Despite its highly technical name, the enzyme-immuno assay (EIA) for Chlamydia is fairly easy to understand. It’s one of about five tests commonly used today to detect Chlamydia infections.

And as far as STD testing goes, the EIA is pretty important: about 2.8 million Americans get Chlamydia each year. Here’s what you need to know about the enzyme-immuno assay (EIA) test to stay healthy.

Antigens, Antibodies, and Enzyme-Immuno Assays (EIA)

Baiting a hook to catch a fish works for roughly the same reason enzyme-immuno assays (EIA) work as Chlamydia tests.

• You provide a cell sample: In order to see whether you have Chlamydia, a doctor takes a sample from the affected area of the body, usually the genitals.
• The test contains Chlamydia antibodies: Think of these as the fish. These are the “good guys” and work by linking to and neutralizing the Chlamydia antigens the disease spreads.
• The sample and solution combine: Think of Chlamydia antigens as bait. If they’re present in your sample, the antibodies (fish) will latch onto them right away. If this chemical reaction happens, the test fluid indicates as much, often with a color change.

This particular Chlamydia test was first developed as a quicker and cheaper alternative to culture tests, which can take several days to show results. The EIA Chlamydia test can provide feedback in 24 hours, which allows people to get treatment faster.