An Overview of Herpes zoster: Aetiology, Pathogenesis and Treatment

Varicella zoster virus is one of the eight herpes viruses that are pathogenic only for humans. It is alpha-herpes zoster of the genus varicellovirus, which causes varicella (chickenpox) and zoster (shingles). Herpes zoster is described as a multivesicular eruptive rash that follows a single or multiple adjacent dermatomal distribution. VZV infection begins with replication in epithelial cells of upper respiratory mucosa, which is followed by widely distributed vesicular rash. Cell-mediated immunity plays a role in this reactivation. Patients with conditions that decrease cell-mediated immunity are 20 to 100 times more prone to develop herpes zoster. It is often accompanied by acute pain and itchiness. Complications may be dermatological (e.g. secondary bacterial infection), neurological (e.g. long-term pain, segmental paresis, stroke), ophthalmological (e.g. keratitis, iridocyclitis, secondary glaucoma) or visceral (e.g. pneumonia, hepatitis). Most common Complications of the infection are post herpetic neuralgia and ophthalmic zoster. Treatment includes antiviral medications such as acyclovir, famciclovir, and valacyclovir given within 72 hours of symptom has been shown to reduce severity and complications associated with herpes zoster and post-herpetic neuralgia, both these diseases are vaccine preventable. Before the invention of the recombinant VZV vaccine, live VZV vaccine was the recommended immunization, approved for adults 50 years and older.