Chicken Pox

Last updated 20.09.12

Definition

-  Primary infection with Varicella Zoster Virus

 

Features

-  > 90% cases < 10 years old

-  Benign condition in healthy children

-  Increased morbidity in adults & immunocompromised

-  Spread by airborne respiratory droplets or direct contact w vesicles

-  Highly contagious, causes epidemics

-  IgG antibodies persist for life & confer immunity

 

Associated S/S

-  Prodrome

-  Typically not in paediatric population

-  Common in adolescents & adults: nausea, myalgia, anorexia, headache

-  Rash

-  Exanthem heralds onset

-  Mucules --> papules --> vesicles --> pustules --> crusts

-  Small vesicles on erythematous base: Dew drops on a rose petal

-  Infectious 1-2 days prior to rash to 4-5 days after

-  Crusted lesions are not infectious

-  Lesions are of various stages & therefore appear different, suggest ongoing process

-  Lesions are present within hair line

-  Mucus membrane vesicles may cause oropharyngeal or urogenital ulcers

-  DDx: contact allergy

 

Rash

 

-  Secondary bacterial infection

-  Strep, Staph

-  Impetigo, cellulitis, erysipelas --> septicaemia --> pneumonia, otitis media, necrotizing fasciitis

-  After infection lies dormant in spinal root ganglion & may reactivate as Herpes Zoster (Shingles)

 

Dx

-  Clinical Dx based on rash

-  Onset typically rash, malaise & low grade fever

 

Ix

-  Tzanck smear or vesicular fluid

-  Giant cells

-  Epithelial cells w eosinophillic intranuclear inclusions

-  Latex agglutination test: Varicella antibodies

 

Mx

-  Notifiable disease in Australia

-  Healthy child: symptomatic Mx

-  Prutitus: calamine lotion, pramoxine geloatmeal baths, oral antiistamines

-  Adults: oral Acyclovir within 24hrs of S/S

-  VZV in Pregnancy

-  Immunocompromised

-  IV Acyclovir

-  Acyclovir resistant strains have been reported in pts w AIDS

-  Varicella Zoster Immunoglobulin (VZIG) used for highly susceptible pts withint 96 hrs of exposure

-  Chicken Pox Vaccine

-  Immunisation

-  Live attenuated Varicella Zoster (Oka strain)

-  1st dose at 12-18 months +

-  2nd & 3rd doses 4-8 weeks after

-  Pre-pregnany if non-immune

-   Avoid pregnancy for 3 months after 2nd dose

-  Breakthrough Varicella possible: milder, atypical

-  ? not life long, not 100% effective

 

 

 

 

 

References