Giardiasis is an illness that affects the digestive
tract (stomach and intestines). It's one of the top causes of diarrhea
in the United States.
What Causes Giardiasis?
Giardiasis (jee-are-DYE-uh-sis) is caused by the microscopic Giardia parasite.
The parasite attaches itself to the lining of the small intestines in humans, where
it causes diarrhea and interferes with the body's absorption of fats and carbohydrates
from digested foods.
Is Giardiasis Contagious?
Giardiasis is very contagious, and can spread easily among families. In childcare
centers or any facility caring for a group of people, or people who are traveling,
giardiasis can easily pass from person to person.
How Does Giardiasis Spread?
Giardiasis spreads through water or food contaminated with the stool (poop) of
someone who's infected. Animals (mainly dogs and beavers) who have giardiasis also
can pass the parasite in their stool. The stool can then contaminate public water
supplies, community swimming pools, and water sources like lakes and streams.
Uncooked foods that have been rinsed in contaminated water and surfaces contaminated
by stool (for instances, diaper pails and toilet handles) also can spread the infection.
The Giardia parasite 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 severe giardiasis
in a person who drinks it.
Who Gets Giardiasis?
In developing countries, giardiasis is a major cause of epidemic childhood diarrhea.
But even people in developed countries can get the infection, especially children
younger than 5.
Young kids are more likely to have giardiasis than adults. So some experts think
that our bodies gradually develop some form of immunity to the parasite as we get
older. But it isn't unusual for an entire family to be infected, with some family
members having diarrhea, some just crampy abdominal pains, and others with no symptoms.
What Are the Signs and Symptoms of Giardiasis?
Many people with giardiasis 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. 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.
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.
(or short-term) symptoms of giardiasis pass, the disease begins a
(or more lasting) phase. Symptoms of chronic giardiasis
periods of intestinal gas
belly pain in the area above the navel (belly button)
poorly formed, "mushy" bowel movements (poop)
How Is Giardiasis Diagnosed?
Doctors confirm the diagnosis of giardiasis by taking stool
samples that are checked for Giardia parasites. Several samples may be
needed before the parasites are found. For that reason, the doctor might order a much
more sensitive test, 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
and taking samples from inside the intestine to be checked in a lab. This
is done in more extreme cases, when a definite cause for the diarrhea hasn't been
How Is Giardiasis Treated?
Giardiasis is treated with prescription medicines that kill the parasites. Treatment
takes about 5 to 7 days, and the medicine is usually given as a liquid. Some of these
medicines may have side effects, so your doctor will tell you what to watch for.
If your child has giardiasis, 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. Encourage all family members to wash their
hands well and often, especially after using the bathroom and before eating.
A child who has diarrhea from giardiasis may lose too much fluid in the stool and
Make sure the child drinks plenty of liquids but no caffeinated beverages or juice,
as 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.
How Long Does Giardiasis Last?
In most cases, treatment with 5 to 7 days of antiparasitic medicine will help kids
recover within a week's time. Medicine also shortens the time that they're contagious.
If giardiasis isn't treated, symptoms can last up to 6 weeks or longer.
Can Giardiasis Be Prevented?
Some food safety and hygiene precautions can help prevent giardiasis. To help protect
Drink only from water supplies that have been approved by local health authorities.
Bring your own water when you go camping or hiking. Never drink from sources like
mountain streams. Or boil water for at least 10 minutes.