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Cryptosporidium
A 1993 outbreak of
cryptosporidium in Milwaukee affected more than 400,000 residents and caused
more than 100 deaths.
Symptoms can be month-long
bouts of diarrhea and vomiting along with dehydration. Other virulent
pathogens have also intruded into municipal water supplies with alarming
frequency. Contamination occurs when animal feces that contain
cryptosporidium are washed into municipal water supplies. This means
that people supplied with water from surface sources, such as rivers and
lakes, are more at risk. Approximately 61% of the U.S. population gets
water from surface sources, according to the American Water Works
Association.
Another waterborne parasite is giardia lamblia. Doctors
suggest that giardia is the most frequent cause of non-bacterial diarrhea in
North America with an attack rate three times as high for children as
adults. This disease is better known as “beaver fever.” Both giardia
and cryptosporidium are the cyst of a protozoan that lives in the intestinal
tract of infected mammals.
The best-known method for ridding municipal water supplies of
these contaminants is a combination of disinfection and filtration. Chlorine
itself does NOT effectively kill either of these virulent cysts. Currently
more than 20 million Americans receive unfiltered surface water. The
Center for Disease Control has had difficulty in determining an accurate
number of illnesses related to these parasites since doctors often dismiss
the complications as symptoms of influenza.
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