Serum or Plasma Test for Giardia duodenalis Antigen (Qualitative or Semi-Quantitative)

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms of Giardia infection, such as persistent diarrhea, nausea, or unexplained stomach discomfort. It could also be used to diagnose suspected exposure to Giardia, especially after travel to areas with poor sanitation, or in cases of recurrent gastrointestinal issues that don’t improve with other treatments.

What to Expect Before the Test

No special preparation is usually needed. You may provide a blood sample (serum or plasma) or other bodily fluid depending on the test type. If you’re taking antibiotics or other medications, let your provider know, as they might affect results.

What the Test Results Mean

A positive result indicates the presence of Giardia antigens, suggesting an active infection. A negative result means no detectable antigens were found, but it doesn’t rule out past infection. Follow-up testing or additional samples may be needed for confirmation.

Common Symptoms of Giardia Infection

Giardia can cause a range of symptoms, including chronic diarrhea, watery or fatty stools, abdominal pain, bloating, gas, nausea, and sometimes weight loss. Some people may have no symptoms at all, but the infection can still spread.