Microbiological Drinking Water Parameters - The Drinking Water - page 116

Three prescription drugs are available in the United States to treat giardia-
sis: quinacrine, metronidazole, and furazolidone. In a recent review of drug
trials in which the efficacies of these drugs were compared, quinacrine pro-
duced a cure in 93% of patients, metronidazole cured 92%, and furazolidone
cured about 84% of patients (Davidson, 1984). Quinacrine is generally the
least expensive of the anti- Giardia medications, but it often causes vomiting
in children younger than 5 years old. Although the treatment of giardiasis
is not an FDA-approved indication for metronidazole, the drug is commonly
used for this purpose. Furazolidone is the least effective of the three drugs
but is the only anti- Giardia medication that comes in liquid preparation,
which makes it easier to deliver the exact dose to small children who have
difficulty taking pills.
DID YoU KNoW?
Anyone who consumes contaminated food or water is at risk of
contracting giardiasis. This includes those drinking contaminated
water while camping or traveling, childcare workers, young chil-
dren who attend daycare centers, persons exposed to human feces
by sexual contact, and caregivers who might be coming in con-
tact with feces while caring for a person infected with giardiasis.
Children are especially susceptible because they put so many things
into their mouths.
Giardiasis occurs worldwide. In the United States, Giardia is the parasite
most commonly identified in stool specimens submitted to state laborato-
ries for parasitologic examination. Over a 3-year period, approximately 4%
of 1 million stool specimens submitted to state laboratories tested positive
for Giardia (CDC, 1979). Other surveys have demonstrated Giardia prevalence
rates ranging from 1 to 20%, depending on the location and ages of persons
studied. Giardiasis ranks among the top 20 infectious diseases that cause the
greatest morbidity in Africa, Asia, and Latin America (Walsh and Warren,
1979); it has been estimated that about 2 million infections occur per year in
these regions (Walsh, 1981).
People who are at highest risk for acquiring Giardia infection in the United
States may be placed into five major categories:
1. People in cities whose drinking water originates from streams or riv-
ers and whose water treatment process does not include filtration, or
where filtration is ineffective because of malfunctioning equipment
2. Hikers, campers, and people who enjoy the outdoors
3. International travelers