Environmental Engineering Reference
In-Depth Information
99.9% removal or inactivation of Giardia . This regulation requires that all
drinking water systems using surface water or groundwater under the direct
influence of surface water must disinfect and filter the water. The Enhanced
Surface Water Treatment Rule (ESWTR), which includes Cryptosporidium and
further regulates Giardia , was established in 1996.
Giardiasis*
Giardiasis is recognized as one of the most frequently occurring waterborne
diseases in the United States, where Giardia lamblia cysts have been discovered
in places as far apart as Estes Park, Colorado (near the Continental Divide);
Missoula, Montana; Wilkes-Barre, Scranton, and Hazleton, Pennsylvania;
and Pittsfield and Lawrence, Massachusetts, to name just a few.
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Symptoms of giardiasis generally appear 7 to 10 days after the
organism is ingested.
Giardiasis is characterized by intestinal symptoms that usually last a week
or more and may be accompanied by one or more of the following: diarrhea,
abdominal cramps, bloating, flatulence, fatigue, and weight loss. Although
vomiting and fever are commonly listed as relatively frequent symptoms,
they have not been commonly reported by people involved in waterborne
outbreaks in the United States. Although most Giardia infections persist only
for 1 or 2 months, some people experience a more chronic phase that can
follow the acute phase or may manifest without an antecedent acute illness.
The chronic phase is characterized by loose stools and increased abdominal
gassiness with cramping, flatulence, and burping. Fever is not common, but
malaise, fatigue, and depression many ensue. For a small number of people,
the persistence of infection is associated with the development of marked
malabsorption and weight loss. Similarly, lactose (milk) intolerance can be
a problem for some people. This can develop coincidentally with the infec-
tion or be aggravated by it, causing an increase in intestinal symptoms after
ingestion of milk products (Weller, 1985).
Some people may have several of these symptoms without evidence of
diarrhea or have only sporadic episodes of diarrhea every 3 or 4 days. Still
others may not have any symptoms at all. The problem, then, may not be
one of determining whether or not someone is infected with the parasite but
how harmoniously the host and the parasite can live together. When such
harmony does not exist or is lost, it then becomes a problem of how to get rid
of the parasite, either spontaneously or by treatment.
* This section is adapted from Juranek, D.D., Giardiasis , U.S. Centers for Disease Control and
Prevention, Atlanta, GA, 1995.
 
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