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Assay Sheet

Test ID

9500 Varicella-Zoster Virus (VZV) Real-time qPCR

CPT Code

Clinical Utility

VZV reactivation is commonly seen in immunocompromised individuals. These patients are more likely to have disseminated disease with extensive skin lesions, pneumonia, hepatitis, or encephalitis. Proper management is dependent upon early diagnosis; quantitative DNA PCR is a rapid and sensitive tool useful for detecting the virus, tracking the course of the infection, and monitoring response to treatment.

Procedure

Extraction of varicella-zoster viral DNA from plasma, CSF, other biological fluids, or tissues followed by amplification and detection using real-time, quantitative PCR. An internal control is added to ensure the extraction was performed correctly and the PCR reaction was not inhibited.

Specimens

Whole Blood: 3 to 5 ml collected in EDTA (lavender top) tube. Do not freeze; ship ambient. Testing will be performed on plasma separated from the submitted whole blood specimen. Whole blood specimens are accepted as a matter of convenience for the originating laboratory. 

Plasma: 3 to 5 ml separated from whole blood collected in EDTA (lavender top) tube; ship ambient.

Amniotic Fluid: 1 ml minimum, submitted in sterile, screw-top tube; ship ambient.

Bone Marrow: 2 ml minimum, collected in an EDTA (lavender top) tube. Do not freeze; ship ambient.

Bronchial Lavage/Bronchial Wash: 1 to 3 ml, collected in sterile, screw-cap tube; ship ambient.

Conjunctival/Eye Swab: Swab the conjunctiva with sterile swab and place in 1 to 2 ml sterile saline, M4, or viral transport media; ship ambient.

CSF: 1 ml minimum, submitted in sterile, screw-cap tube; ship on dry ice.

Pleural Fluid: 1 ml submitted in a sterile, screw-top tube; ship ambient.

Skin Swab: Sterile swab placed in 1 to 2 ml sterile saline, M4, or viral transport media in a sterile, screw-cap tube; ship ambient. Do not use calcium alginate swab or wood shafted swab.

Throat Gargle:  Instruct patient to gargle with 2 to 3ml sterile saline.  Expectorate into sterile cup, then transfer contents to sterile, screw-cap tube for shipment; ship ambient.  

Tissue: Place in a sterile, screw-cap tube, add a small amount of saline to keep moist. Prefer 1 mm x 1 mm specimen. Prefer fresh over formalin fixed for maximum sensitivity; ship ambient.

Upper respiratory aspirate (NP aspirate, nasal aspirate, tracheal aspirate, etc.): Instill 1 to 2 ml sterile saline into desired location and gently aspirate contents. Place collected fluid into sterile, screw-cap tube; ship ambient.

Upper respiratory swab (NP swab, throat swab): Swab desired location with sterile, flexible shaft swab, preferably a flocked swab. Place swab into 1 to 2 ml sterile saline, M4, or viral transport media in sterile, screw-cap tube. Do not use calcium alginate swab or wood shafted swab; ship ambient.

Vitreous Fluid: Place collected vitreous fluid into small, sterile, screw-cap tube; ship ambient.

Other specimens may be accepted for testing; however the following comment will appear in the final report: "The clinical utility of this result has not yet been demonstrated in the peer reviewed literature and is therefore unknown." Call ViraCor for further information.

Causes for rejection

Whole blood frozen. Call ViraCor at 800-305-5198 if specimen is greater than 96 hrs old

Specificity

The primers and probes used in this assay are specific for VZV based on similarity search algorithms. Additionally, no cross reactivity was detected when tested against adenoviruses, BKV, CMV, EBV, HSV-1, HSV-2, HHV-6 variant A, HHV-6 variant B, HHV-7, HHV-8, JCV, parvovirus B19, and SV-40.

Varicella-Zoster Virus Assay Range

100 copies/ml to 1 x 10¹⁰ copies/ml

Turnaround Time

Same day (within 8 to 12 hours of receiving specimen), Monday through Saturday

Shipping

ViraCor Laboratories, 1001 NW Technology Dr, Lee's Summit, MO 64086

The CPT codes provided are based on ViraCor’s interpretation of the American Medical Association’s Current Procedural Terminology (CPT) codes and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. ViraCor assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material. PCR tests are performed pursuant to a license agreement with Roche Molecular Systems, Inc. This assay was developed and the performance characteristics were determined at ViraCor Laboratories. This test is performed in a CLIA certified laboratory. FDA approval is not required for the performance of this test.

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Pathogen Overview

ABOUT VARICELLA-ZOSTER VIRUS

Varicella-zoster virus (VZV) was isolated and characterized in 1958, although it has been recognized as the cause of both varicella (chicken pox) and herpes zoster (shingles) for over 100 years. VZV is 1 of 8 herpesviruses that has been found to affect humans; the others include HSV-1, HSV-2, CMV, EBV, HHV-6, HHV-7, and HHV-8. The herpesvirus family is divided into 3 subfamilies; HSV-1, HSV-2, and VZV comprise the Alphawvirinae subfamily. The virus contains a linear, double-stranded DNA molecule and has a lipid-containing envelope. All members of the herpesvirus family share the ability to establish a lifelong latency in their host.

VARICELLA-ZOSTER VIRUS CLINICAL MANIFESTATIONS

Varicella and zoster are both caused by VZV, but are actually 2 distinct clinical conditions. More than 90% of the population develops a clinical or serological varicella infection by adolescence, and virtually 100% of the population by age 60. Asymptomatic infections of VZV are not uncommon; therefore, individuals reporting a negative history for varicella should have their VZV serostatus evaluated. VZV infections are medically significant, causing approximately 4 million cases of varicella (prior to advent of the vaccine) and 500,000 cases of zoster annually.

Varicella is highly contagious, with an incubation period of approximately 14 days. The virus is typically spread by airborne transmission, droplet, or contact with vesicle fluid. The host is typically infected through viral contact with the mucosa of the upper respiratory tract or the conjunctiva. Patients become contagious 2 days prior to manifestation of the rash and remain so until all lesions are crusted.

Varicella infection in an immunocompetent child is characterized by a rash, low-grade fever, and general malaise. The skin subsequently develops maculopapules, vesicles, and scabs. These evolve throughout the course of the disease, develop scabs, and fall off within 1 to 2 weeks after onset of infection.

Immunocompromised children have many more skin eruptions, and healing time is roughly 3 times longer than for immunocompetent children. These children are at a much greater risk for developing visceral complications of the lungs, liver, and central nervous system. These complications occur in approximately 30 to 50% of cases, and may be fatal in up to 15% of cases. Immunocompetent adults who develop varicella are at risk of developing encephalitis, which can be life-threatening. Approximately 30% of adult varicella patients are hospitalized for varicella pneumonia. Myocarditis, nephritis, bleeding diatheses, and hepatitis are other noncutaneous sites of involvement.

When VZV reactivates, it is known as zoster. Ten to 20% of all individuals will develop zoster, an incidence that increases dramatically with advanced age. Unfortunately, many individuals will also develop post-herpetic neuralgia, requiring long-term medical care. Zoster typically causes diffuse, varicella-like skin lesions, most often on the chest and back and occasionally around the eye. Patients usually experience pain 48 to 72 hours before the lesions appear, in the areas that will become affected. In an immunocompetent individual, lesions form over a period of 3 to 5 days. The disease lasts approximately 10 to 15 days, however, the skin may not return to normal for up to 1 month. Post-herpetic neuralgia is common; therefore, zoster is generally treated with acyclovir, even in immunocompetent individuals. When lesions occur in the trigeminal nerve area, medical treatment should be sought immediately to avoid spread of lesions into the eye and potential loss of vision.

In immunocompromised individuals, zoster can be much more serious. It may take up to 2 weeks for lesions to form, which may not scab over for 3 to 4 weeks. Due to rare occurrences of immunocompetent individuals under 45 years of age developing reactivated VZV, patients in this age group with zoster should be evaluated for the possible presence of HIV infection. As many as 30% of males with HIV will develop zoster at least one time in the 12 month period following diagnosis; they are at particular risk for complications, such as VZV retinitis, acute renal necrosis, and chronic, progressive encephalitis. Another potential complication for HIV patients is chronic zoster, in which new lesions continue to form and existing lesions do not heal.

A live attenuated vaccine is now available. It has been shown to be about 90% effective for several years in preventing varicella symptoms with a single injection. It is somewhat less effective in immunocompromised children, but has dramatically reduced the morbidity and mortality from community-acquired varicella infection. In healthy children, the vaccine may produce a few skin papules. This occurs much more frequently in immunocompromised children who may actually develop mild varicella. The attenuated vaccine can still establish latency in the dorsal ganglia and lead to zoster in later years; however, this occurs with less frequency than following natural varicella infection.

VARICELLA-ZOSTER VIRUS LABORATORY DIAGNOSIS

A diagnosis of varicella or zoster in an immunocompetent individual is typically made based upon the patient’s history and a physical examination. The characteristic skin lesions and their location are generally sufficient for a clinical diagnosis. In certain populations, such as the immunocompromised, VZV infections can cause potentially life-threatening complications. Because the course of the infection can vary from that in an immunocompetent individual, laboratory confirmation is recommended in these patients. While the virus will grow in cell culture, it is not the diagnostic method of choice due to lack of sensitivity and extended time frame required for the virus to grow. In these patients, molecular methods or immunofluorescence staining are a better choice. Quantitative, real-time polymerase chain reaction (PCR) has been shown to be a highly sensitive, accurate, and rapid means to detect VZV from a wide variety of specimen sources. It is commonly used, not only to diagnose VZV infection, but also to establish the level of viral burden (viral load) and monitor the patient’s response to therapy.

VARICELLA-ZOSTER VIRUS TREATMENT

Acyclovir has been shown to effectively decrease lesion formation and improve healing time in both immunocompetent and immunocompromised patients, which may help to prevent life-threatening complications in the immunocompromised. High dose acyclovir can improve resolution times of lesions and reduce the risk of prolonged pain for immunocompetent patients with zoster. Oral medication options include high-dose oral acyclovir, valacyclovir, or famciclovir. Immunocompromised patients should be carefully monitored for disease progression and the possible development of resistance. Valacyclovir and famciclovir have been shown to be more convenient than acyclovir and of comparable or superior efficacy. Intravenous acyclovir has been proven to prevent progression of disease in those patients who are more likely to develop disseminated disease.

Selected References

Cohen JI, Brunell PA, Strauss SE, Krause PR. Recent advances in Varicella-zoster virus infection. Ann Intern Med. 1999;(130):922-932.

Gnann JW. Varicella-zoster virus: atypical presentations and unusual complications. J Infect Dis. 2002;186(suppl 1):S91-S98.
Liesgang TJ. Varicella-zoster viral disease. Mayo Clinic Proc. 1999;(74):983-998.

Whitley R. Varicella-zoster virus. In: Mandell GL, Bennett JE, Dolin, eds. Mandell, Douglas and Bennett’s Principles and Practice of Infectious Diseases. Vol 2. 4th ed. New York, NY: Churchill Livingstone; 1995:1345-1351.

PAO-14 -0707 PCR tests are performed pursuant to a license agreement with Roche Molecular Systems, Inc.

Abstracts & Publications

Cohen JI, Brunell PA, Strauss SE, Krause PR. Recent advances in varicella-zoster virus infection. Ann Intern Med. 1999;(130):922-932.

Varicella-zoster virus has developed a complex strategy that shows it to remain latent in the body and avoid destruction by the immune system. Although varicella and zoster have been recognized since antiquity, several new clinical syndromes-including chronic chickenpox with persistent verrucous lesions and disseminated varicella without skin lesions-have been noted in patients with AIDS. Acyclovir has been the mainstay for treating severe varicella-zoster virus infections; however, newer antiviral agents, including valacyclovir and famciclovir, have expanded therapeutic options for treating adults with herpes zoster. The recently licensed live attenuated vaccine for varicella-zoster virus is effective in preventing chickenpox, and the vaccine's ability to stimulate immunity in seropositive adults suggests a promising strategy with which to modify the course of herpes zoster.

Gnann JW. Varicella-zoster virus: atypical presentations and unusual complications. J Infect Dis. 2002;186(suppl 1):S91-S98.

Varicella-zoster virus (VZV) is the etiologic agent of varicella (primary infection) and herpes zoster (reactivation of latent infection). Although varicella is most often a relatively benign and self-limited childhood illness, the disease can be associated with a variety of serious and potentially lethal complications in both immunocompetent and immunocompromised persons. One complication of varicella that appears to be increasing in frequency is serious bacterial soft tissue infections caused by group A streptococci. Issues relating to management of varicella become especially complex when varicella involves pregnant women or susceptible neonates. Herpes zoster can be associated with a variety of neurologic complications, including a syndrome of delayed contralateral hemiparesis. Neurologic complications of herpes zoster, including chronic encephalitis, occur with increased frequency in AIDS patients. VZV retinitis is a potentially sight-threatening complication that occurs in both immunocompetent and immunocompromised persons. Current knowledge regarding pathogenesis and antiviral therapy is reviewed.

Liesgang TJ. Varicella-zoster viral disease. Mayo Clin Proc. 1999;(74):983-998.

Herpes zoster is a cause of considerable morbidity, especially among elderly patients. Substantial research on the biology of the varicella zoster virus has led to advances in our knowledge of the pathophysiology of the disease along with more successful therapy for the acute episodes of herpes zoster. Ophthalmic zoster is more common than zoster in other cranial nerves and is associated with pronounced suffering. This article reviews the epidemiology, biology, and latency of herpes zoster, discusses the pathophysiology of the disease, and describes treatment options with antivirals and corticosteroids. The pathophysiology and treatment options for postherpetic neuralgia are also addressed. The varicella vaccine is now available, and initial results suggest that this may lessen the effect of herpes zoster in the future.

Whitley R. Varicella-zoster virus. In Mandell GL, Bennett JE, Dolin, eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. Vol 2. 4th ed. New York, NY: Churchill Livingstone; 1995:1345-1351.

This chapter appears in the 2nd volume of the definite textbook on infectious diseases. Chapter 116 of the text describes the history, pathogen and replication, epidemiology, pathogenesis, clinical manifestations, diagnosis, therapy and prevention of varicella-zoster virus.