Waterborne Disease Outbreaks and the Multi-barrier Approach to Protecting Drinking Water - Global Drinking Water Management and Conservation - page 11

Chapter 2
Waterborne Disease Outbreaks
and the Multi-barrier Approach
to Protecting Drinking Water

2.1 Introduction

Drinking water outbreaks have occurred throughout the world, causing varying
illnesses and even death. This chapter reviews past outbreaks of microbial con-
taminants and the associated lessons that have been learnt. Only the most recent
outbreaks are considered, as these are probably the most relevant for policy pur-
poses. The publication, Safe Drinking Water: lessons from recent outbreaks in
af uent nations, written by Hrudey and Hrudey ( 2004 ), summarize the occurrences

of 69 drinking water outbreaks. They begin in January 1974 in Richmond Heights
(Florida), and continue up to March 2002 in Transtrand (Sweden). The Hrudeys
have made a signi

cant contribution to the topic of drinking water safety through
the detailed account of these outbreaks, and their overall analyses. Their topic
emphasizes the impact of the Walkerton contamination of 2000, and also describes
the lessons that have been gained as a result. While taking the Hrudeys work into

consideration, the objective of this chapter is to include outbreaks that have
occurred since 2002, and to expand upon their conclusions.
A variety of contaminants have caused water outbreaks, but a few in particular
are a primary concern. Cryptosporidium parvum, Giardia lamblia, Campylobacter
jejuni, and Escherichia coli (E. coli) have caused the largest and most signi

'

cant
outbreaks, and therefore are the main focus. Toxoplasma gondii is also included,
but this pathogen is very rare and does not pose the same level of risk. These
disease-causing contaminants are most commonly transmitted into water sources by
animal or human fecal matter. The three categories of microbial contaminants in
drinking water are protozoa, bacteria, and viruses. Protozoa and bacteria contam-
inants have had the most signi

cant impacts and are the focus of this review.
Outbreaks can occur because of an array of factors. The multi-barrier approach is
the primary strategy for enhancing safety of drinking water systems. This approach
is designed to provide the best quality of water by using a number of checkpoints
throughout a water system. If a contaminant enters the water system, it is the goal of