Organism
Varicella-zoster virus (hepesvirus) – only 1 recognized strain, humans are the only source of infection
Transmission
- Person-to-person by direct contact with varicella/zoster and respiratory secretions (droplets)
- Most cases between 5-9 years old
- Risk of more severe disease in extremes of age and immunocompromised
Incubation
- 10 – 21 days after contact
- Most contagious 2 days before rash develops until all lesions crusted over (longer in immunocompromised)
- Prodrome: 1-2 days before rash with malaise and mild fever
Differential diagnosis
Vesicular rash
- Coxsackie virus (hand, foot and mouth disease)
- Rickettsial pox
- Molluocerm contagorm
- Eczema herpeticum
- Herpes zoster with dissemination
Rash
Successive crops of macules, papules and vesicules – crops appear every 3 days
“A dew drop on a rose petal”
3 phases:
- Maculopapular, progressing from head to toe
- Vesicular
- Crusting and healing (non-infectious)
Tests
Serology – only to determine presence of immunity
PCR – rapid diagnostic test for use in high risk individuals
Complications (esp in neonates and immunocompromised)
- Secondary bacterial infection
- Pneumonia
- Encephalitis
- Meningitis
- Necrotizing enterocolitis
Treatment
- Neonates: if mother has a rash 5 days antepartum or 2 days postpartum
- Immunocompromised
- <72hr VZIG
- >72hr IV Acyclovir
- Healthy children – Tylenol, cool baths, Calamine lotion and Benadryl for itch
Prevention
Varivax: live attenuated virus (97% seroconversion rate)
- Healthy children at 1 years old
- <13 yo without immunity – 1 dose
- ≥13 yo without immunity – 2 doses 1-2months apart
- Contraindicated in pregnancy and immunosuppressed
History
- Characterize rash (onset, position, progression, appearance, change over time, pruritis)
- Prodromal symptoms (fever, malaise, HEENT, resp, abdo, GU, MSK)
- Exposure to anyone with rash… when?
- Complications?
- Past medical history, Social, family history, Immunizations, medications, Allergy/Atopy