Varicella-Zoster-Virus (HHV3, VZV, Herpes Zoster)

Figure 4.3 A: Disseminated varicella (Courtesy of Dr. Sophie M. Worobec) B: Herpes zoster, trunk C: Herpes zoster, magnified

(Figure 4.3B, C)

• Initial infection causes varicella (Figure 4.3A) and following resolution, virus lies dormant in spinal dorsal root ganglion until reactivation as herpes zoster
• Of note, women with varicella infection 5 days before or 2 days after delivery can result in severe acute infection of newborn (neonatal varicella, mortality of newborn up to 30%); different from VZV embryopathy or congenital varicella syndrome which occurs in first 20 weeks of pregnancy
• Zoster: 75% cases with precedent prodromal pain/paresthesias, followed by grouped, painful erythematous macules/papules along single sensory dermatome (rarely crossing midline) → vesicles/bullae → rupture forming hemorrhagic crust and become dry over 7–10 days; lesions are infectious until dry
• Atypical presentation in AIDS pts: >2 dermatomes affected, may cross midline, may present with verrucous or crusted lesions
• Complications: postherpetic neuralgia (PHN), scarring, secondary bacterial infection, meningoencephalitis, Ramsay–Hunt syndrome, ocular blindness, motor paralysis
• Ocular involvement: lesions on tip of nose signal possible ocular infection (since nasociliary nerve involved, which is a branch of the ophthalmic nerve)
• Ramsay–Hunt syndrome: infection of geniculate ganglion → ear canal/ auricle/tympanic membrane involvement with painful vesicles, facial paralysis/paresis, ipsilateral hearing loss
• Visceral involvement (hepatitis, pneumonitis, encephalitis, etc) may occur with disseminated zoster in immunocompromised patients
• Treatment: antiviral best if within 48–72 h within appearance of rash (can ↓ PHN risk); of note, concomitant corticosteroid use has no effect on development/duration of PHN; IV acyclovir used in immunocompromised patient if advanced HIV, widespread skin involvement, visceral disease or transplant patients