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1. Varicella-Zoster Virus

2. Varicella-Zoster Virus (VZV)
• Causes primary, latent, and recurrent infections.
• The primary infection: varicella (chickenpox)
• Followed by: lifelong latent infection of sensory ganglion neurons.
• Reactivation causes herpes zoster (shingles).
• Chickenpox causes morbidity and mortality which is more in:
- adolescents, adults
- immunocompromised
• Can be treated with antiviral drugs.
• Can be prevented by immunization.

3. ETIOLOGY
VZV
• Neurotropic human α-herpesvirus

4. EPIDEMIOLOGY
• Vaccine started in 1995
• Most children were infected by 15 yr.
• < 5% of adults remaining susceptible.
• Epidemics occurred in winter and spring,

5. • More serious in infants, adults, and
immunocompromised.
• Households transmission 65–86%;
• Contagious period from 2days before rash
until vesicles are crusted, usually 3–7 days
after onset of rash.
• Chicken pox can be acquired after close
contact with cases having herpes zoster

6. PATHOGENESIS
• VZV is transmitted in respiratory secretions and in the
fluid of skin lesions either by airborne spread or through
direct contact.
• Primary infection (varicella) results from inoculation of
the virus onto the mucosa of the upper respiratory tract
and tonsillar lymphoid tissue.
• virus replicates in the local lymphoid tissue then by
viremia spreads to the reticuloendothelial system.

7. • During viremia the mononuclear cells carry the virus
to form new crops of vesicles.
• Also goes back to upper respiratory mucosa during
the late incubation period, becoming infectious
before rash(2d).
• Host immune responses limit viral replication.
• In the immunocompromised continued viral
replication cause disseminated infection with
complications in the lungs, liver, brain, and other
organs.

8. PATHOGENESIS
• Virus is transported through sensory axons to the dorsal root ganglia
throughout the spinal cord, causing latent infection in the neurons.
• Subsequent reactivation of latent virus causes herpes zoster.
• The skin lesions of varicella and herpes zoster have identical
histopathology, and infectious VZV is present in both.
• Varicella causes humoral and cell-mediated immunity that is highly
protective against symptomatic reinfection.
• Suppression of cell-mediated immunity to VZV correlates with an
increased risk for VZV reactivation as herpes zoster

9. CLINICAL MANIFESTATIONS
• usually self-limited.
• may be associated with severe complications:
 bacterial superinfection
 Pneumonia
 Encephalitis
 bleeding disorders
 congenital infection
 life-threatening perinatal infection.
• Herpes zoster, uncommon in children, causes localized
cutaneous symptoms, but may disseminate in
immunocompromised patients.

10. Varicella (Chicken pox)
• I.P: 10 to 21 days
• The illness usually begins 14–16 days after exposure.
• Prodromal symptoms 24–48 hr before rash:
- Fever: moderate
- malaise
- anorexia
- headache
- mild abdominal pain (occasional).
• symptoms persist 1st 2–4 days after rash onset.

11. • lesions appear first on the scalp, face, or trunk.
• Initially: pruritic erythematous macules then papular
stage to form clear, fluid-filled vesicles.
• umbilication of the lesions begin in 24–48 hr.
• While the initial lesions are crusting, new crops form
on the trunk and then the extremities.
• presence of various stages at a time is characteristic
of varicella

13. • The rash is predominantly centripetal.
• Ulcerative lesions involving the mucosa of oropharynx,
eyelids and conjunctivae.
• The average lesions is 300, but healthy children(10-1500)
• The rash is more extensive with eczema.
• Hypopigmentation or hyperpigmentation of lesion sites
persists for days to weeks.
• severe scarring is unusual unless the lesions were secondarily
infected

18. The differential diagnosis
• herpes simplex virus,
• enterovirus,
• monkey pox,
• rickettsial pox
• S. aureus;
• drug reactions;
• contact dermatitis;
• insect bites.
Severe varicella was the most common illness confused with
smallpox before the eradication of smallpox.

19. Varicella in Vaccinated Individuals
• Vaccine is effective in;
- >95% preventing severe disease
- 80% preventing all disease.
• 1 of every 5 vaccinated children may develop varicella in school
outbreak.
• Mild disease with mild or no fever.
• The rash is atypical:
- maculopapular
- vesicles
- <50 lesions
• less contagious.

20. Progressive Varicella
• visceral organ involvement,
• coagulopathy,
• severe hemorrhage, and
• continued vesicular lesions, hemorrhagic
vesicles .
• Severe abdominal pain,
• The mortality rate is 7%; within 3 days after the
diagnosis of varicella pneumonia.

21. Risk factors for progressive varicella
1. congenital cellular immune deficiency.
2. malignancy, particularly on chemotherapy.
3. after organ transplantation
4. high-dose corticosteroids
• Immunization of the following gp helps to reduce the
problem:
- HIV-infected children who have a CD4 count > 15%
- children with leukemia and solid organ tumors who are
stable on maintenance chemotherapy.

22. Neonatal Chickenpox
• Newborns have high mortality in susceptible mother
contracting varicella around the time of delivery.
• Infants whose mothers develop varicella in the
period from 5 days prior to delivery to 2 days
afterward are at high risk for severe varicella.
• The infant acquires the infection transplacentally as a
result of maternal viremia, which may occur up to 48
hr prior to the maternal rash.
• Rash appears at the end of the 1st week.

23. Neonatal Chickenpox
• Because the mother has not yet developed a significant
antibody response, the infant receives a large dose of virus
without the moderating effect of maternal anti-VZV antibody.
• If the mother develops varicella > 5 days prior to delivery, she
still may pass virus to the soon-to-be-born child, but infection
is attenuated due to transmission of maternal antibody across
the placenta.

25. Neonatal Chickenpox ttt
• human varicella-zoster immune globulin (VariZIG) is indicated.
• Newborns whose mothers develop varicella 5 days before to 2 days after
delivery should receive 1 vial.
• Although neonatal varicella may occur in about half of these infants
despite administration of VariZIG, it is usually mild.

26. Congenital Varicella Syndrome
• up to 2% of fetuses whose mothers had varicella in the 1st 20
wk of pregnancy may have a VZV embryopathy.
• Fetuses infected at 6–12 wk of gestation appear to have
maximal interruption with limb development;
• fetuses infected at 16–20 wk may have eye and brain
involvement.
• The organs involved mainly the skin, extremities, eyes, and
brain
• The characteristic cutaneous lesion has been called a cicatrix,
a zigzag scarring, in a dermatomal distribution, often
associated with atrophy of the affected limb.

27. Stigmata of Varicella-Zoster Virus Fetopathy
DAMAGE TO SENSORY NERVES
• Cicatricial skin lesions
• Hypopigmentation
DAMAGE TO OPTIC STALK AND LENS VESICLE
• Microphthalmia
• Cataracts
• Chorioretinitis
• Optic atrophy

28. DAMAGE TO BRAIN/ENCEPHALITIS
• Microcephaly
• Hydrocephaly
• Calcifications
• Aplasia of brain
DAMAGE TO CERVICAL OR LUMBOSACRAL CORD
• Hypoplasia of an extremity
• Motor and sensory deficits
• Absent deep tendon reflexes
• Anisocoria (difference in pupil size)
• Horner syndrome
• Anal/urinary sphincter dysfunction

29. Diagnosis of VZV embryopathy
• The history.
• chickenpox stigmata seen in the fetus.
• Viral DNA may be detected in tissue samples by
(PCR).
• VZV-specific IgM antibody in the cord blood.
• Chorionic villus sampling

30. • Although varicella immune globulin to exposed
mother may not modify infection in the fetus.
• Similarly, acyclovir treatment may be given to the
mother with severe varicella.
• Acyclovir when the benefit to the mother outweighs
the potential risk to the fetus (effect is uncertain).
• antiviral treatment of infants with congenital VZV
syndrome is not indicated because it is not
progressive.

31. Herpes Zoster
• vesicular lesions clustered within 1 or less commonly
2 adjacent dermatomes
In the elderly:
• begins with burning pain, with clusters of skin lesions
in a dermatomal pattern.
• Almost half of the elderly with herpes zoster develop
complications;
• the most frequent complication is postherpetic
neuralgia, a painful condition that affects the nerves
despite resolution of the shingles skin lesions.

32. In children:
• rash is mild
• lesions appearing for a few days
• symptoms of acute neuritis are minimal
• complete resolution usually occurs within 1–2 wk.
• postherpetic neuralgia is very unusual in children.
• Approximately 4% of patients suffer a 2nd episode of herpes
zoster. ( 3 or more episodes are rare )
• Transverse myelitis with transient paralysis is a rare.
Risk factors:
• children who acquire varicella in the 1st year of life
• whose mothers have a varicella infection in the 3rd trimester
of pregnancy

34. Herpes Zoster
in immunocompromised children
• more severe, similar to adults, including postherpetic neuralgia.
• disseminated cutaneous disease like chicken pox.
• visceral dissemination with pneumonia, hepatitis, encephalitis, and
disseminated intravascular coagulopathy.
Patients with HIV:
• chronic or relapsing cutaneous disease
• Retinitis
• CNS disease without rash.
• A lower risk for herpes zoster in vaccinated children with leukemia.

35. DIAGNOSIS of Chicken pox

36. DIAGNOSIS of Chicken pox
• Leukopenia is typical during the 1st 72 hr; it is
followed by
• lymphocytosis.
• liver function tests usually (75%) mildly elevated.
• CSF: in CNS complications:
- lymphocytic pleocytosis
- increase in protein
- glucose concentration is usually normal.

37. • Quick direct fluorescence assay of cells from
cutaneous lesions,
• PCR.
• tissue culture.
• VZV IgG antibodies: 4-fold rise
• VZV-specific IgM assays

38. TREATMENT
• Antiviral modifies the course of both varicella
and herpes zoster (acyclovir).
• foscarnet is the only drug available for the
treatment of acyclovir-resistant VZV infections
(in HIV)
Acyclovir Therapy

39. • acyclovir therapy is not recommended routinely for treatment of
uncomplicated varicella in healthy child
• Oral therapy with acyclovir (20 mg/kg/dose, maximum 800
mg/dose) given as 4 doses/day for 5 days should be used to treat
uncomplicated varicella in:
(Indication of oral therapy) :
- nonpregnant individuals >13 yr
- children >12 mo with chronic skin or pulmonary disorders
- on steroids: short-term, intermittent, or aerosolized
- children receiving long-term salicylate therapy
- 2nd cases in household contacts.
Acyclovir Therapy

40. • To be most effective, treatment should be initiated as
early as possible, preferably within 24 hr of the onset
of the exanthem.
• There is clinical benefit if initiation of treatment is
delayed more than 72 hr after onset of the exanthem.
• Acyclovir does not interfere with VZV immunity.
• Intravenous therapy is indicated for severe disease
and for varicella in immunocompromised patients
(even after 72 hr duration of rash).
Acyclovir Therapy

41. Herpes Zoster ttt
• Antiviral drugs are effective for treatment of herpes
zoster.

42. COMPLICATIONS of Chicken pox
• mild varicella hepatitis is relatively common but rarely
clinically symptomatic.
• Mild thrombocytopenia occurs in 1–2% of children with
varicella and may be associated with transient petechiae.
• Purpura, hemorrhagic vesicles, hematuria, and
gastrointestinal bleeding .
• Cerebellar ataxia occurs in 1 in every 4,000 cases.
• Other: include encephalitis, pneumonia, nephritis, nephrotic
syndrome, hemolytic-uremic syndrome, arthritis, myocarditis,
pericarditis, pancreatitis, and orchitis

43. Bacterial Infections
• 2ry group A streptococci and S. aureus, in up to 5%.
• serious invasive infections caused by group A streptococcus, which can
have a fatal outcome
• The more invasive infections, such as varicella gangrenosa, bacterial
sepsis, pneumonia, arthritis,
• toxic shock syndrome.

44. Encephalitis and Cerebellar Ataxia
• Encephalitis: 1/50,000
• acute cerebellar ataxia: 1/4000
• morbidity more in < 5 yr or > 20 yr
• meningoencephalitis Encephalitis: neck rigidity,
altered consciousness, and seizures characterize.
• cerebellar ataxia: gradual gait disturbance,
nystagmus, and slurred speech.
• Neurologic symptoms usually begin 2–6 days after
onset of rash.

45. Encephalitis and Cerebellar Ataxia
• Clinical recovery is typically rapid, occurring within
24–72 hr, and is usually complete.
• severe hemorrhagic encephalitis is very rare.
• Reye syndrome of encephalopathy and hepatic
dysfunction associated with varicella has become
rare since salicylates are no longer routinely used as
antipyretics

46. PROGNOSIS of Chicken pox
• mortality rate of 3 per 100,000 cases.
• lowest fatality 1–9 yr.
• infants have a 4 times greater risk of dying
• adults have a 25 times greater high risk of dying.
• the most common complications among people who
died from varicella were pneumonia, CNS complications,
secondary infections, and hemorrhagic conditions.
• mortality in immunocompromised children: 7–14%,
• mortality in immunocompromised adults: 50%

47. PREVENTION
• VZV transmission is difficult to prevent
because the infection is contagious for 24–48
hr before the rash appears.
• All health care workers should have
documented VZV immunization.

48. Vaccine
• Live virus varicella vaccine: alone or combined with
MMR (MMRV).
• Administration of varicella vaccine within 4 wk of
MMR vaccine has been associated with a higher risk
for severe disease;
• therefore, it is recommended that the vaccines
either be administered simultaneously at different
sites or be given at least 4 wk apart.

49. Vaccine
• Varicella vaccine is recommended for routine
administration to children at 12–18 mo and at
4–6 yr of age.
• Vaccination with 2 doses, separated by at least 4 wk,

51. Vaccine contraindication
• Varicella vaccine is contraindicated in children
with cell-mediated immune deficiencies,
• Can be given to children with acute
lymphoblastic leukemia who are in remission,
and for HIV-infected children with specific
guidelines.
• Children with isolated humoral immune
deficiencies may receive VZV vaccine.

52. Post-exposure Prophylaxis
• Vaccine given to normal children within 3–5 days
after exposure is effective in preventing or modifying
varicella.
• Oral acyclovir administered late in the incubation
period may modify varicella.
• High-titer anti-VZV immune globulin as postexposure
prophylaxis is recommended for:
- immunocompromised children,
- pregnant women, and
- newborns exposed to maternal varicella.