Field Trial of an Automated Batch Chlorinator System at Two Shared Shallow Tubewells among Camps for Forcibly Displaced Myanmar Nationals (FDMN) in Cox’s Bazar, Bangladesh

Chlorination of shallow tubewell water is challenging due to various iron concentrations. A mixed-method, small-scale before-and-after field trial assessed the accuracy and consistency of an automated chlorinator, Zimba, in Rohingya camp housing, Cox’s Bazar. From August–September 2018, two shallow tubewells (iron concentration = 6.5 mg/L and 1.5 mg/L) were selected and 20 households were randomly enrolled to participate in household surveys and water testing. The field-team tested pre-and post-treated tubewell and household stored water for iron, free and total chlorine, and E. coli. A sub-set of households (n = 10) also received safe storage containers (5 L jerry cans). Overall mean iron concentrations were 5.8 mg/L in Zimba water, 1.9 mg/L in household storage containers, and 2.8 mg/L in the project-provided safe storage containers. At baseline, 0% samples at source and 60% samples stored in household vessels were contaminated with E. coli (mean log10 = 0.62 MPN/100 mL). After treatment, all water samples collected from source and project-provided safe storage containers were free from E. coli, but 41% of post-treated water stored in the household was contaminated with E. coli. E. coli concentrations were significantly lower in the project-provided safe storage containers (log10 mean difference = 0.92 MPN, 95% CI = 0.59–1.14) compared with baseline and post-treated water stored in household vessels (difference = 0.57 MPN, 95% CI = 0.32–0.83). Zimba is a potential water treatment technology for groundwater extracted through tubewells with different iron concentrations in humanitarian settings.

Bacterial Composition of Biofilms of a Local Tigernut Drink Processing Unit in Yenagoa, Nigeria

Microorganisms grow and form biofilms on surfaces of equipment employed in food processing. These biofilms are considered as the major sources of contamination in the food industry. The study determined the bacterial load and composition on surfaces of equipment and utensils employed in tigernut drink production, from a vendor with a production unit located in an open market in Yenagoa, Nigeria. Swabs were taken from different sampling points made of varying materials—the grinding machine (metal), the collection bowls, water storage containers (thick plastic) and retail bottles (light plastic). These were analysed for total heterotrophic bacterial counts (THBC) and bacterial diversity using standard procedures. The THBC of water used in the drink production was also determined. The THBC of the sampling points ranged from log 3.28±0.06 cfu/cm2 to log 5.18±0.05 cfu/cm2, and log 5.13±0.07 cfu/ml for the water sample. The grinder and water recorded higher bacterial load with a statistically significant difference (P<0.05). The retail bottles had the least bacterial count. Shigella spp. were the most isolated (27.451%), then Salmonella spp. (21.568%) and E. coli (15.686%). Streptococcus spp., Staphylococcus spp. and Vibrio spp. were the least isolated (11.765% each). Shigella and Salmonella species occurred at all sampling points but not on the retail bottles. E. coli was present in the water collection bowls and retail bottles while Streptococcus, Staphylococcus and Vibrio were found only in the retail bottles. On diversity, four bacterial genera (39.216%) were isolated from the retail bottles, three (25.490%) from the water storage containers and two (17.647%) from the grinder and collection bowls. The microorganisms possibly had preference for attachment to the surfaces based on the material makeup and nutrient availability. Their occurrence and high numbers reflect the low level of hygiene employed prior to drink production. This could be of public health concern.

Modeling of the Sedimentation Process in Water

The sedimentation process occurs in water storage containers. In the sedimentation process, it will be observed how fluid flow occurs and how sedimentation occurs in water. The sedimentation is influenced by the density of the water and the velocity of the water in the water reservoir. This study aims to determine how to model a mixture of solid and liquid particles (suspension) in a water storage container by modeling it into a mathematical form, namely by using differential equations. In this case, the factors that affect the sludge concentration distribution will be used as a reference for modeling the Mathematical equations which will then be solved using differential equations.

Use of effective lids reduces presence of mosquito larvae in household water storage containers in urban and peri-urban Zika risk areas of Guatemala, Honduras, and El Salvador

Background In 2015, an outbreak of Zika virus spread across Latin America and the Caribbean (LAC). Public health programs promoted vector control behaviors, including covering water storage containers with lids. Such approaches disrupt Zika transmission by eliminating the habitats of the Aedes aegypti mosquito, which breeds in stagnant water. Methods A quantitative household survey and observation checklist with trained enumerators were undertaken between August and October 2018 in selected urban/peri-urban USAID implementation communities in El Salvador, Guatemala, and Honduras. The survey included questions regarding knowledge, attitudes, and practices related to Zika virus. An accompanying checklist was implemented to observe water storage containers, including for short-term and long-term water use. The characteristics of these containers were tabulated, including the presence of a lid. The lids were examined for key features to determine their potential effectiveness to prevent mosquito breeding: fully covering and sealing the container, not having holes, and not having water on them (potentially creating a secondary breeding site). Multivariate logistic regression was used to estimate the effectiveness of lid types and characteristics on the presence of larvae. Results Overall, in adjusted models, using an effective lid versus no lid was associated with a 94% decrease in odds of larval presence in long-term water storage containers (odds ratio = 0.06; 95% confidence interval [0.029, 0.152]); however, similar impacts were not observed for washbasins in the adjusted models. Models adjusted for household wealth, receiving a visit from a vector control technician, scrubbing the container in the last 7 days, and perception of more mosquitoes around. Conclusions Effective lids, if made available and coupled with complementary behavioral messaging, may reduce transmission of Zika and other Aedes mosquito-borne diseases in the LAC region.

Influence of Water Supply Conditions and Water Storage Containers on Aedes Mosquito Abundance in Makassar City, Indonesia

Background: High water demand accompanied with an unreliable piped water supply has forced urban residents to store water in containers. This situation potentially increases the number of breeding sites for mosquito vectors, such as Aedes. Method: This study aimed to test the hypothesis if piped water connection availability, tap water use, and highly stable tap water supply can help minimize the use of water storage containers as well as the presence of larvae and number of adult Aedes mosquitoes. We conducted a community-based entomological survey of 343 households from 36 neighborhoods or Rukun Tetangga in Makassar City, Indonesia. Our model based on the hypothesis was tested by piecewise structural equation modeling analysis. Results: A significant negative correlation was found between the stability of tap water supply and the number of water storage containers (−0.16, P < 0.05). Of the two categories of water storage containers, the unintentional water storage containers demonstrated a significantly (P < 0.001) higher effect on larval prevalence than the intentional one. Further, both container categories have significant indirect effects on the number of adult mosquitoes mediated by larval presence. Conclusion: Improving water supply condition, particularly by assuring a stable tap water supply, could minimize the use of intentional water storage containers. Furthermore, a regular community-wide health education program that targets the elimination of unintentional water storage containers, which can be breeding grounds for Aedes larvae mosquitoes, is necessary.