Evaluation of an Emergency Bulk Chlorination Project Targeting Drinking Water Vendors in Cholera-Affected Wards of Dar es Salaam and Morogoro, Tanzania

Abstract

. In August 2015, an outbreak of cholera was reported in Tanzania. In cholera-affected areas of urban Dar es Salaam and Morogoro, many households obtained drinking water from vendors, who sold water from tanks ranging in volume from 1,000 to 20,000 L. Water supplied by vendors was not adequately chlorinated. The Tanzanian Ministry of Health, Community Development, Gender, Elderly and Children and the U.N. Children’s Fund, Tanzania, collaborated to enroll and train vendors to treat their water with 8.68-g sodium dichloroisocyanurate tablets (Medentech, Ireland). The Centers for Disease Control and Prevention (CDC) provided monitoring and evaluation support. Vendors were provided a 3-month supply of chlorine tablets. A baseline assessment and routine monitoring were conducted by ward environmental health officers. Approximately 3 months after chlorine tablet distribution, an evaluation of the program was conducted. The evaluation included a full enumeration of all vendors, an in-depth survey with half of the vendors enumerated, and focus group discussions. In total, 797 (88.9%) vendors were included in the full enumeration and 392 in the in-depth survey. Free residual chlorine (FRC) was detected in 12.0% of tanks at baseline and 69.6% of tanks during the evaluation; however, only 17.4% of these tanks had FRC ≥ 0.5 mg/L. The results suggest high acceptability and use of the chlorine tablets by water vendors. However, given variation in the water source used and longer storage times, dosing could be increased in future programming. Bulk chlorination using chlorine tablets offers an efficient community-level approach to treating water closer to the point of use.

Cholera hotspots and surveillance constraints contributing to recurrent epidemics in Tanzania

“…According to existing literature, Dar es Salaam is one of the endemic cities experiencing cholera outbreaks in Tanzania [19]. This city was however not identified in our analysis as part of the hotspot areas.…”

A Critical Review of the Global Use and Context of Trucked Water as a Potable Water Supply

“…11,33,27 Unregulated groundwater wells were reportedly often used to supply the trucks with water for delivery; 34 however, surface water was sometimes used if water scarcity events were severe. 29,25 Trucked water delivery in these contexts was often viewed as "filling a service gap" during water scarcity events rather than an intended permanent solution for safe water provision. Less well-represented in the literature are scenarios where trucked water is used as a "regular" supply of drinking water for a population, defined as a community that is either in part or completely served by a trucked water distribution system throughout the year with supply patterns not driven by external events (e.g., droughts and natural disasters).…”

“…Poor water quality in a truck tanker was largely a result of poor source water quality 11,26,34 or inadequate treatment. 7,25,44 In locales where local or national guidelines for trucked water are available (e.g., Manitoba, Canada), the focus is primarily on delivered water quality, as opposed to source protection and quality. In our review, several different water sources to fill tanker trucks were identified: untreated surface waters, groundwater wells, water kiosks or water vending locations, and municipal piped water.…”

“…In our review, several different water sources to fill tanker trucks were identified: untreated surface waters, groundwater wells, water kiosks or water vending locations, and municipal piped water. 29,9,28,25,34 Variations in the source type and quality speak to the need to monitor and protect source waters and highlight the potential role of trucked water as an extension of existing water supply networks. The relatively high cost and poor water quality reported in several case studies are the most often cited reason trucked water supplies are not considered viable long-term solutions.…”

Risk Factors for Epidemic Cholera in Lusaka, Zambia—2017

“…Findings from this study highlight the need for more decentralized water treatment, at the household or community level, to reduce this risk. [24][25][26] Cholera risk has been estimated to be 36-100 times greater for people with neighborhood or household contacts with cholera cases. 27,28 Potential routes of infection include co-primary infection from consumption of a common contaminated food or water source, and secondary transmission via a food or water vehicle contaminated by an infectious housemate or neighbor.…”