Serum or plasma concentration of a recent contact-specific antibody (e.g., IgG) to a pathogen, measured as a qualitative or semi-quantitative test

What This Test Measures

This test detects the presence of antibodies (such as IgG) that your immune system produces after exposure to a pathogen. Antibodies are proteins your body makes to fight off infections. The test is qualitative, meaning it only tells you if antibodies are present, not how much. It’s often used to trace recent exposures in public health settings.

Why It’s Done

Healthcare providers or public health agencies may order this test during outbreaks, after potential exposure to a contagious illness, or as part of contact tracing efforts. It helps identify individuals who may have been exposed but are not yet showing symptoms.

How It’s Performed

A blood sample is drawn from a vein in your arm. The sample is then tested in a lab using an immunoassay method (such as enzyme-linked immunosorbent assay, or ELISA), which detects specific antibodies against the pathogen of interest.

What to Expect Before the Test

There are no special preparations needed for this test. You can eat, drink, or take medications as usual on the day of your appointment. If you’re on blood-thinning medication, let your healthcare provider know before the test.