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Coccidioidomycosis Serology: Acid-Fast Stain of Stool (Qualitative)

Published: August 9, 2026Updated: August 17, 2026

This test checks for the presence of *Coccidioides* spores or fungal elements in your stool using an acid-fast staining method, which helps identify potential infection with the coccidioidomycosis fungus.

Quick summary

["This test may help diagnose suspected fungal infection if other tests are inconclusive or symptoms persist."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
10655-9
Short code
Coccidia Duod fl Acid fast Stn
Synonyms
Coccidia Duod fl Acid fast Stn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
acid-fast-stain
CPT
84484
SNOMED
302774002
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

When Is This Test Used?

Doctors may order this test if you have symptoms like fever, cough, fatigue, or weight loss, especially if you’ve lived in or traveled to regions where coccidioidomycosis is common (e.g., the southwestern U.S., parts of Latin America). It’s also used in cases where other tests for fungal infections are negative or when monitoring treatment response.

What Does the Test Involve?

A small sample of your stool is collected and examined under a microscope after staining. The test looks for acid-fast organisms (tiny fungal structures) that may indicate infection. Results are qualitative (positive or negative) rather than measuring exact amounts.

What to Expect Before the Test

No special preparation is needed. Bring your stool sample to the lab on the day of testing. If you’re taking antibiotics or antifungal medications, let your healthcare provider know, as this may affect results.

What Are Possible Results?

Positive result: The test detects acid-fast organisms, suggesting possible *Coccidioides* infection. Negative result: No organisms found, but this doesn’t rule out infection entirely—other tests or follow-up may be needed.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Stool AFB (Qualitative)

Frequently asked questions

Why might my doctor order this test?
Your doctor may recommend this test if you have symptoms of a fungal lung infection (e.g., persistent cough, chest pain) or if you’ve been exposed to areas with high coccidioidomycosis risk. It’s a simple way to check for fungal presence in stool, though it’s not always definitive.
What does a positive result mean?
A positive result suggests possible *Coccidioides* infection, but it doesn’t confirm the diagnosis alone. Your doctor may order additional tests (like blood or urine cultures) or other serology tests to confirm or rule out infection.
Can this test be used to monitor treatment?
This test is less commonly used for monitoring treatment because it’s qualitative and focuses on stool. More specific blood or urine tests (e.g., immunoassays) are typically preferred for tracking response to antifungal therapy.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy