Flashcards in skin 5: chicken pox Deck (51):
Chickenpox (varicella) is ??
affects what age group??
a highly contagious, generalized vesicular exanthematous disease of seasonally epidemic propensity caused by varicella-zoster virus (VZV)
*mild, self-limiting childhood disease, but it does cause significant morbidity and mortality in some children (i.e., immune compromised) and especially in adults*
Shingles (zoster) is a ??
disease caused by a recrudescence of the same virus as chicken pox.
VZV, like all herpesviruses, is a latent virus.
an alpha herpesvirus (enveloped, dsDNA virus which encodes its own thymidine kinase) with one serotype.
VZV is closely related to HSV-1 and HSV-2
large, enveloped dsDNA viruses.
-possess a unique gene that encodes for thymidine kinase that activates herpes antiviral agents and allows for targeting by the drugs.
-8 different herpesviruses are known to infect humans, the sole host and reservoir.
-numerous other herpesviruses infect other primates, cows (bovine), etc. that may be occasional or accidental pathogens for humans.
8 different HHVs
Human Herpesvirus-1 = HHV-1, Herpes simplex virus (HSV)-1; α group)
Human Herpesvirus-2 = HHV-2, Herpes simplex virus (HSV-2; (α group)
Human Herpesvirus-3 = HHV-3, Varicella-Zoster Virus (VZV; (α group)
Human Herpesvirus-4 = HHV-4, Epstein-Barr Virus (EBV; γ group)
Human Herpesvirus-5 = HHV-5, Cytomegalovirus (CMV; β group)
Human Herpesvirus-6 = HHV-6 (β group)
Human Herpesvirus-7 = HHV-7 (β group)
Human Herpesvirus-8 = HHV-8 (Kaposi sarcoma associated herpesvirus; γ group)
Humans are the only host. Carrier state
1 -6 years-of-age. Approx. 5% of adults are susceptible
winter and early spring
POE is the URT or conjunctiva, spread via direct contact with respiratory secretions (primary) and secondary POE is skin lesions
when no longer contagious?
highly contagious –Primary attack rate >90% and secondary attack rate is 80%.
most contagious 1 to 2 days before rash appears to 4 to 5 days after.
*Once scabs have formed on all lesions and there are no new lesions, the patient is no longer infectious*
Re-infection is rare and the course tends to be milder.
Zoster (aka belt, girdle, shingles) common??
can be a source of ??
Common. 500,000-750,000 cases per year in the U.S and the incidence is rising as immunosuppressed population increases.
The zoster (shingles) patient can be the source of chickenpox outbreaks in a community.
no seasonality because this is a reactivated infection.
Zoster: predisposing factors, occurs in who?
Adults, with the highest rate among those over 60 years-of-age.
For 30% of zoster pt., there is no known predisposing factor.
VZV: incubation period??
14 to 16 days; range is 10 to 21 days
Initial VZV multiplication occurs in the ??, then the ??;
then resulting in a ?? 4-6 days following infection
mucosa of the URT
draining lymph nodes
During the primary viremia, the VZV infects and replicates in ??
lymphoid tissue in the liver, spleen and possibly other organs.
Secondary viremia occurs about 10 to 14 days post-infection and is coincident with the appearance of ??
?? are found in lesions.
There are 5 to 6 temperature spikes and each coinciding with the appearance of ??
fever and a vesicular rash.
Both *virus and antibody complexes*
a new set of lesions.
The *virus becomes latent* in ?? after primary infection.
Rarely, the virus will travel up arteries to the brain causing an ??
dorsal root or cranial nerves (trigeminal ganglia)
ischemic stroke: 1 child/15,000 with chickenpox.
Clinical Manifestations: Varicella: prodrome??
Prodromal symptoms are usually absent in the young.
In older children and adults there is a prodrome of flu-like symptoms 24-48 hours prior to rash
Varicella: symptoms during primary disease
mild to high fever; malaise, anorexia, headache, vomiting and rash.
Varicella: rash appears first??
what type of pattern??
first on the on head (scalp sometimes, face) or trunk and becomes generalized,
but is more severe on head and trunk than on the extremities (*centripetal pattern*)
Varicella rash characteristics: starts out as ?? then within hours become ??
Within 24-48 h, vesicles become ??
New vesicular lesions occur over the next ?? days
corresponding with ??
starts out as a pruritic, red, maculopapular rash then within hours, each lesion is a small, thin-walled *vesicle* on a maculopapular base (*dew drop on a rose petal*).
pustular, crusted, then scabbed.
3-6 days, corresponding with each fever spike, so that at any given time, *all stages of the skin lesions are visible for some time*
Varicella: more lesions
Painful, ulcerative lesions occur on mucous membranes of oropharynx, conjunctiva, vagina.
patient is infectious until all lesions have scabbed and no new lesions are visible.
Varicella Lesions can scar if they become ?? by what ??
the most common reason for hospitalization of children with varicella ??
secondarily bacterial infected - impetiginized by group A Strep (GAS, Streptococcus pyogenes) or by Staphylococcus aureus and form a honey-colored crust over the lesion.
*is this complication* It is rare for scarring to occur in non-impetiginized lesions.
Varicella Re-infection: Occurs in about ??
5% of all cases usually in persons whose first infection was a mild case as a young child.
Genetics is a factor. Some have asymptomatic or mild infections and will seroconvert. Later in life, they may report having not had chickenpox but will be seropositive and may develop zoster.
Varicella Adult infection: more or less severe than in children??
typically have 1+ of the following:
Interstitial pneumonia (20 to 30% of adults)
Varicella maternal disease: when is neonate at high risk for severe VZV infection??
4 to 5 days pre-partum to 2 to 3 days post-partum
Maternal Varicella manifestation
During primary infection or with recrudescence (herpes zoster), a disseminated infection involving all tissues and organs can occur that can be fatal. The lesions are hemorrhagic, i.e. non-blanching
Herpes zoster is a recrudescence or reactivation of latent VZV infection due to
when this occurs, the virus follows the nerve pathway to a dermatome following ?? from ??
waning cell-mediated immunity (CMI) to VZV later in life or during immunosuppression.
reverse axoplasmic flow from the dorsal root ganglion (DRG)
Herpes zoster risk factors
The *suppressed CMI* allows ??
how is the virus limited in its spread ??
Age, disease, drug-induced reduction CMI, environmental stress, etc
reactivation/proliferation of VZV causing neuronal destruction, inflammation and pain at the site.
The virus is probably limited in its spread and does not disseminate because antibody prevents it.
The zoster pt.: infectious??
The zoster pt. is infectious. The disease contracted from a zoster patient is varicella, not zoster.
zoster initial clinical presentation
Initially tingling sensation or pin-prick sensations followed later by severe pain in areas innervated by the nerve (usually precedes by hours or days)
zoster: rash follows tingling: characteristics??
The rash is an asymmetrical maculopapular or vesicular-crusting rash following a single thoracic dermatome or cranial nerve distribution.
1. Flu-like symptoms may be present.
2. Pain: acute herpetic neuralgia that lasts for approx.. 30 days after onset of the rash
Ophthalmic or ocular zoster and herpes zoster oticus (involving the geniculate
ganglion, i.e., the ear) must be referred to appropriate specialist as a medical
More severe, widespread rashes occur in immunosuppressed individuals.
Zoster complications: Postherpetic neuralgia -
may last how long?
more common in who?
a severe burning, lancinating pain, can be debilitating, typically accompanied by allodynia (pain from non-noxious stimuli).
It may persist for >120 days (4mos!) after the rash has healed and occurs in 10% of all cases but at a much higher incidence in those ≥60 y-o-age.
more Zoster complications related to postherpetic neuralgia:
Acute peripheral facial palsy and idiopathic peripheral facial palsy -
Reactivation of either VZV (Zoster or Zoster Sine Herpete [No rash]) or HSV, Lyme disease, etc.
Unilateral facial paralysis resulting from demyelination by VZV or HSV of the trigeminal nerve, geniculate ganglion of the 7th cranial nerve, the 2nd or 3rd cervical roots or the 5th cranial nerve.
Zoster complication: Ramsey-Hunt syndrome:
also, VZV may also soon be added to the growing list of triggers for ??
Acute facial palsy and/or ipsilateral facial palsy plus herpes zoster oticus (board question?).
Other syndromes involving VZV: Congenital varicella syndrome
when is fetus at risk? mother?
only risk to mothers with??
VZV can cross the placenta and infect the child in utero
-2% risk of severe VZV infection if fetus is infected during first 20 weeks
-Pregnant mother is at great risk, especially if she is infected in the last
-Only risk is to seronegative mothers with no history of
Can be prevented if varicella-zoster immune globulin (VZIG) is provided
within 72 to 96 hours of exposure
Clinical criteria are usually sufficient
VZV Laboratory diagnosis.
Presence of multinucleated giant cells with intranuclear inclusions (syncytia formation with Cowdry type A intranuclear inclusions) are present in skin lesions, respiratory specimens or organ biopsies.
DFA or Tzanck smear of scraping from the base of the lesion can also be diagnostic.
Virus can be isolated from the lesions using mammalian cell culture – not routine.
VZV dx: serologic testing used to ??
Especially important in ??
who should be vaccinated??
establish immune status in adults.
-pregnant women who have been exposed and prior to clinician training and rotations for health professional students.
If there is no history of chickenpox, and no history of infection as indicated by the presence of antibodies, you should get vaccinated.
tx for immunocompetent children with varicella:
-lotion or antihistamines for pruritus.
-ASA is contraindicated (Reye's syndrome- also
associated with influenza virus and essentially any febrile illness of childhood) -Acetaminophen or other antipyretics are recommended during childhood.
- pooled globulin from selected population of donors with higher anti-VZV titer
VZIG is recommended for persons who fulfill all 3 requirements :
-VZV susceptible (as determined by seronegativity)
-Exposure to VZV is likely to result in VZV infection
-At increased risk for complication compared to general population, i.e.,
adolescents, adults or immunosuppressed children with specific leukemia,
VZIG: must be administered within ??
can VZIG be used as tx?
72-96 h (3-4 days) post-
exposure to obtain full or partial protection.
-NOT a treatment for any type of VZV infection or disease.
Varicella Antiviral and palliative therapy:
effective when administered ??
Only recommend for ??
Oral acyclovir administered 9 days or fewer post-infection can prevent/minimize
signs and symptoms of disease.
If administered within 24 h of onset of varicella symptoms is also efficacious.
-Only recommend for persons at high risk for severe disease, because widespread usage increases risk of thymidine kinase mutation and thus resistance.
Zoster Antiviral and palliative therapy:
Must administer within ??
Acyclovir, Famciclovir, Valacyclovir are licensed for modification/treatment of zoster.
-72 h (3 days) of onset of rash to reduce degree and duration of pain.
Postherpetic neuralgia tx:
Nortriptyline (a tricyclic antidepressant)
Lidocain patch, 5%
Gabapentin (anticonvulsant - analgesic)
Opioid analgesics (e.g., sustained release oxycodone)
Nucleoside analog (acyclovir, famciclovir, valacyclovir, brivudin)
VZV prevention, vaccine??
given to who and with what else??
more or less effective than WT chicken pox ?
*Live attenuated vaccine (Varivax®)*
Children 13 months to 12 years-of-age and in susceptible adolescent and adult populations and administered on same schedule as MMR vaccine. *Significantly reduced risk compared to a child who develops wild type chicken pox*
Efficacy is high with 1 dose in children, 2 doses in adolescents, adults.
90% effective against moderate-to-severe varicella and 56% effective in preventing mild varicella
Some recent evidence suggests that children immunized before ?? can acquire chickenpox if exposed at a later date, though the infection course, signs and symptoms are less than if not immunized
18 months, and especially those 14 months of age
Transmission of vaccine strain??
Some anergy. However, in all cases, symptoms are extremely mild, no significant VZV sequelae occur, immunity to both vaccine and wild-type strain is boosted.
Transmission of vaccine strain to susceptible persons is extremely rare.
Breakthrough chickenpox is most likely >5 years post-vaccination unless
immunized at 14 months in which case, it can occur sooner
Other recommendations for VZV vaccination
-3 -5 days post-exposure to prevent/ameliorate disease potential for immunocompetent persons.
-Persons with humoral immunodeficiencies.
-Has been efficacious in preventing zoster
contraindications for VZV vaccination
Pregnant women, women planning to become pregnant in next 3 months.