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Shingles and chickenpox (Varicella-zoster virus) - Diagnosis

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of shingles and chickenpox.

Alternative Names

Chicken pox; Herpes zoster; Postherpatic neuralgia

Diagnosis:

Both chickenpox (varicella) and shingles (zoster) can usually be diagnosed by symptoms alone. If a diagnosis is still unclear after a physical examination, diagnostic tests may be required.

Ruling out Other Disorders

Either variation of the virus may be confused with other disorders.

Ruling out Disorders that Resemble Chickenpox. Chickenpox, particularly in early stages, may be confused with herpes simplex (the disorder more commonly referred to as "herpes"), or impetigo, insect bites, and scabies.

Ruling out Disorders that Resemble Shingles. The early prodrome stage of shingles can cause severe pain on one side of the lower back, chest, or abdomen before the rash appears. It therefore may be mistaken for disorders, such as gallstones, that cause acute pain in internal organs.

In the active rash stage, shingles may be confused with herpes simplex, particularly in young adults, if the blisters occur on the buttocks or around the mouth. Herpes simplex, however, does not usually generate chronic pain.

A diagnosis may be difficult if herpes zoster takes a non-typical course in the face, such as with Bell's palsy or Ramsay Hunt syndrome, or if it affects the eye or causes fever and delirium.

Test to Identify the Virus

In most cases of chickenpox and shingles, the symptoms alone are enough for a health care provider to make a diagnosis. If the symptoms are not straightforward in some patients, such as those who are immunosuppressed, the doctor performs one or more additional tests to detect the virus itself. The tests usually aim to distinguish between varicella-zoster and herpes simplex viruses.

Virus Culture. A viral culture uses specimens taken from the blister, fluid in the blister, or sometimes spinal fluid. They are sent to a laboratory, where it takes 1 - 14 days to detect the virus in the preparation made from the specimen. It is also sometimes used in vaccinated patients to determine if a varicella-like infection is caused by a natural virus or by the vaccine. This test is useful, but it is sometimes difficult to recover the virus from the samples.

Immunofluorescence Assay. Immunofluorescence is a diagnostic technique used to identify antibodies to a specific virus. In the case of herpes zoster, the technique uses ultraviolet rays applied to a preparation composed of cells taken from the zoster blisters. The specific characteristics of the light as seen through a microscope will identify the presence of the antibodies. This test is less expensive than a culture, more accurate, and results are faster.

Polymerase Chain Reaction (PCR). Polymerase chain reaction (PCR) techniques use a piece of the DNA of the virus, which is then replicated millions of times until the virus is detectable. This technique is expensive but is useful for unusual cases, such as identifying infection in the central nervous system.

Resources

www.cdc.gov -- Centers for Disease Control and Prevention
www.niaid.nih.gov -- National Institute of Allergy and Infectious Diseases
www.ninds.nih.gov -- National Institute of Neurological Disorders and Stroke
www.aan.com -- American Academy of Neurology
www.neuropathy.org -- Neuropathy Association

References

Advisory Committee on Immunization Practices. Recommended adult immunization schedule: United States, 2009. Ann Intern Med. 2009 Jan 6;150(1):40-4.

American Academy of Pediatrics Committee on Infectious Diseases. Prevention of varicella: recommendations for use of varicella vaccines in children, including a recommendation for a routine 2-dose varicella immunization schedule. Pediatrics. 2007 Jul;120(1):221-31.

American Academy of Pediatrics Committee on Infectious Diseases. Recommended immunization schedules for children and adolescents -- United States, 2007. Pediatrics. 2007 Jan;119(1):207-8.

Centers for Disease Control and Prevention (CDC). A new product (VariZIG) for postexposure prophylaxis of varicella available under an investigational new drug application expanded access protocol. MMWR Morb Mortal Wkly Rep. 2006 Mar 3;55(8):209-10.

Centers for Disease Control and Prevention (CDC); Advisory Committee on Immunization Practices (ACIP). Update: recommendations from the Advisory Committee on Immunization Practices (ACIP) regarding administration of combination MMRV vaccine. MMWR Morb Mortal Wkly Rep. 2008 Mar 14;57(10):258-60.

Chaves SS, Gargiullo P, Zhang JX, Civen R, Guris D, Mascola L, et al. Loss of vaccine-induced immunity to varicella over time. N Engl J Med. 2007 Mar 15;356(11):1121-9.

Davis MM, Marin M, Cowan AE, Guris D, Clark SJ. Physician attitudes regarding breakthrough varicella disease and a potential second dose of varicella vaccine. Pediatrics. 2007 Feb;119(2):258-64.

Harpaz R, Ortega-Sanchez IR, Seward JF; Advisory Committee on Immunization Practices (ACIP) Centers for Disease Control and Prevention (CDC). Prevention of herpes zoster: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2008 Jun 6;57(RR-5):1-30.

Kimberlin DW, and Whitley RJ. Varicella-zoster vaccine for the prevention of herpes zoster. N Engl J Med. 2007 Mar 29;356(13):1338-43.

Marin M, Güris D, Chaves SS, Schmid S, Seward JF; Advisory Committee on Immunization Practices, Centers for Disease Control and Prevention (CDC). Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2007 Jun 22;56(RR-4):1-40.

Marin M, Meissner HC, Seward JF. Varicella prevention in the United States: a review of successes and challenges. Pediatrics. 2008 Sep;122(3):e744-51.

Myers MG, Seward JF, LaRussa PS. Varicella-zoster virus. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Kliegman: Nelson Textbook of Pediatrics. 18th ed. Saunders; 2007:chap 250.

Quan D, Hammack BN, Kittelson J, Gilden DH. Improvement of postherpetic neuralgia after treatment with intravenous acyclovir followed by oral valacyclovir. Arch Neurol. 2006 Jul;63(7):940-2.

Sampathkumar P, Drage LA, Martin DP. Herpes zoster (shingles) and postherpetic neuralgia. Mayo Clin Proc. 2009 Mar;84(3):274-80.

Strangfeld A, Listing J, Herzer P, Liebhaber A, Rockwitz K, Richter C, et al. Risk of herpes zoster in patients with rheumatoid arthritis treated with anti-TNF-alpha agents. JAMA. 2009 Feb 18;301(7):737-44.

Tyring SK. Management of herpes zoster and postherpetic neuralgia. J Am Acad Dermatol. 2007 Dec;57(6 Suppl):S136-42.

Urman CO and Gottlieb AB. New viral vaccines for dermatologic disease. J Am Acad Dermatol. 2008 Mar;58(3):361-70.

Whitley RJ, Gnann JW Jr. Herpes zoster in the age of focused immunosuppressive therapy. JAMA. 2009 Feb 18;301(7):774-5.

Woolery WA. Herpes zoster virus vaccine. Geriatrics. 2008 Oct;63(10):6-9.

Reviewed last on: 5/21/2009
Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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