Chickenpox. Differential diagnosis in patients with vesicular rash.

Question 1

what is the EPIDEMIOLOGY OF CHICKEN POX?

Answer 1

Primarily occurs in children - and extremely contagious infection

ubiquitous

more frequently in adults who reside in tropical regions

occurs seasonally and in epidemics - more common in late winter and early spring

humans are the only reservoir for VZV

recurrence of infection can occur- recurrence of infection

Question 2

what are the CHARACTERISTICS OF VARICELLA ZOSTER?

Answer 2

alpha herpesvirus (DNA virus) that causes chickenpox and herpes zoster

Question 3

how is VARICELLA ZOSTER TRANSMITTED ?

Answer 3

respiratory droplets and direct contact with lesion

transplacental

Question 4

what is the INCUBATION PERIOD OF VARICELLA ZOSTER

Answer 4

14/15 days (range of 10 to 20 days)

Question 5

INFECTIOUS PERIOD OF VARICELLA ?

Answer 5

patients are infectious for a period of approximately 48 hours before the period of vesicle formation and generally for 4 to 5 days there after until all vesicles are crusted

Question 6

PATHOGENESIS OF VARICELLA?

Answer 6

replication of the virus at undefined site, which usually is at the nasopharynx

seeding into the lymphatic and/ or reticuloendothelial system

developtment of viremia

Latency: can become latent after primary infection and reside inside
Dorsal root ganglia
Trigeminal ganglia

Question 7

what are the CLINICAL MANIFESTATIONS OF VARICELLA?

Answer 7

prodromal face
1-2 days

fever malaise
more common in adults
less typical in children - rash seen first

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exanthema phase lasts 6 days

widespread rash starting at trunk
spreading to the face, scalp, and extremities

Simultaneous occurrence of various stages of rash: erythematous macules → papules → vesicles filled with a clear fluid on an erythematous base → eruption of vesicles → crusted papules/ scabs → hypopigmentation of healed lesions

Severe pruritus

Question 8

what are the CLINICAL FORMS THE DISEASE ?

Answer 8

Mild forms

Severe forms:
•
Varicella hemorrhagica
•
Varicella necrotica

Fulminant and hyperoxic varicella
•
Varicella bullsa

Question 9

what are he COMPLICATION OF VARICELLA ZOSTER ?

Answer 9

econdary bacterial
infection of the skin -> usually caused by Streptococcus
pyogenes or Staphylococcus aureus
-
Varicella pneumonitis (life- threatening; more common in
young adults and immunocompromised)
-
Myocarditis
-
Corneal lesions
-
Nephritis 

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in pregnancy: has a high death rate when when maternal disease
develops 5 days before delivery or up to 48 hours postpartum

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congenital varicella

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Herpes Zoster
-
a sporadic disease that results from reactivation of latent VZV from
dorsal root ganglia

-
common infection in elderly and immunocompromised (AIDS)

patients >50 years of age

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without skin lesion, the disease is called Zoster sine herpatica

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if the ophthalmic branch of the trigeminal nerve is involved ->
zoster ophthalmicus
develops, which can lead to
blindness
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RAMSAY- HUNT SYNDROME
= pain and vesicles within the external auditory canal -> loss of
taste in the anterior two-thirds of the tongue
while developing ipsilateral facial palsy
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extracutaneous involvement:
meningoencephalitis, encephalitis or
granulomatous cerebral angiitis, transverse
myelitis

Question 10

CLINICAL MANIFESTATION OF HERPES ZOSTER/ SHINGLES?

Answer 10

characterized by a unilateral vesicular eruption with a dermatomal
distribution (localized rash) often with pain
-
thoracic or lumbar dermatomes are most commonly involved (T3-L3!!)

acute neuritis and, later, PHN
PHN = post herpatic neuralgia

-
The pain can be divided into 3 stages: acute, subacute and chronic
-
constant, stabbing pain in the involved dermatome, and
is worse at night
-
the lesion is a erythematous maculopapular rash that evolves rapidly
into vesicular lesions

Question 11

DIAGNOSIS OF VARICELLA ZOSTER?

Answer 11

isolation of VZV in susceptible tissue-culture

FAMA (= Fluorescent Antibody to membrane antigen) test
-
Immune adherence haemaglutination
-
ELISA
-
Tzanck smear, with scraping of the base of the lesions in an attempt
to demonstrate multinucleated giant cells
-
-> FAMA and ELISA appear to be the most sensitive

Question 12

dd of vzv?

Answer 12

disseminated HSV,
coxsackievirus infection, echovirus infection, atypical measles,
disseminated enteroviral infection, Rickettsialpox, Monkeypox or
smallpox (but larger lesions than in chickenpox

Question 13

TREATMENT VZV?

Answer 13

acetaminophen should be used to reduce fever
-
analgesics: Gabapentin, pregabalin, lidocaine, and Fluphenazine
hydrochloride (for the PHN)
-
Glucocorticoids with antiviral medications like acyclovir
-
In immunocompromised patients: IV acyclovir for 7 days
-
Varicella pneumonia -> ventilatory suppor

Question 14

prevention of vzv?

Answer 14

1. live attenuated varicella vaccine (Oka)
   for all children >1 year of
   age up to 12 years of age who have not had chickenpox
   and adults who are seronegative to VZV

For children, 2 doses -> first at 12–15 months of age

second at ~4–6 years of age

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when being >13 years of age, they should receive two doses of vaccine at least 1 month apart
-
VZV vaccine with 18 times the viral content of the Oka vaccine in adults >50 years of age

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2. varicella-zoster immune globulin (VZIG) in susceptible patients who
   may develop complications of varicella, and have had a significant
   exposure;
   given within 96h of exposure

Indications:
Pregnant women with no evidence of immunity

Immunosuppressed individuals with no evidence of immunity

Newborn infants, if the mother was infected 5 days before or up to 2 days after birth
Premature babies
> 28 weeks if the mother has no evidence of immunity
< 28 weeks regardless of mother’s immunity status
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3. antiviral therapy can be given as prophylaxis to individuals at high
   risk (instituted 7 days after intense exposure)