Giardiasis is an
illness caused by Giardia lamblia, a one-celled, microscopic
parasite that lives in the intestines of people and animals. The parasite
is passed in the bowel movement of an infected person or animal. During
the past 15 years, Giardia lamblia has become recognized as one of
the most common causes of waterborne disease in humans in the United
States. This parasite is found in every region of the United States and
throughout the world.
What are the symptoms of
cramps, and nausea are the most common symptoms of giardiasis. These
symptoms may lead to weight loss and dehydration. However, not everyone
infected has symptoms.
How long after being infected
do symptoms appear?
Symptoms usually appear
1-2 weeks after infection with the parasite.
How long will I have symptoms?
In otherwise healthy
persons, symptoms may last 4-6 weeks. Occasionally, symptoms last longer.
How can I get
You can become infected
after accidentally ingesting (swallowing) the parasite. Giardia may
be found in soil, food, water, or on surfaces.
- By swallowing water
contaminated with Giardia. A person can swallow a Giardia
cyst, the infectious stage of the parasite, by swallowing water from
swimming pools, lakes, rivers, springs, ponds, or streams contaminated
with sewage or feces from humans or animals.
- By eating uncooked
food contaminated with Giardia. Thoroughly wash with safe water
all vegetables and fruits you plan to eat raw.
- By accidently
swallowing the parasite picked up from surfaces (i.e., toys, bathroom
fixtures, changing tables, diaper pails) contaminated with stool from
an infected person. Hands become contaminated by not following good
handwashing practices, particularly after using the toilet, changing
diapers, and before eating.
Who is at risk?
Persons at increased
risk for giardiasis include child care workers; diaper-aged children who
attend day care centers; international travelers; hikers; campers; and
others who drink untreated water from contaminated sources. Several
community-wide outbreaks of giardiasis have been linked to drinking
municipal water contaminated with Giardia.
What should I do if I think I
See your health care
How is a Giardia
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, your
health care provider may ask you to submit several stool specimens over
What is the treatment for
drugs are available to treat Giardia.
How can I prevent
- Wash hands with soap
and water after using the toilet, changing diapers, and before
- Avoid drinking water
or eating food that may be contaminated.
- Wash and peel all
raw vegetables and fruits before eating.
- Avoid drinking water
from lakes, rivers, springs, ponds, or streams unless it has been
filtered and chemically treated.
community-wide outbreaks caused by contaminated drinking water, boil
drinking water for 1 minute to kill the Giardia parasite and
make the water safe to drink.
- When traveling in
countries where the water supply may be unsafe, avoid drinking
unboiled tap water and avoid uncooked foods washed with unboiled tap
water. Bottled or canned carbonated beverages, seltzers, pasteurized
fruit drinks, and steaming hot coffee and tea are safe to drink.
- If you work in a
child care center where you change diapers, be sure to wash your hands
thoroughly with soap and warm water after every diaper change, even if
you wear gloves.
- If you or your child
has Giardia, avoid swimming in pools for 2 weeks after the
diarrhea or loose stools have cleared. Giardia cysts are fairly
chlorine resistant and are passed in the stools of infected people for
several weeks after they no longer have symptoms.
My water comes from a well;
should I have my well water tested?
Consider having your
well water tested if you answer yes to the following questions:
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
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 instead of Giardia.
Although fecal coliform tests do not specifically test for Giardia,
testing will show if your well has fecal contamination. If it does, 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.
My child was recently diagnosed
as having giardiasis, but does not have any diarrhea. My health care
provider says treatment is not necessary. Is this true?
In general, the answer
supported 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
For more information:
- Addiss DG, Juranek
DD, Spencer HC. Treatment of children with asymptomatic and
nondiarrheal Giardia infection. Pediatr Infect Dis J
- Addiss DG, Davis JP,
Roberts JM, Mast EE. Epidemiology of giardiasis in Wisconsin.
Increasing incidence of reported cases and unexplained seasonal
trends. Am J Trop Med Hyg 1992;47:13-9.
- Bartlett AV,
Englander SJ, Jarvis BA, Ludwig L, Carlson JF, Topping JP. Controlled
trial of Giardia lamblia: Control strategies in day care
centers. Am J Public Health 1991;81:1001-6.
- Kreuter AK, Del Bene
VE, Amstey MS. Giardiasis in pregnancy. Am J Obstet Gynecol
DG, Juranek DD. Severe giardiasis in the United States. Clin Infect
Dis 1994; 18:760-3.
RW, Reid S,
Cheng T, et al. Recurrent outbreaks of giardiasis in a child day care
center, Wisconsin. Am J Public Health 1989;79:485-90.
This fact sheet is for
information only and is not meant to be used for self-diagnosis or as a
substitute for consultation with a health care provider. If you have any
questions about the disease described above or think that you may have a
parasitic infection, consult a health care provider.