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Lab test

Coccidioides Antibodies (IgG, IgM), Immunodiffusion Test

This test measures antibodies to two Coccidioides antigens, TP and F, in a blood serum sample. Quest describes these antibodies as forming in response to infection with the fungus that causes coccidioidomycosis.

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About this test

The test uses immunodiffusion, a laboratory method that detects antibodies to Coccidioides TP and F antigens, on a serum sample. Quest describes detection of these antibodies as playing an important role in identifying people with coccidioidomycosis, a fungal infection.

Quest describes the two antibodies as having different time courses: antibodies to the TP antigen usually appear during the first week of infection and remain detectable for about five months, and their presence is associated with recent, active infection, while antibodies to the F antigen appear within a month and can remain detectable for up to a year.

Who might consider this test?

  • Typically being evaluated by a clinician for possible coccidioidomycosis
  • The antibody pattern helps a clinician judge whether an infection is likely recent or longer-standing

Test details

CollectionQuest patient service center

Quest resources

Additional details

What this test looks at

The test reports two separate antibody results, one for the F antigen (IgG) and one for the TP antigen (IgM), both measured by immunodiffusion on a serum sample.

This test isn't part of the Celio Health store at the moment, so it can't be ordered or requested here. The test menu lists everything that can.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does this test measure?

It measures antibodies to two Coccidioides antigens, TP and F, in a serum sample, using immunodiffusion. These antibodies form in response to infection with the fungus that causes coccidioidomycosis.

How is the sample collected?

The test uses a 0.5 mL serum sample from a routine blood draw.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

Can this test tell how recent an infection is?

Quest describes the two antibodies as following different timelines: TP-antigen antibodies are associated with recent, active infection and are detectable for about five months, while F-antigen antibodies can remain detectable for up to a year, which can help a clinician read the overall pattern.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.