Zoster

Herpes zoster is a viral disease caused by reactivation of latent varicella-zoster virus (human herpesvirus 3) residing in dorsal root or cranial nerve ganglia following prior primary varicella infection. The resulting syndrome is characterized by virus replication along sensory nerves, leading to inflammation, neuronal injury, and a painful unilateral dermatomal rash ^{[1][2][3][4][5]}.

HZ classically begins with a prodrome of malaise, headache, low-grade fever, and abnormal skin sensations such as tingling or localized pain lasting two to four days, followed by a unilateral maculopapular rash confined to a single dermatome that progresses to clear vesicles, clouding, and crusting over seven to ten days ^[2][4]. Dermatomal involvement of the trigeminal nerve, particularly the ophthalmic division, produces herpes zoster ophthalmicus in approximately 10–25% of cases and can lead to conjunctivitis, keratitis, uveitis, optic nerve palsies, and vision loss ^[2]. Other manifestations include zoster oticus (Ramsay Hunt syndrome) with facial paralysis and ear involvement, widespread cutaneous dissemination in the immunocompromised, and zoster sine herpete with dermatomal pain but no rash ^[2][3].

Because HZ is secondary to prior varicella, its incidence rises steeply with age and is uncommon in children, where it is often associated with underlying metabolic or neoplastic disorders ^[1]. In the United States, an estimated 1 million cases occur annually, translating to an individual lifetime risk of approximately 30% ^[4]. Patients with conditions impairing cell-mediated immunity carry a 20- to 100-fold higher risk of developing HZ compared with immunocompetent individuals ^[4].

HZ results from endogenous reactivation of latent VZV within sensory ganglia rather than from person-to-person spread of zoster itself, although direct contact with vesicular fluid from active shingles lesions can transmit VZV to varicella-naïve individuals, causing primary varicella rather than zoster ^[2].

Two zoster vaccines are currently available for healthy older adults: a live attenuated VZV vaccine and a recombinant adjuvanted VZV glycoprotein E subunit vaccine, with the latter being suitable even for severely immunosuppressed patients ^[1]. The recombinant zoster vaccine has demonstrated an overall vaccine efficacy of approximately 97.2% in clinical evaluation, and the live varicella zoster virus vaccine reduces HZ incidence and is approved for adults aged 50 years and older, with the CDC's Advisory Committee on Immunization Practices recommending it for adults 60 years and older (with certain immunosuppression exceptions) ^[3][4].

1. 1Patil A et al. Herpes zoster: A Review of Clinical Manifestations and Management. Viruses. 2022 Jan 19. PMID: 35215786. doi: 10.3390/v14020192.PubMed: https://pubmed.ncbi.nlm.nih.gov/35215786/
2. 2Wikipedia contributors. Shingles - Wikipedia [Internet]. Wikipedia. cited 3 Sept 2026.Available from: https://en.wikipedia.org/wiki/Shingles
3. 3Lim DZJ et al. Herpes Zoster and Post-Herpetic Neuralgia-Diagnosis, Treatment, and Vaccination Strategies. Pathogens. 2024 Jul 17. PMID: 39057822. doi: 10.3390/pathogens13070596.PubMed: https://pubmed.ncbi.nlm.nih.gov/39057822/
4. 4Saguil A et al. Herpes Zoster and Postherpetic Neuralgia: Prevention and Management. Am Fam Physician. 2017 Nov 15. PMID: 29431387.PubMed: https://pubmed.ncbi.nlm.nih.gov/29431387/
5. 5Gershon AA et al. Varicella zoster virus infection. Nat Rev Dis Primers. 2015 Jul 2. PMID: 27188665. doi: 10.1038/nrdp.2015.16.PubMed: https://pubmed.ncbi.nlm.nih.gov/27188665/