conducted a longitudinal prospective cohort study of changes in objective and subjective measures of sanitation quality due to the Clean Team Ghana (CTG) container-based toilet service in Kumasi, Ghana from June to December 2019. We collected data immediately prior to installation of a toilet and 10 weeks afterwards for 292 customers. Most initially used public toilets with good structural quality, but sometimes had poor cleanliness, a lack of handwashing facilities, and required a 14.3 minute mean round trip time to use. The evaluation found that CTG delivers a high-quality service that positively impacts the quality of life of CTG customers, as well as saving them money, reducing gender gaps in quality of life, and addressing the needs of those with physical disabilities. Satisfaction with CTG toilet and service characteristics was high, with the largest increases for satisfaction with smell, comfort, disgust, and privacy. Women in particular were positively impacted both for explicitly gendered indicators like the ability to practice menstrual hygiene management, and other indicators where women scored lower than men at baseline, including ease of access, ease of use, and cleanliness. Use of the service also benefitted those who had been unable to use a toilet for physical or social reasons beforehand. Problems with the CTG service, such as leaking, filling, smelling, or not being replaced as scheduled, were reported by fewer than 10% of customers. While one product or service does not fit the needs of all customers, this evaluation supports the growing body of evidence that container-based sanitation provides a service valued by users and acceptable to policymakers in dense urban settlements.

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Section: Introductionmentioning

confidence: 99%

Evaluation of User Experiences for the Clean Team Ghana Container-Based Sanitation Service in Kumasi, Ghana

Tidwell

Nyarko

Ross

et al. 2020

Preprint

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“…28 Although the UF method has been described previously, 17,27 our recent deployment of this technique to process field samples in Dhaka, Bangladesh demonstrated the feasibility and value of this method to detect a range of pathogens, including S. Typhi, in high proportions of drain, canal, and flood water samples in a low-resource setting. 18 "Moore swabs" have been used for decades by public health professionals around the world to detect and isolate enteric pathogens from wastewater and environmental waters, and their use to recover typhoidal Salmonella bacteria has recently been reviewed by Sikorski and Levine. 6 Consisting of a strip of cotton gauze tied with string and suspended in flowing water, this All rights reserved.…”

Section: Discussionmentioning

confidence: 99%

“…From April to October 2019, drain and canal water samples were collected in Mirpur, Dhaka, Bangladesh, a densely populated low-income area where residents live in compounds containing multiple families and the incidence of ST and SPA is high. 18,20 Large volume (20 L) samples were collected and concentrated by UF as described below. In Kolkata, India, Moore swabs were placed in three municipal sewage pumping stations between September 24, 2019 ST and SPA growth conditions.…”

Section: Study Sites and Environmental Sample Collectionmentioning

confidence: 99%

“…In contrast to the Moore swab method that only shows the presence or absence of a target pathogen, UF is a quantitative method that can simultaneously concentrate multiple pathogens from large volumes of water or wastewater, [15][16][17] and we recently reported the application of this method to detect S. Typhi in wastewater samples. 18 The Moore swab method offers several advantages over UF, specifically, Moore swabs are inexpensive, simple to use, and do not require collecting and transporting large volume samples of water or wastewater. However, UF can provide quantitative results with greater sensitivity which are valuable for microbial risk assessment or estimating infection prevalence.…”

Section: Introductionmentioning

confidence: 99%

“…However, UF can provide quantitative results with greater sensitivity which are valuable for microbial risk assessment or estimating infection prevalence. 18 The ability to detect and quantify ST/SPA in the environment is critical for monitoring and controlling transmission particularly in urban settings in low-and middle-income countries.…”

Section: Introductionmentioning

confidence: 99%

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Development of Moore Swab and Ultrafiltration Concentration and Detection Methods for Salmonella Typhi and Salmonella Paratyphi A in Wastewater and Application in Kolkata, India and Dhaka, Bangladesh

Liu

Ibaraki

Kapoor

et al. 2021

Preprint

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Enteric fever is a severe systemic infection caused by Salmonella enterica serovar Typhi (ST) and Salmonella enterica serovar Paratyphi A (SPA). Detection of ST and SPA in wastewater can be used as a surveillance strategy to determine burden of infection and identify priority areas for water, sanitation, and hygiene interventions and vaccination campaigns. However, sensitive and specific detection of ST and SPA in environmental samples has been challenging. In this study, we developed and validated two methods for concentrating and detecting ST/SPA from wastewater: the Moore swab trap method for qualitative results, and ultrafiltration (UF) for sensitive quantitative detection, coupled with qPCR. We then applied these methods for ST and SPA wastewater surveillance in Kolkata, India and Dhaka, Bangladesh, two enteric fever endemic areas. The qPCR assays had a limit of detection of 17 equivalent genome copies (EGC) for ST and 25 EGC for SPA with good reproducibility. In seeded trials, the Moore swab method had a limit of detection of approximately 0.05-0.005 cfu/mL for both ST and SPA. In 53 Moore swab samples collected from three Kolkata pumping stations between September 2019 to March 2020, ST was detected in 69.8% and SPA was detected in 20.8%. Analysis of sewage samples seeded with known amount of ST and SPA and concentrated via the UF method, followed by polyethylene glycol precipitation and qPCR detection demonstrated that UF can effectively recover approximately 8 log10 cfu, 5 log10 cfu, and 3 log10 cfu of seeded ST and SPA in 5 L, 10 L, and 20 L of wastewater. Using the UF method in Dhaka, ST was detected in 26.7% (8/30) of 20 L drain samples with a range of 0.11- 2.10 log10 EGC per 100 mL and 100% (4/4) of 20 L canal samples with a range of 1.02 - 2.02 log10 EGC per 100 mL. These results indicate that the Moore swab and UF methods provide sensitive presence/absence and quantitative detection of ST/SPA in wastewater samples, and these two methods can be used jointly or separately for Salmonella Typhi environmental surveillance.

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Identification of fecal contamination sources of groundwater in rural areas of Vhembe District Municipality, Limpopo Province, South Africa

Sekgobela,

Murei,

Khabo‐Mmekoa

et al. 2023

Water Environment Research

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Groundwater is a valuable source of drinking water worldwide, recognized as an improved drinking water source. However, on‐site sanitation systems may put groundwater at risk of fecal contamination. In the present study, two approaches were used to ascertain the sources of fecal contamination in groundwater used by communities of the Vhembe District Municipality. Overall, 87.5% of boreholes (n = 70) in the wet and 72.5% in the dry season were contaminated with Escherichia coli, and septic tank (n = 18) wastewaters displayed up to 104 cfu/mL E. coli. Host‐specific Bacteroidales quantitative polymerase chain reaction (qPCR) assays established the presence of human (BacHum and HF183) and animal (Cytb, BacCan, and Pig‐2Bac) genetic markers in groundwater from 15.7% of boreholes (wet) and 10% of boreholes (dry). No strong associations were founded between culturable E. coli counts and the presence/absence of marker genes for all the markers except for Cytb marker, which showed a weak significant correlation (r = 0.217; p = <0.01) between E. coli and the Cytb marker under dry seasonal conditions. Human markers and Cytb were present in the household septic tank wastewater samples. Significant differences in marker genes distribution in wastewater were observed using the Chi‐squared test: HF183 (p = <0.001) and BacHum (p = <0.001). Overall, no association was recorded between markers in groundwater and in wastewater for 18 households' septic tanks. A combined culturable E. coli and host‐specific Bacteroidales qPCR assays remain an appropriate approach for the identification of fecal contamination of groundwater.Practitioner Points Households primarily used private boreholes for drinking water, as a primary source. Most households used on‐site sanitation systems, including ventilated improved pit latrines and flush toilets connected to septic tanks. Escherichia coli was detected in groundwater, and the sources of fecal contamination were humans and animals (pigs, dogs, and chickens). The presence of human and animal markers in groundwater suggests that humans and animals are liable for fecal contamination. Fecal contamination in drinking water sources poses a significant concern due to pathogenic microorganisms posing potential human health risks.

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Pathogen flows from on-site sanitation systems in low-income urban neighborhoods, Dhaka: A quantitative environmental assessment

Cited by 40 publications

References 49 publications

Evaluation of User Experiences for the Clean Team Ghana Container-Based Sanitation Service in Kumasi, Ghana

Evaluation of User Experiences for the Clean Team Ghana Container-Based Sanitation Service in Kumasi, Ghana

Development of Moore Swab and Ultrafiltration Concentration and Detection Methods for Salmonella Typhi and Salmonella Paratyphi A in Wastewater and Application in Kolkata, India and Dhaka, Bangladesh

Identification of fecal contamination sources of groundwater in rural areas of Vhembe District Municipality, Limpopo Province, South Africa

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