Collecting Specimens for Varicella Zoster Virus (Chickenpox & Shingles) Testing
Healthcare 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 shingles, see Interpreting Laboratory Tests.
- Prick the subject’s finger, using a lancet.
- Collect a sufficient quantity of blood onto both of the defined areas on the filter strip so that the spot expands to the circular border. Filter strips will be made available to state and local public health laboratories and to the varicella surveillance project office in your area on request.
- Permit the specimen to air dry completely. Do not allow strips to come into contact with each other while wet.
- Once the blood specimen has completely dried, place each filter strip in a separate sealable plastic bag. Important: Specimens must be permitted to air dry completely before placing each filter strip inside a separate sealable plastic bag. Otherwise, bacterial or fungal growth can occur, destroying the specimen.
Handling and Shipping
- Dried blood specimens should be stored at ambient temperature. There is no need to refrigerate or freeze specimens prepared in this fashion.
- Specimens should be mailed to the laboratory by regular postal service (unless a result is urgently required) at the earliest opportunity.
- 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
- Ship specimens by overnight mail on sufficient dry ice to keep them frozen for 3 days.
- Frozen specimens obtained for larger studies may be kept indefinitely at –20°C, accumulated, and sent in batches to CDC, depending on preference.
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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
- Dried specimens for PCR can be stored at ambient temperature indefinitely, although we prefer to receive specimens as soon after collection as possible.
- Do not refrigerate or freeze dry specimens intended for testing by PCR. Specimens can be mailed by regular post unless a result is urgently required. Do not suspend specimens in transport medium: they should be shipped dry.
In rare cases involving severe complications or death, other types of specimens (e.g., biopsied tissue, CSF, peripheral blood, etc.) may be sent to the CDC National VZV Laboratory for PCR testing. When possible, liquid specimens should be shipped frozen.
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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
This 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 4-minute video.
- Quick compressed [2MB] (compressed for quick download)
- Compressed Broadbrand Video [14MB] (higher quality, non-compressed for BroadBand or local computer use)
- Non-compressed DSL [16MB] (highest quality, non-compressed for those connecting via DSL or accessing via a local area network)
Script of Video
This video outlines procedures for collecting varicella skin lesions and blood specimens. Skin lesions are the preferable method for laboratory confirmation of varicella. Blood specimens should be used to test for varicella immunity.
There are 3 types of lesions you will see most often resulting from varicella zoster virus: a scabbed or crusted lesion; a maculopapular lesion, which is a lesion with a raised red bump; or a vesicular lesion, which is a blister-like or fluid-filled lesion.
To collect a scab for varicella zoster virus testing, begin by gently lifting the scab from the lesion. Once the scab is collected, place it in a container such as a swab specimen tube or a plastic baggie. If there is more than one scab, place each scab individually in different containers.
The most effective technique for collecting cells from a maculopapular lesion or fluid from a vesicular lesion is the same, though for maculopapular lesions it is a greater challenge to ensure that enough skin cells are collected. Lesions in vaccinated individuals are likely to be atypical, macular only or papular only, but obtaining specimens from papular lesions is possible using the following technique. Use the edge of a clean slide to loosen and collect skin cells or fluid from the lesion as shown here. Then, using a sterile swab, rub the lesion vigorously enough to ensure that skin cells or fluid are collected. To ensure an adequate amount of skin cells is collected, particularly with maculopapular lesions, we recommend also using the swab to wipe the skin cells off the edge of the slide used to scrape the lesion. You may also press the slide directly to the lesion to collect skin cells or fluid as shown here. This technique is especially effective for vesicles where a "smudge" should be visible. To ensure that skin cells or fluid are on the slide, compare it to a clear slide under light, as shown here.**
To collect a blood specimen for varicella immunity testing perform a finger stick on the individual. Soak the circle on the filter paper with blood ensuring that the circle is completely full and check to see that blood has soaked through to the other side. Then soak the remaining circle, and again ensure that blood has soaked through both sides of the filter paper. Allow the blood to dry before packaging the filter paper. Venipuncture is also an acceptable method for blood collection. Collect at least 1 ml of blood into a serum-separator vaccutainer tube. Before storage or shipping, separate the serum from the cells in a centrifuge for 15 minutes.
For more information on varicella zoster virus specimen collection, storage, and handling, please contact the Centers for Disease Control and Prevention, National Varicella Laboratory, 1600 Clifton Road, NE, MS G-18, Atlanta, GA 30333. Telephone 404-639-3667; fax 404-639-4056; email email@example.com.
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 National VZV Laboratory. Please follow shipping and handling guidelines, as outlined above.Top of Page
Note: This information is duplicated on the lab page for chickenpox.
Shingles (Herpes Zoster) Diagnosis & Testing
Overview of testing methods for clinical diagnosis
Slide set: Varicella and Breakthrough Varicella: To Test or Not to Test [2.07MB, 14 slides]
MS PowerPoint® file available upon email request
- Page last reviewed: May 1, 2014
- Page last updated: May 1, 2014
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