A Longitudinal Study of Bacteriophages as Indicators of Norovirus Contamination of Mussels (Mytilus edulis) and Their Overlying Waters

Sewage pollution leads to the contamination of bivalve shellfish by pathogenic microorganisms. Bacterial indicators support the management of risks associated with the consumption of shellfish; however, they often fail to indicate adequately the potential hazard to human health posed by certain human enteric viruses. Bacteriophages have been proposed as alternative indicators that may more effectively predict the presence of enteric viral pathogens. This study explored the relationships between bacterial indicators (Escherichia coli (E. coli), faecal coliforms (FC) and intestinal enterococci (IE)), phages (somatic (SOMPH), F-specific RNA (F + PH) and human-specific Bacteroides GB-124 phages (GB124PH)) and Norovirus (NoV) (GI/GII) in mussels (Mytilus edulis) and their overlying waters. The bioaccumulation of these indicators and Norovirus in shellfish matrices (e.g., flesh, digestive gland) was investigated bimonthly over a 12-month period in an English estuary. The findings revealed a marked seasonality in the distribution of all organisms, with the highest levels occurring during the autumn/winter months. The levels of all phages in shellfish and their overlying waters correlated better with the levels of Norovirus than with those of bacterial indicators. Somatic coliphages were the indicator that exhibited the strongest correlations with NoV (rho = 0.929). This study suggests that relatively low-cost culture-based phage enumeration appears to offer a more accurate indication of the likely presence of Norovirus in mussels than traditional bacterial indicators

Modelling seasonal household variation in harvested rainwater availability:a case study in Siaya County, Kenya

Rainwater harvesting reliability, the proportion of days annually when rainwater demand is fully met, is challenging to estimate from cross-sectional household surveys that underpin international monitoring. This study investigated the use of a modelling approach that integrates household surveys with gridded precipitation data to evaluate rainwater harvesting reliability, using two local-scale household surveys in rural Siaya County, Kenya as an illustrative case study. We interviewed 234 households, administering a standard questionnaire that also identified the source of household stored drinking water. Logistic mixed effects models estimated stored rainwater availability from household and climatological variables, with random effects accounting for unobserved heterogeneity. Household rainwater availability was significantly associated with seasonality, storage capacity, and access to alternative improved water sources. Most households (95.1%) that consumed rainwater faced insufficient supply of rainwater available for potable needs throughout the year, with intermittencies during the short rains for most households with alternative improved sources. Although not significant, stored rainwater lasts longer for households whose only improved water source was rainwater (301.8 ± 40.2 days) compared to those having multiple improved sources (144.4 ± 63.7 days). Such modelling analysis could enable rainwater harvesting reliability estimation, and thereby national/international monitoring and targeted follow-up fieldwork to support rainwater harvesting

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

Containment, safe handling and disinfection of human excreta in cholera treatment centers (CTC) are key to preventing the onward spread of the disease. This study compared the efficacy of three chlorine-based approaches at concentrations of 0.5%, 1%, and 2% and one hydrated lime-based (Ca(OH)2 at 30% w:v) approach. Experiments followed existing Médecins Sans Frontières (MSF) cholera guidelines. Three simulated human excreta matrices consisting of either raw municipal wastewater (4.5 liters), or raw municipal wastewater plus 1%, or 20% faecal sludge (w:v), were treated in 14 liter Oxfam® buckets containing 125 mL of chlorine solution or hydrated lime suspension. Bacterial indicators (faecal coliforms (FC) and intestinal enterococci (IE)) and viral indicator (somatic coliphages (SOMPH)) were used to determine treatment efficacy following contact times of 10, 30 and 60min. Results showed that efficacy improved as chlorine concentrations increased. No statistical differences were observed with respect to the various contact times. Overall median log removal for 0.5% chlorine were: FC (1.66), IE (1.41); SOMPH (1.28); for 1% chlorine: FC (1.98), IE (1.82); SOMPH (1.79); and for 2% chlorine: FC (2.88), IE (2.60), SOMPH (2.38). Hydrated lime (30%) provided the greatest overall log removal for bacterial indicators (FC (3.93) and IE (3.50), but not for the viral indicator, SOMPH (1.67)). These findings suggest that the use of 30% hydrated lime suspensions or 2% chlorine solutions may offer a simple public health protection measure for the containment, safe handling, and disinfection of human excreta during humanitarian emergencies

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

<div><p>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 <i>Bacteroides fragilis</i> 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.</p></div

Box-plots displaying overall log reduction levels for viral indicators (C, D & E) following the addition of chlorine and hydrated lime to excreta matrices (pooled data n = 36; 2 contact times (Ct) x 2 mixing methods x 3 excreta matrices x 3 repetitions).

<p>* = Indicates a significant statistical difference in log reduction.</p

Flow chart of the human excreta containment experiments.

<p>Flow chart of the human excreta containment experiments.</p

Residual free chlorine (mg L^-1) following the addition of chlorine solutions to excreta matrices.

<p>Residual free chlorine (mg L^-1) following the addition of chlorine solutions to excreta matrices.</p