Collecting Specimens for Varicella Zoster Virus (VZV) Testing
Health care professionals: please follow these guidelines when collecting and shipping specimens for varicella zoster virus (VZV) testing. Review the video, which illustrates for collecting specimens. Complete and submit the specimen collection form and contact the CDC National VZV Laboratory with questions.
For more information about interpreting lab tests for VZV, see Interpreting Laboratory Tests.
Collecting and Shipping Blood for VZV Serologic Assays
There are two ways to prepare specimens of peripheral blood suitable for testing at CDC using VZV-specific serologic assays.
Second Method: Preparation of Serum from Whole Blood
- Collect whole venous peripheral blood in serum separator vacutainer tubes.
- Permit the specimen to fully clot by standing at room temperature for at least 30 minutes.
- After the clot has formed, tubes can be centrifuged at approximately 200 X g for 5 minutes.
- The clot will have passed to the bottom of the tube and the serum fraction will be at the top, with the separator plug as a barrier between the two fractions. The serum fraction can simply be aliquoted into sterile, 0-ring seal freezing tubes using a sterile pipet.
- Freeze serum specimens at –20°C.
Handling and Shipping
Collecting and Shipping Specimens for VZV PCR/Genotyping
To make a laboratory diagnosis of VZV infection using polymerase chain reaction (PCR) method, the presence of the virus DNA should be demonstrated in tissues, vesicular fluid, maculopapular lesions, or crusts from lesions. The following methods are recommended.
Polyester Swab Method
(best suited to sampling vesicular lesions)
- A sterile needle should be used to unroof the top of the vesicle.
- A sterile swab† is then used to vigorously swab the base of the lesion— applying enough pressure to collect epithelial cells without causing bleeding—and collect vesicular fluid. It is important to collect infected epithelial cells from the base of the lesion because they usually contain a significant amount of virus.
†We recommend swabs made from synthetic fibers, such as polyester, because it is difficult to elute virus from cotton swabs, and wooden swab supports usually absorb extraction buffer and inhibit PCR.
- Swabs must be placed individually into separate, empty tubes to avoid contamination. Place swabs directly into tubes. Do not place transport medium into the tube; the specimen MUST be kept dry. Tubes must be individually labeled and must be resistant to breakage.
- See Handling and Shipping PCR Specimens for shipping instructions.
Glass Slide Method
(This method is critical for the collection of material from maculopapular lesions)
- Rake the edge of the slide over the selected lesion, abrading the lesion with sufficient vigor to ensure that skin cells are gathered onto the slide. Use a sterile polyester swab to scrub the abraded lesion and (using the same swab) collect the material collected on the edge of the slide. Note: with young children, it may be less stressful if you ask them to help with this. If more than one lesion is sampled, a separate swab should be used for each one.
- Insert the swab into a tube and close it (many swabs are provided with a tube that includes a label for marking the specimen).
- Ship in a padded envelope. The swab for each sampled lesion must be placed in a separate swab tube, but multiple tubes can be shipped in the same envelope. Dry maculopapular lesion material is stable for several weeks at ambient temperature.
- See Handling and Shipping PCR Specimens for shipping instructions.
Collecting Crusts (Scabs)
Crusts are also excellent samples for PCR detection of VZV DNA. Crusts can be lifted off the skin (a glass slide is also useful for this purpose) and transferred directly into break-resistant, snap-cap or screw-top tubes. See Handling and Shipping PCR Specimens for shipping instructions.
Collecting Other Specimen Types
For some disease presentations with a suspected VZV etiology (e.g., meningitis, multi-focal organ damage), samples of cerebral spinal fluid (CSF), blood, or biopsy tissue may also be shipped. Blood or CSF can be shipped on cold packs or frozen. Biopsy tissue is preferred shipped frozen and, if available, unfixed. See Handling and Shipping PCR Specimens for additional shipping instructions.
Handling and Shipping PCR Specimens
In rare cases involving severe complications or death, other types of specimens (e.g., biopsied tissue, cerebrospinal fluid, peripheral blood, etc.) may be sent to the National VZV Laboratory for PCR testing. When possible, liquid specimens should be shipped frozen.
Sources of Suitable Supplies
- Freezing vials: 2.0 ml polypropylene vials are available from a number of companies, including Nalgene Labware (#5000-0020), Wheaton Science Products (#985916), Corning (#430659, 431386), and Nunc (#347627).
- Plastic re-sealable bags (for containment of blood spot pads and PCR swab tubes to reduce risk of cross-contamination): 8" × 8" or larger bags are available from Daigger & Company, Inc (#HX28281D) and Fisher Scientific (#01-816-1E).
- Swabs with tubes: a single-unit, polyester swab with tube and slide on cap is available from Epicentre Biotechnologies (#QEC091H). Suitable swab tubes are also available on request from the CDC National VZV Laboratory.
- Filter blot pads: these pads are made to custom specifications for the CDC National VZV Laboratory. On request, CDC will supply to local and state health departments and to the varicella surveillance project office in your area.
These items are available through distributors of scientific laboratory products, such as Fisher Scientific and WVR International.
Video of Specimen Collection Procedures
A 4-minute video, developed for health care professionals, illustrates the most appropriate procedures for collecting VZV skin lesions and blood specimens. See three options for downloading the video.
Form for Specimen Collection
Open the form, type text into the designated boxes, print and complete. Or download, print and complete the form. Send the 2-page form and specimen to CDC VZV Laboratory. Please follow shipping and handling guidelines, as outlined above.
Note: This information is duplicated on the lab page for shingles.
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