Giardiasis, an illness that affects the digestive tract, is
caused by a microscopic parasite called
Giardia lamblia
. The parasite attaches itself to the lining of the small
intestines in humans, where it sabotages the body's absorption
of fats and carbohydrates from digested foods.
Giardia
is one of the chief causes of
diarrhea
in the United States, and is transmitted through contaminated
water. It can survive the normal amounts of chlorine used to purify
community water supplies, and can live for more than 2 months in
cold water. As few as 10 of the microscopic parasites in a glass of
water can cause a severe case of giardiasis in a human being who
drinks it.
Young kids are three times more likely to have giardiasis than
adults, which leads some experts to believe that our bodies
gradually develop some form of immunity to the parasite as we grow
older. But it isn't unusual for an entire family to have
giardiasis, with some family members having diarrhea, some just
crampy abdominal pains, and others with few or no symptoms.
Signs and Symptoms
It's estimated that between 1% and 20% of the U.S.
population has giardiasis, and this figure may be 20% or
higher in developing countries, where giardiasis is a major cause
of epidemic childhood diarrhea. But more than two thirds of people
who are infected may have no signs or symptoms of illness, even
though the parasite is living in their intestines.
When the parasite
does
cause symptoms, the illness usually begins with severe watery
diarrhea, without blood or mucus. Giardiasis affects the body's
ability to absorb fats from the diet, so the diarrhea contains
unabsorbed fats. That means that the diarrhea floats, is shiny, and
smells very bad.
Other symptoms include:
- abdominal cramps
- large amounts of intestinal gas
- an enlarged belly from the gas
- loss of appetite
- nausea and
vomiting
- sometimes a low-grade
fever
These symptoms may last for 5 to 7 days or longer. If they last
longer, a child may lose weight or show other signs of poor
nutrition.
Sometimes, after acute (or short-term) symptoms of giardiasis
pass, the disease begins a chronic (or more prolonged) phase.
Symptoms of chronic giardiasis include:
- periods of intestinal gas
- abdominal pain in the area above the navel
- poorly formed, "mushy" bowel movements (poop)
Prevention
Here are some ways to protect your family from
giardiasis:
- Drink only from water supplies that have been approved by
local health authorities.
- Bring your own water when you go camping or hiking, instead
of drinking from sources like mountain streams.
- Wash raw fruits and vegetables well before you eat them.
- Wash your hands well before you cook food for yourself or for
your family.
- Encourage your kids to wash their hands after every trip to
the bathroom and especially before eating. If someone in your
family has giardiasis, wash your hands often as you care for him
or her.
- Have your kids wash their hands well after handling anything
in "touch tanks" in aquariums, a potential source of
giardiasis.
- Have your water checked on a regular basis if it comes from a
well.
Also, it's questionable whether infants and toddlers still
in diapers should be sharing public pools. But certainly they
should
not
if they're having diarrhea or loose stools (poop).
Contagiousness
People and animals (mainly dogs and beavers) who have giardiasis
can pass the parasite in their stool. The stool can then
contaminate public water supplies, community swimming pools, and
"natural" water sources like mountain streams.
Uncooked foods
that have been rinsed in contaminated water may also spread the
infection.
In child-care centers or any facility caring for a group of
people, giardiasis can easily pass from person to person. At home,
an
infected family dog
with diarrhea may pass the parasite to human family members who
take care of the sick animal.
Diagnosis
Doctors confirm the diagnosis of giardiasis by taking stool
samples and sending them to the lab to be examined for
Giardia
parasites. Several samples may be needed before the parasites are
found.
For that reason the doctor may order a much more sensitive test
called the Enzyme-Linked ImmunoSorbent Assay or ELISA test.
Less often, doctors make the diagnosis by looking at the lining
of the small intestine with an instrument called an endoscope and
taking samples from inside the intestine to be sent to a
laboratory. This is done in more extreme cases, when a definite
cause for the diarrhea hasn't been found.
Treatment
Giardiasis is treated with prescription medicines that kill the
parasites. Treatment typically takes 5 to 7 days, and the medicine
is usually given as a liquid that your child can drink. Some of
these medicines may have side effects, so your doctor will tell you
what to watch for.
If your child has giardiasis and your doctor has prescribed
medication, be sure to give all doses on schedule for as long as
your doctor directs. This will help your child recover faster and
will kill parasites that might infect others in your family. Again,
encourage all family members to wash their hands frequently,
especially after using the bathroom and before eating.
A child who has diarrhea from giardiasis may lose too much fluid
in the stool and become dehydrated. Make sure the child drinks
plenty of fluids but no caffeinated beverages, because they make
the body lose water faster.
Ask the doctor before you give your child any nonprescription
drugs for cramps or diarrhea because these medicines may mask
symptoms and interfere with treatment.
Duration
The incubation period for giardiasis is 1 to 3 weeks after
exposure to the parasite. In most cases, treatment with 5 to 7 days
of antiparasitic medication will help kids recover within a
week's time. Medication also shortens the time that they're
contagious. If giardiasis isn't treated, symptoms can last up
to 6 weeks or longer.
When to Call the Doctor
Call the doctor whenever your child has:
- large amounts of diarrhea, especially if he or she also has a
fever and/or abdominal pain
- occasional, small episodes of diarrhea that continue for
several days, especially if appetite is poor, and your child is
either gradually losing weight or isn't gaining as much as
expected
Reviewed by:
Joel Klein, MD
Date reviewed: June 2008
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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