Exam Overview

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 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 swallowed 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 gastrointestinal (GI) symptoms, results of the physical exam are generally normal for people with giardiasis. But some weight loss [up to 10 lb (4.5 kg) or more] is common.

Diarrhea that has lasted more 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.

What To Think About

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 cause infection.

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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