Vaccines and Preventable Diseases:

Herpes Zoster Disease - Q&As for Providers
(Shingles)

Questions about Shingles (From Chickenpox Virus)

What is shingles?

Shingles, also known as herpes zoster, or zoster, is caused by infection with the varicella zoster virus (VZV), the same virus that causes chickenpox. Primary infection with VZV causes chickenpox. Once the chickenpox illness resolves, the virus remains in the dorsal root ganglia. Reactivation of the virus results in a localized cutaneous rash called shingles.

How does shingles typically present?

Shingles typically presents as a painful rash in a single dermatome, most commonly the thoracic dermatomes. Pain, itching, or tingling in the area where the rash develops is typical. This may precede rash onset by one to five days. Headache, photophobia, and malaise may also occur in the prodromal phase. The rash is usually localized to a single dermatome and does not cross the body’s midline. It begins as an erythematous, maculopapular rash that develops into clusters of clear vesicles. New vesicles continue to form over 3-5 days which then crust, and healing occurs over 2-4 weeks. There may be residual scarring and changes in pigmentation, and lesions may overlap adjacent dermatomes in 20% of cases. In rare cases, usually among immunocompromised persons, the rash may become generalized and appear similar to the rash of varicella (chickenpox) infection.

What are the complications of shingles?

The most common complication of shingles is postherpetic neuralgia (see below). Other complications include ophthalmic involvement with acute or chronic ocular sequelae; bacterial superinfection of the lesions, usually due to Staphylococcus aureus and, less commonly, to group A beta hemolytic streptococcus; cranial and peripheral nerve palsies; and visceral involvement (e.g., meningoencephalitis, pneumonitis, hepatitis, acute retinal necrosis). Due to the use of antiviral therapy, disseminated shingles occurs rarely in immunocompetent persons. Complications occur more frequently and with increased severity in persons with immunosuppressive medical conditions or those taking immunosuppressive medications.

What is postherpetic neuralgia?

After the shingles rash resolves, pain may persist in the area where the rash was present. This is known as postherpetic neuralgia (PHN), and it occurs in 8% to 70% of shingles cases . The duration of pain used to define PHN has been inconsistent, ranging from any duration after resolution of the rash to periods from >30 days to >6 months after rash onset. The pain of PHN can last for weeks or months but occasionally persists for many years. The frequency, duration, and severity of PHN increases with increasing age: It occurs rarely among persons under 40 years of age but occurs in up to 50% (and possibly more) of persons 60 years of age and older. The pain may be severe and debilitating, and it resolves over time in many patients.

What immunologic factors are important in the development of shingles?

It is thought that declining VZV-specific cell-mediated immunity is important in the development of shingles. This declining immunity is related to age and/or immunosuppressive medical conditions and medications.

Who is at risk for developing shingles?

Anyone who has had chickenpox may develop shingles, including children. However, shingles most commonly occurs in older people, with the risk increasing sharply after 50 years of age. It is also more common in people who are immunocompromised or who are taking medications that suppress the immune system—specifically, cell-mediated immunity; they include people:

• With cancer, especially leukemia and lymphoma;
• With human immunodeficiency virus;
• Who have undergone bone marrow transplantation; or
• Who are taking immunosuppressive medications, including steroids, chemotherapy, or transplant-related immunosuppressive medications.

How often can a person get shingles?

Most people typically have only one episode of shingles in their lifetime; however, second and even third episodes are possible. The annual incidence of repeated episodes of shingles is not known.

Can someone who has been vaccinated against chickenpox get shingles?

Currently available data suggest that children who have been vaccinated against chickenpox may develop shingles later in life, but they do so at lower rates than those who have been infected with wild type varicella. In a study among children with leukemia, the risk of shingles occurring in vaccine recipients was about one-third that of children who had had chickenpox. Data relating to the risk of shingles in healthy children show a similar pattern of reduced risk in vaccine recipients, but these data are limited, and they do not distinguish between shingles resulting from the varicella vaccine virus and shingles resulting from natural VZV infection as a result of varicella vaccine failure. Furthermore, since the number of older adults who have received varicella vaccine since it was licensed in 1995 is quite low, these data are only available for children, and children are generally at low risk for shingles.

How common is shingles in the United States?

On the basis of data from the National Health and Nutrition Examination Survey (NHANES 1988-1994), it is estimated that 98% of adults 20 years old or older in the United States have serologic evidence of VZV infection and are at risk for shingles. The lifetime risk of developing shingles is estimated to be about 30%. In the United States, there are an estimated one million cases of shingles annually.

Is shingles contagious?

The virus that causes shingles can be transmitted from a person with active shingles to a person who is susceptible to infection with VZV (i.e., has not had chickenpox or has not had the chickenpox vaccine). The recipient (susceptible person) would develop chickenpox, not shingles. A person is contagious when the rash is in the blister phase; once the rash has developed crusts, the person is no longer contagious. A person in the prodromal phase or who has PHN is not contagious.

How is the virus transmitted from a person with shingles?

The virus is transmitted by direct contact with a person with shingles, especially direct contact with the rash. The risk of transmission is low if the lesions are covered. Lesions are infectious until they are dry and crusted.

What can be done to prevent transmission of VZV from patients with shingles in healthcare settings?

Infection control measures depend on whether the patient with shingles is immunocompetent or immunocompromised, and whether the rash is localized or disseminated. In all cases, standard infection control precautions should be followed.

• If the patient is immunocompetent with a:  
  • localized rash, Standard Precautions should be followed.
  • disseminated rash, Standard Precautions plus Airborne and Contact Precautions should be followed.

• If the patient is immunocompromised with a:
• localized rash, Standard precautions plus Airborne and Contact Precautions should be followed, until disseminated infection is ruled out. Then Standard Precautions should be followed.
  
• disseminated rash, Standard Precautions plus Airborne and Contact Precautions should be followed.

REFERENCES

Gnann JW and Whitely RJ. Herpes Zoster. New Engl J Med 2002;347:340-6.

Oxman MN , et al. A Vaccine to Prevent Herpes Zoster and Postherpetic Neuralgia in Older Adults. New Engl J Med 2005.352:2271-.

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