Environmental Survey of Drinking Water Sources in Kampala, Uganda, during a Typhoid Fever Outbreak

Abstract

In 2015, a typhoid fever outbreak began in downtown Kampala, Uganda, and spread into adjacent districts. In response, an environmental survey of drinking water source types was conducted in areas of the city with high case numbers. A total of 122 samples was collected from 12 source types and tested for , free chlorine, and conductivity. An additional 37 grab samples from seven source types and 16 paired large volume (20 liter) samples from wells and springs were also collected and tested for the presence of serovar Typhi. was detected in 60% of kaveras (drinking water sold in plastic bags) and 80% of refilled water bottles; free chlorine was not detected in either source type. Most jerry cans (68%) contained and had free chlorine residuals below the WHO-recommended level of 0.5 mg/liter during outbreaks. Elevated conductivity readings for kaveras, refilled water bottles, and jerry cans (compared to treated surface water supplied by the water utility) suggested that they likely contained untreated groundwater. All unprotected springs and wells and more than 60% of protected springs contained Water samples collected from the water utility were found to have acceptable free chlorine levels and no detectable While Typhi was not detected in water samples, spp. were detected in samples from two unprotected springs, one protected spring, and one refilled water bottle. These data provided clear evidence that unregulated vended water and groundwater represented a risk for typhoid transmission. Despite the high incidence of typhoid fever globally, relatively few outbreak investigations incorporate drinking water testing. During waterborne disease outbreaks, measurement of physical-chemical parameters, such as free chlorine residual and electrical conductivity, and of microbiological parameters, such as the presence of or the implicated etiologic agent, in drinking water samples can identify contaminated sources. This investigation indicated that unregulated vended water and groundwater sources were contaminated and were therefore a risk to consumers during the 2015 typhoid fever outbreak in Kampala. Identification of contaminated drinking water sources and sources that do not contain adequate disinfectant levels can lead to rapid targeted interventions.

Review of Methods Suitable for Environmental Surveillance of Salmonella Typhi and Paratyphi

“…The sample volume collected varies from several milliliters to several liters. Water is then transferred to sterile plastic (Nalgene) containers [ 23 , 25 ], sterile glass bottles [ 7 , 17 , 26–28 ], sterile Abba-type (stainless steel) bottles [ 24 ], glass sample cells [ 29 ], or sterile WhirlPak bags [ 29 , 30 ] and transported to a laboratory. Samples are typically stored in a cooler on ice or kept at 4°C during transport and until processing (usually within 48 hours) [ 3 , 23–27 , 29–34 ].…”

“…Water is then transferred to sterile plastic (Nalgene) containers [ 23 , 25 ], sterile glass bottles [ 7 , 17 , 26–28 ], sterile Abba-type (stainless steel) bottles [ 24 ], glass sample cells [ 29 ], or sterile WhirlPak bags [ 29 , 30 ] and transported to a laboratory. Samples are typically stored in a cooler on ice or kept at 4°C during transport and until processing (usually within 48 hours) [ 3 , 23–27 , 29–34 ]. Physicochemical characteristics of the water sampled are also generally collected, including temperature, pH, conductivity, salinity, and dissolved oxygen [ 9 , 17 , 23–26 , 29 , 30 , 32 , 35–37 ].…”

“…Samples are typically stored in a cooler on ice or kept at 4°C during transport and until processing (usually within 48 hours) [ 3 , 23–27 , 29–34 ]. Physicochemical characteristics of the water sampled are also generally collected, including temperature, pH, conductivity, salinity, and dissolved oxygen [ 9 , 17 , 23–26 , 29 , 30 , 32 , 35–37 ]. Some environmental studies collect large volumes of water (several liters) and sample concentration is performed prior to analysis.…”

Wilderness Medical Society Clinical Practice Guidelines for Water Disinfection for Wilderness, International Travel, and Austere Situations

“…Furthermore, in underdeveloped countries, the quality of bottled water may not meet the standards of developed countries and may contain pathogenic microbes. 25 The term disinfection, the desired result of field water treatment, is used here to indicate the removal or destruction of harmful microorganisms, which reduces the risk of illness. This is sometimes used interchangeably with purification, but the latter term more accurately indicates the removal of organic or inorganic chemicals and particulate matter to improve color, taste, and odor.…”

A bioassay-based protocol for chemical neutralization of human faecal wastes treated by physico-chemical disinfection processes: A case study on benzalkonium chloride

“…In the US and many other high-income countries with presumably adequate treatment facilities, human faecal waste and other potentially infectious bodily fluids from healthcare facilities can be discharged directly into local sewage systems. In situ pre-treatment of such human waste is sometimes encouraged under certain conditions such the introduction of high risk diseases and their pathogens into the population, such as cholera (Ashbolt, 2004) (Centers for Disease and Prevention, 2010), typhoid fever (Murphy et al, 2017), Ebola (CDC, 2014a; and infectious hepatitis (Craun et al, 2010) (Sehulster et al, 2003) (Spina et al, 2017). The World Health Organization (WHO), has https://doi.org/10.1016/j.ijheh.2018.07.002 Received 7 February 2018; Received in revised form 28 June 2018; Accepted 3 July 2018 recommendations for management of such wastes using a disinfection option (Prüss et al, 1999;WHO, 2014;WHO and Unicef, 2014).…”