Household Disinfection Interventions to Prevent Cholera Transmission: Facilitators, Barriers, Training, and Evidence Needs.

There are two common household disinfection interventions to prevent interhousehold transmission of cholera: household spraying, whereby a team disinfects cholera patients' households, and household disinfection kits (HDKs), whereby cleaning materials are provided to cholera patients' family members. Currently, both interventions lack evidence, and international agencies recommend HDK distribution; however, household spraying remains widely implemented. To understand this disconnect, we conducted 14 key informant interviews with international and national responders and a study in Haiti assessing HDK efficacy using two training modules including 20 household surveys and 327 surfaces samples before and after cleaning. During interviews, 80% of the international-level informants discussed evidence gaps for both interventions, and 60% preferred HDKs. Conversely, no national-level informants knew what an HDK was; therefore, they all preferred spraying. Informants discussed behavior changes, bleach perceptions, and implementation as facilitators and/or barriers to implementing both interventions. In households, training with demonstrations regarding the use of HDK led to increased reductions of Escherichia coli (P < 0.001) and Vibrio spp. (P < 0.001) on surfaces after participants cleaned the household compared with a hygiene promotion session only. These results emphasize the gap between the current international-level policy and the realities of cholera response programs, highlight the need for evidence to align household disinfection recommendations, and underscore the importance of the dissemination and training of responders and affected populations regarding methods to prevent intrahousehold cholera transmission.

Laboratory Efficacy of Locally Available Backwashing Methods at Removing Fouling in Hollow-Fiber Membrane Filters Used for Household Water Treatment.

Hollow-fiber membrane filters (HFMFs) for household water treatment (HWT) can efficaciously remove disease-causing organisms in laboratory settings. However, lower effectiveness in use in low- and middle-income countries (LMICs) and humanitarian contexts (HCs) has been observed and attributed to membrane fouling and the associated cleaning. In LMICs/HCs, it is not possible to prevent and control fouling using commonly known methods (e.g., testing influent water, maintenance regimes), and the literature on fouling/cleaning of HFMFs distributed in LMICs is scarce. As such, controlled laboratory experiments were conducted to determine the efficacy of locally available (in LMICs/HCs) backwashing solutions at removing fouling using different influent waters and HFMF types. Four commonly distributed HFMFs were selected; fouling layers were developed by filtering three influent water compositions, representing LMIC/HC waters, for 10-days, and bleach, water, or vinegar backwashing solutions were used for daily backwashing. Filter performance indicators included: fiber mechanical properties (strain at break, break force), water quantity performance (flow), water quality performance (turbidity, E. coli), and imaging. The study found fouling developed rapidly and altered mechanical properties and water quantity indicators within 200 h of filtration. Fouling did not decrease water quality indicators. Backwashing improved the filter's mechanical properties and water quantity performance, but it did not fully recover the initial performance. Additionally, recovery differed between backwashing solutions, and no universal cleaning recommendation appropriate for HFMFs in LMICs/HCs was identified. Overall, fouling development and control depended on HFMF type, influent water quality, and backwashing solution type; thus, caution before distributing HFMFs for long-term use in LMICs/HCs is recommended.

Modeling of Hydraulic Performance in Disks and Full-Scale Ceramic Water Filters.

Ceramic filters for household water treatment can improve water quality and reduce diarrheal disease. Hydraulic performance is critical for quality control and user acceptability, and hydraulic models have previously been developed and tested with experimental full-scale filters. As filters are cumbersome, there is interest in using disks instead of filters in laboratory efficacy studies. To assess the validity of disk use, we collected experimental volume from three sets of full-scale frustum-shaped filters and matching disks with different burn-out material sieve sizes and firing temperatures. We compared the experimental and fitted data by calibrating hydraulic conductivities from filters and disks. Hydraulic conductivities increased with larger burn-out material and higher firing temperatures but were comparable between filters and disks (2.00-6.15 × 10-7m·s-1 and 2.69-6.32 × 10-7m·s-1, respectively). We found that previously described hydraulic models successfully predicted cumulative volumes for filters and disks with rRMSE ranging from 2.1 to 9.6% (filters) and 3.4 to 4.7% (disks). The error increased slightly (rRMSE: 5.0-15%) when predicting hydraulic parameters for filters from the hydraulic conductivity of disks. Our results validate a method to predict full-scale filter hydraulic performance from hydraulic conductivity of disks and can be used to simplify and increase testing capacity, resulting in higher quality, more acceptable filters that improve household drinking water quality.