Giardiasis
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Giardiasis (GEE-are-DYE-uh-sis) is a diarrheal illness caused by Giardia
intestinalis (also known as Giardia lamblia), a one-celled,
microscopic parasite that lives in the intestine of people and animals.
The parasite is passed in the stool of an infected person or animal.
The parasite is protected by an outer shell that allows it to survive
outside the body and in the environment for long periods of time. During
the past 2 decades, Giardia has become recognized as one of the
most common causes of waterborne disease (drinking and recreational)
in humans in the United States. The parasite is found in every region
of the United States and throughout the world.
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Symptoms include diarrhea, loose or watery stool, stomach cramps, and
upset stomach. These symptoms may lead to weight loss and dehydration.
Some people have no symptoms.
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Symptoms generally begin 1-2 weeks after being infected.
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In otherwise healthy persons, symptoms may last 2-6 weeks. Occasionally,
symptoms last longer.
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Giardia lives in the intestine of infected humans or animals. Millions
of germs can be released in a bowel movement from an infected human or
animal. You can become infected after accidentally swallowing the parasite. Giardia may
be found in soil, food, water, or surfaces that have been contaminated
with the feces from infected humans or animals. Giardia is not spread
by contact with blood. Giardia can be spread:
- By putting something in your mouth or accidentally swallowing something
that has come in contact with the stool of a person or animal infected
with Giardia.
- By swallowing recreational water contaminated with Giardia.
Recreational water is water in swimming pools, hot tubs, jacuzzis, fountains,
lakes, rivers, springs, ponds, or streams that can be contaminated with
sewage or feces from humans or animals.
- By eating uncooked food contaminated with Giardia. Thoroughly
wash with uncontaminated water all vegetables and fruits you plan to
eat raw. See below for information on making water safe.
- By accidentally swallowing Giardia picked up from surfaces (such
as toys, bathroom fixtures, changing tables, diaper pails) contaminated
with stool from an infected person.
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Everyone. Persons at increased risk for giardiasis include child care
workers; children who attend day care centers, including diaper-aged children;
international travelers; hikers; campers, swimmers; and others who drink
or accidentally swallow water from contaminated sources that is untreated
(no heat inactivation, filtration, or chemical disinfection). Several community-wide
outbreaks of giardiasis have been linked to drinking municipal water or
recreational water contaminated with Giardia.
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Yes, Giardia can be very contagious. Follow these guidelines to
avoid spreading Giardia to others.
- Wash your hands with soap and water after using the toilet, changing
diapers, and before eating or preparing food.
- Avoid swimming in recreational water (pools, hot tubs, lakes or rivers,
the ocean, etc.) if you have Giardia and for at least 2 weeks
after diarrhea stops. You can pass Giardia in your stool and contaminate
water for several weeks after your symptoms have ended. This has resulted
in outbreaks of Giardia among recreational water users.
- Avoid fecal exposure during sex.
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See your health care provider.
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Your health care provider will likely ask you to submit stool samples
to see if you have the parasite. Because Giardia can be difficult
to diagnose, he or she may ask you to submit several stool specimens over
several days.
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Several prescription drugs are available to treat Giardia. Consult
with your health care provider. Although Giardia can infect all
people, young children and pregnant women may be more susceptible to the
dehydration resulting from diarrhea and should drink plenty of fluids while
ill.
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Practice good hygiene.
- Wash hands thoroughly with soap and water.
a. Wash hands after using the toilet and before handling or eating
food (especially for persons with diarrhea).
b. Wash hands after every diaper change, especially if you work
with diaper-aged children, even if you are wearing gloves.
- Protect others by not swimming if experiencing diarrhea (essential
for children in diapers).
Avoid water that might be contaminated.
- Avoid swallowing recreational water.
- Avoid drinking untreated water from shallow wells, lakes, rivers, springs,
ponds, and streams.
- Avoid drinking untreated water during community-wide outbreaks of disease
caused by contaminated drinking water. In the United States, nationally
distributed brands of bottled or canned carbonated soft drinks are safe
to drink. Commercially packaged noncarbonated soft drinks and fruit juices
that do not require refrigeration until after they are opened (those
that are stored unrefrigerated on grocery shelves) also are safe.
- Avoid using ice or drinking untreated water when traveling in countries
where the water supply might be unsafe.
- If you are unable to avoid drinking or using water that might be contaminated,
then treat the water yourself by:
Heating the water to a rolling boil for at least 1 minute.
OR
Using a filter that has an absolute pore size of at least 1 micron
or one that has been NSF rated for "cyst removal."
If the methods above cannot be used, then try chemical inactivation
of Giardia by chlorination or iodination. Chemical disinfection
may be less effective than other methods because it is highly dependent
on the temperature, pH, and cloudiness of the water.
Avoid food that might be contaminated.
- Wash and/or peel all raw vegetables and fruits before eating.
- Use uncontaminated water to wash all food that is to be eaten raw.
- Avoid eating uncooked foods when traveling in countries with minimal
water treatment and sanitation systems.
Avoid fecal exposure during sex.
My water comes from a well; should I have my well water tested?
If you answer yes to the following questions, consider having your well
water tested.
- Are other members of your family or users of your well water ill?
If yes, your well may be the source of infection.
- Is your well located at the bottom of a hill or is it considered
shallow?
If so, runoff from rain or flood water may be draining directly into
your well causing contamination.
- Is your well in a rural area where animals graze?
Well water can become fecally contaminated if animal waste seepage contaminates
the ground water. This can occur if your well has cracked casings, is
poorly constructed, or is too shallow.
Tests specifically for Giardia are expensive, difficult, and usually
require hundreds of gallons of water to be pumped through a filter. If
you answered yes to the above questions, consider testing your well for
fecal coliforms or E. coli instead of Giardia. Although fecal
coliforms or E. coli tests do not specifically test for Giardia,
testing will show if your well has fecal contamination.
These tests are only useful if your well is not routinely disinfected
with chlorine since chlorine kills fecal coliforms and E. coli.
If the tests are positive, the water may also be contaminated with Giardia,
as well as other harmful bacteria and viruses. Look in your local telephone
directory for a laboratory or cooperative extension that offers water
testing. If the fecal coliform test comes back positive, indicating
that your well is fecally contaminated, contact your local water authority
for instructions on how to disinfect your well.
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In general, the answer by the American Academy of Pediatrics is that treatment
is not necessary. However, there are a few exceptions. If your child does
not have diarrhea, but is having nausea, or is fatigued, losing weight,
or has a poor appetite, you and your health care provider may wish to consider
treatment. If your child attends a day care center where an outbreak is
continuing to occur despite efforts to control it, screening and treatment
of children without obvious symptoms may be a good idea. The same is true
if several family members are ill, or if a family member is pregnant and
therefore not able to take the most effective anti-Giardia medications.
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