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Varicella (Chicken Pox) Varicella (Chicken Pox)
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Varicella Varicella
Varicella Varicella (chickenpox)(chickenpox)
² ² primary infectionprimary infection
Herpes zoster ( Herpes zoster ( shinglesshingles ) ) ² ² recurrent formrecurrent form
Varicella Varicella (chickenpox)(chickenpox) ² ² primary infectionprimary infection
Herpes zoster ( Herpes zoster ( shinglesshingles ) ) ² ² recurrent formrecurrent form
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EtiologyEtiology
Varicella Varicella ² ² Zoster (DNA virus )Zoster (DNA virus )
HumansHumans ² ² only reservoironly reservoir
Only one serotype is knownOnly one serotype is known
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E pidemiologyE pidemiology
attack rate of at least 90% among susceptibleattack rate of at least 90% among susceptible
(seronegative ) individuals(seronegative ) individuals children 5children 5² ²9 years9 years -- 50% of all cases50% of all cases
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Incubation Period: 10Incubation Period: 10--2121daysdays
Mode of TransmissionMode of Transmission
by respiratory dropletsby respiratory droplets
direct contactdirect contact
linen or fomiteslinen or fomites
vertical vertical transmissiontransmissionduring pregnancy during pregnancy
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ContagiousContagious
A day before eruptions A day before eruptions
Until all vesicles are crusted (5Until all vesicles are crusted (5--66thth
day )day )
Immunity Immunity ² ² long lasting long lasting
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VZV transmission VZV transmission
inoculation of virus onto the mucosa of URT andinoculation of virus onto the mucosa of URT and
tonsillar lymphoid tissuetonsillar lymphoid tissue
Primary Viremic PhasePrimary Viremic Phase
Secondary Viremic PhaseSecondary Viremic Phase
VZV to upper res piratory VZV to upper res piratory
mucosal sitesmucosal sites
Vesicular lesions Vesicular lesions
PathophysiologyPathophysiology
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Clinical ManifestationsClinical Manifestations
In healthy children, the disease is generally mildIn healthy children, the disease is generally mild
IPIP FeverFever ² ² usually low grade preceding skin manifestationusually low grade preceding skin manifestation
malaise, anorexia, headache, cough, runny nose, decreasedmalaise, anorexia, headache, cough, runny nose, decreasedappetiteappetite
Superficial vesicular lesionsSuperficial vesicular lesions ´dewdrop on a rose petalµ´dewdrop on a rose petalµ
PruriticPruritic Trunk, face or trunk Trunk, face or trunk centrifugalcentrifugal
All developmental stages of the rash are present at the same All developmental stages of the rash are present at the sametimetime
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LaboratoryLaboratory
Viral Isolation Viral Isolation
yy Vesicular scrapings (Tzanck smear ) Vesicular scrapings (Tzanck smear ) -- multimulti--nucleatednucleatedgiant cells, consistent with VZV and herpes simplexgiant cells, consistent with VZV and herpes simplex virus ( HSV ) infection. virus ( HSV ) infection.
yy fluorescent monoclonal antibody testfluorescent monoclonal antibody test -- very sensitive very sensitiveand specificand specific
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Serologic Testing Serologic Testing ----
Antibody Tests: Antibody Tests: Complement fixation ( CF ): Commercially available, but lacksComplement fixation ( CF ): Commercially available, but lacks
sensitivity.sensitivity.
Neutralization test (NT ): Sensitive and specific; timeNeutralization test (NT ): Sensitive and specific; timeconsuming and difficult to perform; not readily available.consuming and difficult to perform; not readily available.
Immunofluorescence assay for antibody to VZV Immunofluorescence assay for antibody to VZV--inducedinducedmembrane antigen (FAMA ): sensitive, time consuming, notmembrane antigen (FAMA ): sensitive, time consuming, notreadily available.readily available.
Immune adherence hemagglutination ( I AH A ) sensitive; notImmune adherence hemagglutination ( I AH A ) sensitive; notreadily available.readily available.
EnzymeEnzyme--linked immunosorbent assay (ELISA ): Sensitive,linked immunosorbent assay (ELISA ): Sensitive,simple, and commercially available; may be useful for routinesimple, and commercially available; may be useful for routinetesting.testing.
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Treatment Treatment
Healthy childrenHealthy children
no medical treatmentno medical treatment
antihistamine to relieve itching antihistamine to relieve itching
Oral therapy with acyclovir (20 mg/kg/dose, maximum 800Oral therapy with acyclovir (20 mg/kg/dose, maximum 800
mg/dose ) given as 4 doses/day for 5 days should be used to treatmg/dose ) given as 4 doses/day for 5 days should be used to treatuncomplicated varicellauncomplicated varicella
I V AcyclovirI V Acyclovir (nucleoside analogues ) (nucleoside analogues )
< 1 yr 30 mg/kg/day in 3 divided doses for 7< 1 yr 30 mg/kg/day in 3 divided doses for 7--10 days10 days
>> 1 yr 1500 mg/m1 yr 1500 mg/m22/day divided q 8 h for 7/day divided q 8 h for 7--10 days10 days
Immunocompromised patientsImmunocompromised patients Patients being treated with chronic corticosteroidsPatients being treated with chronic corticosteroids
medications to shorten the duration of the infectionmedications to shorten the duration of the infection
help reduce the risk of complicationshelp reduce the risk of complications
Recommendations of the Advisory Committee on Immunization Practices. MMWR 200 6;55:209-210.
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Valacyclovir and Famciclovir Valacyclovir and Famciclovir
approved for use only in adultsapproved for use only in adults
Don't give Aspirin : Reye's syndrome.Don't give Aspirin : Reye's syndrome.
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Complications of VaricellaComplications of Varicella
herpes zoster (shingles )herpes zoster (shingles )
lifetime risk 15%lifetime risk 15%--20%20%
mainly affecting themainly affecting the
elderly andelderly andimmunocompromisedimmunocompromisedpersonspersons
secondary bacterial skinsecondary bacterial skin
and soft tissue infectionsand soft tissue infections otitis mediaotitis media
bacteremia,bacteremia, pneumonitispneumonitis
osteomyelitisosteomyelitis
septic arthritisseptic arthritis
endocarditisendocarditis
necrotizing fasciitisnecrotizing fasciitis
toxic shock toxic shock--like syndromelike syndrome
hepatitishepatitis
thrombocytopeniathrombocytopeniahemorrhagic varicellahemorrhagic varicella
cerebellar ataxiacerebellar ataxia
encephalitisencephalitis
severe invasive group Asevere invasive group Astreptococcal infectionstreptococcal infectionincreases the risk increases the risk 4040--6060 foldfold
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PreventionPrevention
Live virus varicella vaccineLive virus varicella vaccine -- monovalent vaccinemonovalent vaccine
Measles, mumps, and rubella (MMR ) vaccineMeasles, mumps, and rubella (MMR ) vaccine
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PreventionPrevention
VZIG VZIG
Dose: 125 units/I0 kg, up to a maximum of 625Dose: 125 units/I0 kg, up to a maximum of 625units (five vials ), IM. Volume 125 units per 1.25 mlunits (five vials ), IM. Volume 125 units per 1.25 ml(one vial ).(one vial ).
Should be given within 96 hours of exposure,Should be given within 96 hours of exposure,preferably as soon as possiblepreferably as soon as possible
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Varicella Vaccine Varicella Vaccine
Oka strainOka strain
between 12 and 15 monthsbetween 12 and 15 months booster shot at 4 to 6 years of agebooster shot at 4 to 6 years of age
77--13 years13 years -- who have not had chickenpox may who have not had chickenpox may also receive the vaccine, with the two dosesalso receive the vaccine, with the two dosesgiven at least 3 months apart.given at least 3 months apart.
13 years who have not had either chickenpox 13 years who have not had either chickenpoxor the vaccine need two vaccine doses at least 1or the vaccine need two vaccine doses at least 1month apart.month apart.
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