AUTHOR
Murphy JL, Kahler AM, Nansubuga I, Nanyunja EM, Kaplan B, Jothikumar N, Routh J, Gómez GA, Mintz ED, Hill VR
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 were collected from 12 source types and tested for E. coli, free chlorine, and conductivity. An additional 37 grab samples from seven source types and 16 paired large volume (20-L) samples from wells and springs were also collected and tested for the presence of Salmonella Typhi. Escherichia coli 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 E. coli and had free chlorine residuals below the WHO recommended level of 0.5 mg/L during outbreaks. Elevated conductivity readings for kaveras, refilled water bottles, and jerry cans (compared to treated surface water supplied by the water utility) suggested they likely contained untreated ground water. All unprotected springs and wells and more than 60% of protected springs contained E. coli Water samples collected from the water utility were found to have acceptable free chlorine levels and no detectable E. coli While S Typhi was not detected in water samples, Salmonella 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 ground water represented a risk for typhoid transmission.Importance 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 microbiological parameters, such as the presence of E. coli or the implicated etiologic agent, in drinking water samples can identify contaminated sources. This investigation indicated that unregulated vended water and ground water 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.
Click here to view the article, published in Applied and environmental microbiology
