Quantitative microbial risk assessment to estimate health risks attributable to water supply: Can the technique be applied in developing countries with limited data?

Abstract

In the 3rd edition of its Guidelines for Drinking-Water Quality (2004) (GDWQ) the World Health Organization (WHO) promotes the use of risk assessment coupled with risk management for the control of water safety in drinking water supplies. Quantitative microbial risk assessment (QMRA) provides a tool for estimating the disease-burden from pathogenic microorganisms in water using information about the distribution and occurrence of the pathogen or an appropriate surrogate. This information may then be used to inform decisions about appropriate management of the water supply system. Although QMRA has been used to estimate disease burden from water supplies in developed countries, the method has not been evaluated in developing countries where relevant data may be scarce. In this paper, we describe a simplified risk assessment procedure to calculate the disease burden from three reference pathogens--pathogenic Escherichia coli, Cryptosporidium parvum and rotavirus--in water supplies in Kampala, Uganda. The study shows how QMRA can be used in countries with limited data, and that the outcome can provide valuable information for the management of water supplies.

Quantitative Microbial Risk Assessment to Estimate the Health Risk in Urban Drinking Water Systems of Mysore, Karnataka, India

“…Based on the assumption by several reports that 95 % of fecal coliforms were E. coli and 8 % of E. coli were pathogenic (Haas et al 1999;Howard et al 2006). In this study, the ratio used for E. coli: Pathogenic E. coli was 1: 08 (Haas et al 1999;Howard et al 2006); for E. coli: Campylobacter was 1: 066 (Smeets 2008;Machdar et al 2013); and for E. coli: Rotavirus it was 1: 10 −5 (Mara et al 2007;Machdar et al 2013). The dose-response parameter used in this study was Beta Poisson model as described by Haas et al (1999).…”

“…In this study, QMRA was performed as described by Haas et al (1999). The disease burden was calculated following the method described in the 4th Edition Table 1 Summery of water quality assessment used in this study of GDWQ (WHO 2011a, b) and Howard et al (2006). The procedure for estimation is summarized in Table 2.…”

“…The WHO advocates the use of health based water safety plans for provision of water that is safe to drink. In particular, WHO highlighted that the use of quantitative microbial risk assessment (QMRA) is a valuable tool for validation of water safety plans (Howard et al 2006;WHO 2011aWHO , b, 2004.…”

“…QMRA is a technique used to estimate the burden of diseases caused by individual causative agents rather than undifferentiated health effects (Haas et al 1999;Howard et al 2006). Exposure assessment, dose-response analysis, and risk characterization are the major tasks of QMRA as defined by Haas and Eisenberg (2001).…”

“…The E. coli results were also extrapolated for other pathogenic organisms such as Campylobacter and Rotavirus due to the lack of available pathogen concentration data and barriers in laboratory analysis. Hence many authors have been implemented initial QMRA work based on the indicator organisms (Howard et al 2006).…”