The Coliform Index and Waterborne Disease Problems of Microbial Drinking Water Assessment

About this book

In the past decade there has been a rapid increase in waterborne outbreaks of disease associated with viral and protozoan agents, normally in drinking waters that were found to be microbially safe using the Coliform Index. For nearly a quarter of a century indicator organisms, in particular the coliform group, have been used to ensure the microbial quality of drinking water. Currently, world wide legislation to protect consumers is based on these outdated and unreliable tests and while there is considerable concern among scientists over their use, the water industry and regulators continue to place near total reliance on the Coliform Index. This book provides: * the first full account of the nature and applications of the Coliform Index * coverage of new and proposed water quality legislation: * details of emerging pathogens in water: * an evaluation of the role of the "coliform count" in future water quality analysis. It will be an essential tool for water companies at all levels, microbiologists, environmental health inspectors, environmental scientists and water engineers in industry whether working in developed countries or developing countries. Postgraduate students specialising in microbiology, civil and environmental engineering, environmental sciences and environmental health will find it a useful reference work as will undergraduates in these disciplines.

Contents

Preface. Microbial water quality: Introduction. The evolution of sanitary science. Waterborne outbreaks. Public health significance. Sources of waterborne disease. Risk assemssment. Legislation governing microbial water quality. Conclusions. Indicator organisms and the 'coliform concept': The origins of indicator organisms. The development of coliform as indicator organisms. Coliforms as indicators of water quality. The relevance of coliforms and faecal coliforms as faecal indicators in tropical conditions. The use of faecal coliforms as opposed to total coliforms. Conclusions. Evaluation of standard methods for the enumeration of coliforms from drinking waters: The multiple tube method (most probable number method). The membrane filtration method. Conclusions. Alternative techniques for the isolation and enumeration of coliforms and E. coli from drinking water: The presence-absence technique. Defined substrate technology (enzyme detection methods). Rapid methods. Immunodiagnostic techniques. The use of gene probes and PCR to detect coliforms in water. Conclusions. Alernative indicator systems for water quality analysis: Faecal streptococci. The faecal coliform/faecal streptococci (FC/FS) ratio. Clostridia perfringens. Bacteriophage. Bifidobacteria. Rhodococcus spp. Heterotrophic plate count bacteria. Other indicator organisms. Alternative indicators for tropical environments. Chemical indicators. Conclusions. The significance of emerging pathogens on water quality assessment: Giardia lamblia. Cryptosporidium spp. Viruses. Bacteria. Conclusions. The future of the coliform index: Introduction. The Coliform Index today. Future action. Final analysis. References. Index.

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