Assessment of recommended approaches for containment and safe handling of human excreta in emergency settings

Abstract

Ebola and cholera treatment centres (ETC and CTC) generate considerable quantities of excreta that can further the transmission of disease amongst patients and health workers. Therefore, approaches for the safe handling, containment and removal of excreta within such settings are needed to minimise the likelihood of onward disease transmission. This study compared the performance and suitability of three chlorine-based approaches (0.5% HTH, NaDCC and NaOCl (domestic bleach)) and three lime-based approaches (10%, 20% and 30% Ca(OH)2). The experiments followed recent recommendations for Ebola Treatment Centres. Three excreta matrices containing either raw municipal wastewater, or raw municipal wastewater plus 10% or 20% (w/v) added faecal sludge, were treated in 14 litre buckets at a ratio of 1:10 (chlorine solutions or lime suspensions: excreta matrix). The effects of mixing versus non-mixing and increasing contact time (10 and 30 mins) were also investigated. Bacterial (faecal coliforms (FC) and intestinal enterococci (IE)) and viral (somatic coliphages (SOMPH), F+specific phages (F+PH) and Bacteroides fragilis phages (GB-124PH)) indicators were used to determine the efficacy of each approach. Lime-based approaches provided greater treatment efficacy than chlorine-based approaches, with lime (30% w/v) demonstrating the greatest efficacy (log reductions values, FC = 4.75, IE = 4.16, SOMPH = 2.85, F+PH = 5.13 and GB124PH = 5.41). There was no statistical difference in efficacy between any of the chlorine-based approaches, and the highest log reduction values were: FC = 2.90, IE = 2.36, SOMPH = 3.01, F+PH = 2.36 and GB124PH = 0.74. No statistical difference was observed with respect to contact time for any of the approaches, and no statistical differences were observed with respect to mixing for the chlorine-based approaches. However, statistically significant increases in the efficacy of some lime-based approaches were observed following mixing. These findings provide evidence and practical advice to inform safe handling and containment of excreta and ensure more effective health protection in future emergency settings.

Assessment of Recommendation for the Containment and Disinfection of Human Excreta in Cholera Treatment Centers

“…Results of a previous research project undertaken at the University of Brighton (Applied Research on Disinfection to Prevent Ebola Transmission and funded by USAID) assessed the efficacy of various 0.5% (5000 mg/L) chlorine solutions (HTH, NaDCC, and household bleach) and hydrated lime suspensions (10%, 20%, and 30% (w:v)) at removing viruses and bacteria within excreta matrices. These recently published results [34] demonstrated that lime suspensions, particularly at 30% w/v, were considerably more effective than 0.5% chlorine solutions, especially when excreta matrices contained high concentrations of solids and organic matter. However, a chlorine solution of only 0.5% [9][10][11] was used for this previous study, which is considerably lower than the MSF cholera guideline [12], which recommends the use of 2% (20,000 mg/L) chlorine solutions for the containment and disinfection of human excreta in CTCs.…”

“…It is interesting to note that the 30% lime solution did not lose its efficacy even as the load of organic matter and suspended solids increased in the excreta matrices from 0% to 10% and 20%. As mentioned previously, this study evolved from (and built upon findings of) earlier research [34]. However, the study differed (as outlined in the materials and methods section) in that it focused on trying to understand the performance of higher chlorine concentrations (1% and 2%), and different volumes (125 mL) of the chlorine solutions and lime suspension to treat and contain human excreta.…”

“…Only NADCC chlorine compound was used to produce chlorine solutions, the reason was that in the previous study [34], there was no statistical difference in treatment efficacy when compared to the other compounds (HTH and bleach (NaOCl)).…”

“…In this study, hydrated lime was only tested at the 30% concentration (not at 10% or 20%), this was because previous research [34] showed that it presented the highest efficacy to contain and treat excreta matrices.…”

“…Only somatic coliphages (not F-specific coliphages and/or phages of Bacteroides fragilis GB-124) were used as viral indicators when testing treatment efficacy, this was because somatic coliphages were the most resistant [34].…”