What is the herpes zoster virus?

Related condition:
Shingles

Definition:

Herpes zoster is an infection caused by the same virus that causes chickenpox, the varicella-zoster virus (VZV). This virus remains in the nerve cells for life in people who had chickenpox or received the chickenpox vaccine. The virus reappears as herpes zoster (shingles) later in life particularly in the elderly and immunocompromised persons. The virus is reactivated because the body loses its immunity to the varicella-zoster virus over time.

Risk factors: People with certain types of cancers are at an increased risk of developing herpes zoster because of their altered immunity. People who had chickenpox or the chickenpox live-virus vaccine are at risk for developing herpes zoster. The risk increases as people get older: the Centers for Disease Control and Prevention (CDC) reports that, as of 2014, about 50 percent of all people with herpes zoster are older than age sixty.

Etiology and the disease process: Herpes zoster results when the latent VZV within the sensory ganglia is reactivated.

The first signs of the disease are pain and a burning sensation on one side of the body. These symptoms may last up to five days. Then the skin reddens and blisters form on the skin on the affected side of the body. Within seven to ten days, the blisters will ooze and crust, and begin to heal. The whole disease process takes up to five weeks.

The reactivation of VZV is higher in cancer patients because cell-mediated immunity in these patients is deficient as a result of chemotherapy or the disease itself. Also, a Russian case study found that the whole disease process is generally longer in cancer patients. Nevertheless, a 2014 study published in Clinical Infectious Diseases found that older cancer patients who had been vaccinated against herpes zoster prior to undergoing chemotherapy were more than 40 percent less likely to develop it than those who had not been vaccinated.

Because the infection affects the nerves, herpes zoster can be painful. A common complication that occurs in one-third of older patients is postherpetic neuralgia (PHN), as noted by the CDC. In postherpetic neuralgia patients, the rash and the pain are severe and last for months.

Incidence: According to the CDC, each year, about a million cases of herpes zoster are reported in the United States. The annual incidence of herpes zoster is about four per thousand persons for the general population and ten per thousand for those over age sixty.

Symptoms: The appearance of herpes zoster is accompanied by pain in one side of the body along with tingling and a burning sensation. The skin reddens and blisters appear. The small blisters are dense and deep and may ooze and crust. Other symptoms include headache, fever, chills, abdominal pain, joint pain, lymph node swelling, hearing loss, genital lesions, vision and taste problems, and a general feeling of malaise.

Screening and diagnosis: The skin blisters and a prior history of varicella or shingles are the basis for diagnosis. Tests are rarely used; however, tests such as a viral culture of a blister can be used to identify the herpes zoster virus. Other tests include the following:

• Tzanck test: The sore on the skin is scarred, and the sample is stained for examination under a microscope.





• 
  Complete blood count (CBC): The blood is tested to look for nonspecific signs of infection such as an elevated number of white blood cells.





• Immunoglobulin measurement: Blood is tested to measure the level of varicella antibodies.

Treatment and therapy: Although the disease disappears on its own after a few weeks, treatment is usually necessary for pain. The antiviral medication acyclovir reduces pain and complications and protects immunocompromised individuals such as cancer patients. Other medicines that can be used are desciclovir, famciclovir/penciclovir, and valacyclovir.

According to the US National Library of Medicine, treatment with these drugs should begin within seventy-two hours of the initial signs and, if possible, before blistering. Although these drugs are generally given as pills, some cancer patients may require intravenous acyclovir therapy if they are severely immunocompromised. Other suggestions for treatment are as follows:

• Control the pain with analgesics and the itching with antihistamines.





• Use a capsaicin-containing cream to prevent postherpetic neuralgia.





• Keep the affected skin covered and dry.





• Keep skin clean and do not reuse contaminated items.





• Rest in bed and avoid contact with others.

Prognosis, prevention, and outcomes: Usually herpes zoster lesions heal within two to three weeks after the first signs appear. Patients, especially the elderly, may experience a temporary or permanent weakness or paralysis or may develop a continued nerve pain that persists for years. If the eyes are affected, the person may become blind if not treated.

In 2006, a live zoster vaccine was licensed and recommended for routine administration to adults over the age of sixty. However, the vaccine is not recommended for people taking immunosuppressive therapy, including high-dose corticosteroids, or for people with primary or acquired immunodeficiency states including leukemia, lymphoma of any type, other malignant neoplasms affecting the bone marrow or lymphatic system or acquired immunodeficiency (AIDS) or other clinical manifestations of infection with human immunodeficiency viruses.

Bibliography

American Academy of Pediatrics. “Varicella-Zoster Infections.” Red Book: 2006 Report of the Committee on Infectious Diseases. Ed. L. K. Pickering, C. J. Baker, D. W. Kimberlin, and S. S. Long. 29th ed. Elk Grove Village: AAP, 2012. Web. 13 Oct. 2014.

Bogomolov, B. P., and E. G. Bakhur. “Herpes Zoster in Cancer Patients.” Ter Arkh 62.1 (1990): 99–103. Print.

Carson-DeWitt, Carolyn, and David Horn. "Conditions InDepth: Shingles." Health Library. EBSCO, May 2014. Web. 15 Oct. 2014.

Gnann, John W., Jr., and Richard J. Whitley. “Herpes Zoster.” New England Journal of Medicine 347.5 (2002): 340–46. Print.

"Infections in People with Cancer." Cancer.org. Amer. Cancer Soc., 6 Nov. 2013. Web. 15 Oct. 2014.

National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. "Shingles (Herpes Zoster)." CDC.gov. Centers for Disease Control and Prevention, 1 May 2014. Web. 15 Oct. 2014.

Oxman, M. N., et al. “A Vaccine to Prevent Herpes Zoster and Postherpetic Neuralgia in Older Adults.” New England Journal of Medicine 352.22 (2005): 2271–84. Print.

Preidt, Robert. "Shingles Vaccine Still Effective after Chemotherapy." HealthDay. MedlinePlus, US Natl. Lib. of Medicine, 8 Aug. 2014. Web. 15 Oct. 2014.

"Shingles." MedlinePlus. US Natl. Lib. of Medicine, 6 June 2013. Web. 15 Oct. 2014.

Siegel, Mary-Ellen, and Gray Williams. Shingles: New Hope for an Old Disease. Rev. ed. Lanham: Evans, 2008. Print.