Medical history and physical exam for giardiasis

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Exam Overview

A standard physical exam is usually performed when giardiasis is suspected. Some doctors include a rectal exam, including a preliminary stool sample. But for stool analysis, the person usually needs to collect a stool sample. The stool sample can often be taken at home and then returned to the doctor for evaluation.

The medical history will include questions about recent possible exposure, including:

• When the symptoms started, what they are, and how long they have lasted.
• In children, about any noticeable weight loss, lack of appetite, or failure to gain weight or grow normally.
• Whether you have drunk any untreated water from rivers, lakes, or streams—especially during travel to a region where G. lamblia is common. Even eating fruit that has been washed in untreated water or brushing teeth with untreated water can be enough to cause infection.
• Whether you have been swimming in natural or treated water.
• Whether you live or work in a nursing home or other custodial care facility, or are a family member of an employee.
• Whether you or a family member works in (or your child regularly attends) a day care center, especially if many of the children are not yet toilet trained.
• Whether you have had oral-anal or oral-genital contact with an infected person.

Why It Is Done

The medical history and physical exam are done to evaluate possible symptoms of giardiasis, especially persistent diarrhea.

Results

Except for diarrhea and other symptoms, results of the physical exam are generally normal when giardiasis is present. But some weight loss [up to or more] is common.

Diarrhea that has lasted more than 7 to 10 days usually suggests giardiasis, especially if there are signs of poor absorption of nutrients by the intestine. These include flatulence, burping, lactose intolerance, or greasy stools.

Most lab tests are also usually normal. Blood levels of carotene (a form of vitamin A) and folic acid (a B vitamin) may be low, and urinary excretion of vitamin B₁₂ after administration of a test dose may also 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.

What To Think About

Since the onset of symptoms can occur long after exposure, the medical history is especially important. Even very small amounts of untreated water can contain enough Giardia lamblia to cause infection, so any possible exposures may be notable.

Exposure to Giardia lamblia through day care or nursing home employees may be more difficult to recall or link to the start of symptoms.

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Last updated:	October 19, 2005
Author:	Colleen Cronin
Reviewed By:	Adam Husney, MD - Family Medicine, W. David Colby, MSc, MD, FRCPC - Infectious Disease
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer