Toxicity Screening for Giardia lamblia (Serum/Plasma Immunoassay)

Your healthcare provider may order this test if you have symptoms that suggest a recent or past infection, if you were exposed to someone who tested positive, or if it is important to know whether your immune system has produced antibodies. The results can help guide diagnosis, treatment decisions, and any follow-up care you may need.

Your healthcare provider may recommend this test if you’ve had symptoms like persistent diarrhea, stomach cramps, bloating, or nausea—especially if you’ve traveled to areas with poor sanitation or consumed contaminated water. It can also be used to confirm a suspected Giardia infection in people with ongoing digestive problems.

Before the test, tell your provider about any medications, supplements, or recent illnesses, since some of these can affect the results. In most cases, no special preparation such as fasting is required. A small blood sample will be drawn, usually from a vein in your arm, and the procedure typically takes only a few minutes.

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. The test looks for antibodies (proteins your immune system makes) that could signal past or current Giardia exposure.

Your results will be reported as either positive or negative. A positive result means antibodies were detected in your blood, which usually indicates exposure to the infection at some point in the past. A negative result means no antibodies were found, although it can take days to weeks for antibodies to appear after an infection.

A positive result means your body has detected Giardia antibodies, which may suggest you’ve been infected. A negative result means no detectable antibodies were found, but this doesn’t rule out a past infection. Results are qualitative (yes/no) and don’t provide a timeline for when infection occurred.

A positive result most often reflects a previous infection that your immune system has already fought off. It can also occur after vaccination, because vaccines teach your body to make antibodies. Less commonly, a positive result may come from cross-reactivity with antibodies from a similar infection, or in rare cases from a laboratory error.

Giardia is spread through contaminated food, water, or contact with infected people. Symptoms may appear weeks after exposure and can include watery diarrhea, gas, nausea, or fatigue. Antibodies can stay in your system for months or years after infection.