Advances in molecular biology are providing opportunities
Some of the most promising methods for direct pathogen
to develop innovative new microbial water quality monitor-
detection include the application of antibody based
ing techniques for the future. For example, applications of
methods.  Immunomagnetic separation technologies have
the polymerase chain reaction are increasingly being
been used successfully to concentrate and purify very
applied as tools to detect specific waterborne pathogens in
specific microorganisms.  Antibody methods can also be
aquatic ecosystems. Tremendous technological advances
used in combination with other methods such as with
also are occurring in fields such as genomics and
biosensors with liquid core wave guides that tend to
microfluidics. Genomics tools, such as DNA micro arrays,
enhance sensitivity.
7.6
offer the potential to immobilize hundreds to thousands of
DNA probes for different waterborne pathogens on a glass
Key microbes on the U.S EPA “Contaminant Candidate List”
microscope slide. The micro array can then be applied to
should and can be addressed.  For example:  Researchers
simultaneously screen a total DNA extract taken from
have recently raised questions about the human health
microorganisms in a water sample for many potential
significance of the bacterial pathogen Helicobacter pylori
pathogens. While there are challenges in applying such
in source waters used for drinking or recreation. While
molecular techniques to environmental samples, there is a
Helicobacter pylori is believed to be susceptible to existing
growing need to evaluate these new tools and seek ways to
methods of drinking water treatment, nonetheless, studies
enhance existing culture-based approaches for monitoring
in rural areas of Pennsylvania have found this pathogen in
microbial water quality.  It will be important to explore
well-waters that were determined to be coliform-free.
potential applications of these molecular tools for studying
Research is required to develop better methods to detect
the ecology of specific waterborne pathogens. For example,
potentially emerging pathogens like Helicobacter pylori in
the whole genomes of E. coli, Cryptosporidium, Giardia,
aquatic ecosystems, and to better understand their ecology
Helicobacter pylori and numerous viruses been se-
and the nature of the waterborne risk posed (Hegarty et al.
quenced, and genes can be immobilized onto a DNA micro
1999).  We still know little about the ecology of this
array with the potential to enable comprehensive diagnos-
pathogen, including its occurrence in aquatic ecosystems,
tic or detection systems that can tell much about water
and its potential for waterborne transmission.
quality and health risks.  In addition, this lends itself to
studies on gene expression, which may help to define key
Viruses in coastal waters have been found to be potential
survival and transport modes.
sources of risk to recreators and are detected in 20 to 80
percent of the impacted sites (Griffin et al. 2002).  Both cell
New methods are being used in the Great Lakes.  Investiga-
culture methods and molecular techniques were used to
tors have recently published a recent paper looking at the
address the pollution impact.  Much of the contamination
presence of a potentially “new” indicator system using PCR
was suspected to be associated with storm flows and septic
for rapid specific assessment in Lake Michigan (Brinkman
tanks.  This review focused on marine coastal waters as very
et al. 2003).  Results were available in four hours and
little work has been done in  fresh water lakes and coast-
correlations of 0.93 r values were found when comparing
lines.
the values to Enterococci, an indicator suggested by U.S.
EPA for marine waters.  More studies to address lower
Cryptosporidium remains a concern in the Great Lakes
detection limits, relationship to the E.coli standard and
water basin.  It is the tenth anniversary of the largest
public health risks should be supported.  In addition,
waterborne outbreak ever recorded in the U.S. that
geographic transportability of such new methods and
occurred in Milwaukee, Wisconsin and was associated with
relationships will need to be investigated associated with
contaminated water from Lake Michigan (MacKenzie et al.
nonpoint and point sources of pollution as well as storm
1995).  Associated with animal and human fecal wastes,
events.
new methods can now evaluate genotypes and infectivity
giving a clearer picture of the sources and public health
Ballast Waters
risks (Quintero-Betancourt et al. 2002).
Estimates suggest that 21 billion gallons of ballast water
Just as the Milwaukee outbreak had a tremendous impact
enter into U.S. waters per year (Greenman et al. 1997).
on the reauthorization of the U.S. Safe Drinking Water Act,
Ballast is defined as any solid or liquid that is brought on
the Walkerton outbreak of E.coli 0157H7 has promoted the
board a vessel to replace cargo, thereby stabilizing the
development of a Canadian drinking water quality policy
ship’s center of gravity.  In most cases, coastal water is
(Krewski et al. 2002).  The dramatic impact on the commu-
picked up as ballast in one area and carries with it a
nity associated with both illnesses and deaths caused by the
multitude of organisms that can then be disseminated
water supply has led to policies that will address basin/
globally and released as non-native and in many cases
aquifer protection and water quality monitoring and
harmful species.  Ballast waters originating from interna-
guidelines.
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