A standard physical exam is usually done when
giardiasis is suspected. Some doctors include a rectal
exam. A stool analysis often is done to look for signs of the parasite. The
stool sample can often be collected at home and then returned to the doctor for
The medical history will include questions about recent possible
The medical history and physical exam are done to evaluate possible
symptoms of giardiasis, especially persistent diarrhea.
Except for diarrhea and other gastrointestinal (GI) symptoms,
results of the physical exam are generally normal for people who have giardiasis.
But some weight loss [up to
10 lb (4.5 kg) or more] is
Diarrhea that has lasted longer than 7 to 10 days usually suggests
giardiasis, especially if there are signs that the intestine is not absorbing
nutrients properly. These signs include passing a large amount of gas,
excessive burping, lactose intolerance, or passing greasy stools.
Lab test results are usually normal. Blood levels of carotene (a
form of vitamin A) and folic acid (a B vitamin) may be low. But these can be
reversed quickly with treatment.
Symptoms that are not typical of giardiasis may be caused by
other intestinal infections or conditions. Depending
on the specific symptoms and medical history, additional tests may be done to
evaluate other possible causes of diarrhea.
Symptoms can start to occur long after exposure, so be sure to tell
your doctor if you may have swallowed untreated water. Even very small amounts
of untreated water can contain enough Giardia lamblia to
Exposure to Giardia lamblia through day care
or nursing home employees may be more difficult to remember or link to the
start of symptoms.
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September 9, 2011
E. Gregory Thompson, MD - Internal Medicine
& W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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