Transmission of herpes zoster
The lesions of persons with herpes zoster contain a high concentration of VZV, which can spread to and cause varicella in susceptible persons who have not had the primary infection (varicella). Herpes zoster is contagious after the rash erupts and until the lesions crust. However, herpes zoster is not as contagious as varicella. Transmission can be decreased by covering the lesions. Herpes zoster is not a reportable condition and is not associated with epidemic spread.7,10
Persons with herpes zoster should avoid contact with susceptible persons in their household or occupational setting until the lesions crust. Susceptible persons include those who have not had chickenpox or received varicella vaccine, pregnant women, premature infants, and immunocompromised individuals.7,10
In recipients of the varicella vaccine, the vaccine strain of VZV can become dormant and clinically reactivate as herpes zoster. The risk for the development of herpes zoster caused specifically by the vaccine strain of VZV is unknown. Clinically, the herpes zoster rash caused by the vaccine strain of VZV is indistinguishable from that caused by natural infection. The inception of the varicella vaccine was in 1995, and with time, additional research will be conducted on the development of herpes zoster in children vaccinated for varicella.10,13
Diagnosis of herpes zoster
Herpes zoster is most commonly diagnosed on the basis of the identification of its clinical manifestations as a vesicular, linear rash in a dermatomal pattern in a patient with a known history of past chickenpox.8
Schmader13 considers polymerase chain reaction (PCR) assay to be the best diagnostic test because it can detect VZV DNA in fluid obtained from vesicular lesions or cell scrapings. Diagnostic testing may be needed to differentiate herpes simplex from herpes zoster in some immunosuppressed patients.
For patients with zoster sine herpete, in which symptoms of pain occur but no rash, PCR assay of blood can be used. Visceral herpes zoster can present without a rash, and the diagnosis can be challenging. For persons with central nervous system involvement, PCR assay of the cerebrospinal fluid can be conducted.14 Herpes zoster of the gastrointestinal tract can be diagnosed with a PCR assay of saliva.15
Treatment of acute herpes zoster
The nucleoside analogues acyclovir, famciclovir, and valacyclovir can inhibit viral replication in persons with herpes zoster. These agents decrease the duration of viral shedding, reduce lesion formation, hasten healing, and decrease the risk for progression to postherpetic neuralgia. The bioavailability of famciclovir and valacyclovir is better than that of acyclovir.8,16 The treatment regimens differ depending on the agent used (Table 2). The outcome is optimal if treatment is initiated within 72 hours of rash onset.
Pain management is most important when herpes zoster is being treated. Antiviral medications can decrease pain, but mild-to-moderate pain can be managed with acetaminophen or oral nonsteroidal anti-inflammatory drugs.17
While blistering lesions are present, lotions containing calamine or oatmeal baths may be helpful. The rash should be kept clean, dry, and covered to prevent bacterial superinfection. The patient should avoid scratching the lesions. Once the lesions have crusted, capsaicin cream is effective for relief of pain.17