Varicella-Zoster Virus DFA
Also known as: VZVFA
Use
This test detects the presence of varicella-zoster virus (VZV) using a direct fluorescent antibody (DFA) technique. DFA sensitivity is highest when performed on scrapings from the base of lesions. It is used to diagnose infections caused by VZV, which is responsible for illnesses such as chickenpox and shingles. While DFA is reliable, molecular testing methods are generally preferred. This assay is only suitable when adequate cell samples are obtained from specimen collection.
Special Instructions
Collect vesicle specimens during the first three days of rash onset to ensure optimal sensitivity. Specimens should be transferred to viral transport media immediately and refrigerated due to temperature sensitivity. Specimen source information is preferred during the submission process.
Limitations
The sensitivity of the DFA method is dependent on specimen quality. If fewer than 20 cells are present, the result is reported as 'sample inadequate.' Bone marrow, CSF, or whole blood specimens, and certain types of swabs, are unacceptable, and inadequate samples should be referred for culture. DFA does not test for herpes simplex virus, which is found in approximately 20% of VZV-positive samples.
New York Approved
Methodology
Immunoassay (Immunofluorescent Stain)
Biomarkers
LOINC Codes
- 5882-6
- 31208-2
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Other
Volume
Not provided
Minimum Volume
Not provided
Collection Instructions
Swab should be rolled in base of fresh vesicle to obtain cells.
Patient Preparation
Collect vesicle specimen during first 3 days of rash.
Causes for Rejection
Bone marrow, CSF, or whole blood; calcium alginate, eSwab, dry or wood swabs.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 hours |
| Refrigerated | 72 hours |
| Frozen | Unacceptable |
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