PetriKey

Disease

Chickenpox and shingles

Primary varicella vs zoster reactivation

vzvherpesvirusvesiculardermatomalviral

High-yield clue

Generalized vesicles in different stages ('dew drop on a rose petal') is chickenpox; a painful unilateral dermatomal vesicular rash is shingles reactivation.

Overview

Two presentations of varicella-zoster virus: primary varicella (chickenpox) and later reactivation as zoster (shingles), studied for lesion pattern and viral latency.

Classification

  • Viral exanthem / reactivation syndrome
  • Herpesvirus (VZV)
  • Airborne plus contact spread
  • Latency in dorsal root ganglia

Lab & identification clues

  • Tzanck smear multinucleated giant cells vocabulary
  • Vesicles in different stages (varicella)
  • Single-dermatome distribution (zoster)

Associations

  • Airborne/contact spread of vesicular fluid
  • Reactivation with age or immunosuppression
  • Postherpetic neuralgia vocabulary
  • Vaccine-preventable exanthem

Commonly confused with

  • Smallpox (variola)
  • Disseminated herpes simplex
  • Hand-foot-and-mouth disease

Your notes

Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.

OpenStax: Microbiology 2e organism classification foundationssourceNCBI Bookshelf: Medical Microbiology organism chapterssourceCDC: CDC disease and public-health topic pagessource