1. Relationships between extreme weather events and outbreaks of water-borne disease;

2. Associated changes in fecal bacterial concentrations in water and climate factors; and

3. Quantitative assessments of the relationship between various environmental factors (e.g., infrastructure and climate) and transmission risk for specific waterborne pathogens.

The essay concludes with a summary of critical needs that must be met in order to predict the effects of climate change on waterborne disease.

The subsequent contribution, by speaker Kelly Reynolds of the University of Arizona and Kristina Mena of the University of Texas-Houston, expands on a topic introduced by Rose: quantitative microbial risk assessment of waterborne disease. Reynolds and Mena observe that human pathogens make difficult subjects for risk assessment due to their “relatively low prevalence and infectious dose, specific virulence characteristics, and variably susceptible populations”; the vast diversity of water systems in use around the globe amplifies that challenge in the case of waterborne pathogens.

Following a description of microbial risk assessment methodologies for waterborne disease, the authors review representative studies (most of which were conducted in the United States) that describe drinking water contamination and the role of the water distribution system in spreading waterborne disease, as well as that played by premise plumbing and the biofilms present therein. They discuss the potential for improving risk assessment science by taking full advantage of the complementary relationship between epidemiological and forecasting studies, and also with increasingly accurate mathematical models and improved monitoring capacity.

That final, essential component of assessing risk for waterborne disease—pathogen monitoring—was the subject of a presentation in the same workshop session by Mark Sobsey of the University of North Carolina at Chapel Hill, entitled “Current Issues and Approaches to Microbial Testing of Water: Applicability and Use of Current Tests in the Developing World.” While clearly beneficial in industrialized countries, water testing is “essential” to providing safe water in developing countries, Sobsey observed. Water quality data informs the selection of promising sources for drinking water and appropriate treatments to ensure its safety, as well as the classification of existing sources for the purposes of studying their health effects. Unfortunately, he observed, most water tests are not accessible, are too complicated, or are too costly for use in developing countries.

Sobsey described the ideal microbial water test for low-resource settings as portable, self-contained, lab-free, electricity-free, low cost, globally available, able to support data communication, and capable of educating and mobilizing stakeholders, especially youth, to improve public health. These goals eventually may be met through a variety of approaches and options but are currently lim-