 University of Wisconsin-Madison research
team will be mixing up a batch of "pathogen cocktails" in the
laboratory, with the goal of countering disease-causing threats to drinking
water.
 Civil Engineering Professor Greg
Harrington is leading a two-year project to determine how well water-treatment
technologies remove cryptosporidium and other microorganisms before they
reach the kitchen tap.
The $250,000 project is funded by
the U.S. Environmental Protection Agency and the American Water Works Association
Research Foundation, an international nonprofit group devoted to drinking-water
quality. Joining Harrington in the project will be Jon Standridge and David
Battigelli, scientists at the Wisconsin State Laboratory of Hygiene.
"If we review waterborne outbreaks
of infectious disease in the United States, we find that the culprit was
identified in only about half the cases," says Harrington. "There
are numerous microorganisms, but detection methods are available for only
a small fraction."
This project will focus on a half-dozen
pathogens of future concern as a health threat in drinking water, he said.
After growing pathogens in the lab, the researchers will add the pathogen-spiked
"cocktails" to pilot-scale drinking water treatment systems. The
approach will help them evaluate the ability of different treatment techniques
to remove the bugs.
The two pathogens of greatest concern
since 1980 have been giardia and crypto-sporidium. Both have caused major
health threats in the United States. The most serious was the 1993 cryptosporidium
outbreak in Milwaukee, in which 69 people died of complications arising
from the outbreak.
Harrington's team will take a forward-looking
view: Is there another emerging pathogen on the horizon that could unexpectedly
threaten public health, in the same way crypto has in the past decade?
"Cryptosporidium is not the
only microorganism of concern in drinking water," says Battigelli.
"Although crypto has been the industry buzzword since 1993, we are
finding other microorganisms which may also pose substantial risks to public
health if left unaddressed."
There is reason to suspect a "new
crypto" could be lurking, Harrington says. Since scientists have only
recently been able to accurately detect many of the waterborne pathogens
that cause illness, some newly-identified types may have been causing low
levels of disease for years.
That's true of several pathogens
in the study. A class of viruses called caliciviruses has been traced to
recent waterborne outbreaks in the United States. The bacterium escherichia
coli 0157:H7, has caused at least two waterborne outbreaks that affected
more than 300 people. In North and South America, the parasite cyclospora
has caused serious health problems for people relying on untreated drinking
water.
Battigelli noted that medical treatment
is not available for some diseases caused by these pathogens. In many cases,
people rely exclusively on their body's immune system to fight them off.
Mortality rates can be high among those with undeveloped or weakened immune
systems, such as the very young, the elderly, chemotherapy patients, AIDS
patients and transplant recipients.
In this project, the team will be
studying viruses 100 times smaller than crypto organisms which could more
easily pass through some water-treatment technology. Other pathogens can
be very resistant to the standard chemical treatment of chlorination.
The study will also help gauge performance
of new water treatment technologies, which are becoming increasingly sophisticated.
Those methods include dissolved air flotation and microfiltration. These
treatments are more effective and more costly.
The crypto threat has driven a public
willingness to pay for better and safer technologies, Harrington says. The
city of Kenosha is installing a microfiltration system for city water, and
the city of Milwaukee is upgrading its filters and installing ozonation.
Harrington emphasized that U.S. water-treatment
standards are very good, and that drinking water is generally quite safe.
Water utilities are required to have a multi-barrier approach to water treatment,
where more than one technology is used to remove microorganisms.
"We could look at thousands
of water samples before finding anything to worry about," he says.
"But the consequences of failing to remove pathogens can be very large.
We want to ensure there is minimal risk of public exposure."  | 
