PATIENT EDUCATION
Patients must be instructed in how to avoid transmitting the HZ virus. The mechanism of transmission was long thought to be restricted to direct contact with lesions; however, molecular studies have shown that the HZ virus can be transmitted via the respiratory route, either through aerosolized virus from skin lesions or from respiratory droplets, as early as 24 to 48 hours before the rash appears.6,17 The risk of transmission by airborne virus is increased in patients with HZ rash that is disseminated beyond the primary and secondary dermatomes. The rash, patients should be informed, generally persists for two to four weeks.1,16,20
HZ continues to be contagious until the lesions crust over.17 Covering the rash greatly reduces patients’ risk for transmitting the virus via airborne or direct contact routes.15,17 A patient with HZ rash can infect a nonimmune person with primary varicella, causing chickenpox.28 The patient with HZ should be advised to avoid exposure to infants younger than 1 year, unvaccinated older children, anyone who is not immune to varicella (either by vaccination or primary infection), susceptible pregnant women, and potentially susceptible immunocompromised persons.16
COMPLICATIONS AND SEQUELAE
The majority of cases of shingles resolve without any complications or long-term sequelae. Complications of HZ that do occur may include superimposed skin infections, such as Streptococcus or Staphylococcus. The virus may be reactivated in the nasociliary branch of the trigeminal nerve and, in 10% to 25% of cases, herpes zoster ophthalmicus (HZO) may develop.17,35 Associated morbidity includes keratitis, corneal ulceration, conjunctivitis, uveitis, episcleritis and scleritis, retinitis, choroiditis, optic neuritis, lid retraction, ptosis, and glaucoma. Patients with HZO should be referred to an ophthalmologist promptly, as this condition can result in permanent loss of vision.35
Other less common complications of HZ include Ramsay Hunt syndrome (facial nerve palsy associated with reactivation in the geniculate ganglion) and zoster paresis (motor weakness in noncranial nerve distributions).17,36,37 Autonomic dysfunction has also been reported in patients with HZ, leading to colonic pseudo-obstruction and urinary retention. Rare but serious neurologic complications include Guillain-Barré syndrome, myelitis, aseptic meningitis, and meningoencephalitis.15,17
Postherpetic Neuralgia
By far, the most common complication of shingles is postherpetic neuralgia, a painfully debilitating and difficult-to-treat condition. Of the one million persons affected by HZ each year, between 9% and 34% will develop PHN.3,7,18 The criteria for diagnosing PHN is variable: While all definitions include the presence of persistent pain after rash resolution, they differ in how long this pain must persist. Some define PHN as pain persisting from 30 days to six months after rash resolution, while others define it as pain continuing three months or longer.3,17,18 While most patients with PHN experience complete resolution, the pain can endure from weeks to months to years.3,18,38
The pathophysiology of PHN is thought to involve replication of the VZV in the basal ganglia, damaging the nerves and thereby causing pain in the affected dermatome.22 Other possible factors include axonal and cell body degeneration, atrophy of the dorsal horn of the spinal cord, scarring of the dorsal root ganglion, and loss of epidermal innervations of the dermatome.17
The risk for PHN increases significantly in patients of advancing age. While PHN is rare in those younger than 50, it complicates HZ in 20% of patients between ages 60 and 65 and in 30% of those 80 and older. Additional risk factors for PHN include female gender, prodromal pain preceding the HZ rash, rash that is moderate to severe, moderate to severe acute pain associated with the rash, and ophthalmic involvement.39
Evidence conflicts regarding the impact of antivirals in patients with HZ on the subsequent development of PHN. Researchers performing a meta-analysis of five randomized clinical trials found no significant difference in the incidence of PHN among patients treated for HZ with oral acyclovir, famciclovir, or placebo.34 In an older, placebo-controlled randomized clinical trial, however, famciclovir-treated patients experienced PHN of reduced duration, compared with controls (63 days vs 119 days, respectively). Six months after development of the HZ rash, 15% of treated patients continued to experience PHN symptoms, compared with 23% of controls.23 More evidence is needed.
Additional Concerns
Recurrence of HZ is uncommon in immunocompetent persons. Despite its ordinarily benign course, 1% to 4% of people with shingles require hospitalization each year, mostly elderly patients.1 In a recent study, it was estimated that 96 US deaths are attributable to HZ each year.40 Almost all HZ-associated deaths occur in elderly patients with compromised or suppressed immune systems.1
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