Contents
Varicella zoster virus is one of the herpesviruses and it causes two diseases – varicella or chickenpox, and herpes zoster also known as shingles.
- Naturally infects humans
- No animal reservoir
- Main targets: T lymphocytes, epithelial cells and ganglia
Epidemiology

- Worldwide incidence and is endemic in populations of sufficient size to sustain year-round transmission, with epidemics occurring every 2–3 years.
- Strong seasonal pattern (peak incidence during winter and spring or during the cool, dry season)
Microbiology
Varicella-zoster virus (VZV, also known as human herpesvirus 3) is a ubiquitous alphaherpesvirus with a double-stranded DNA genome.

Presentation
Disease course:
- Varicella (chickenpox) infection
- Latent phase
- Zoster (shingles)

Varicella (Chickenpox)
Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with Varicella-Zoster virus (VZV).

Maculopapular rash and vescicles
Diffuse prurititic, vescicular rash most priminent on face and chest that appears 24-48 hr after the prodromal symptoms as intensely pruritic erythematous macules. Rash becomes non-contageous after crusting of lesions

Herpes zoster (Shingles)
Shingles, also known as herpes zoster, is a viral disease characterised by a painful skin rash with blisters in a localised area.


- Affected dermatome (eg. Thoracic dermatome (M/C)):
- Burning discomfort
- Discrete vesicles (3-4 days later)
Complications

Cutaneous complications:
Seen in both chicken pox and shingles
- Secondary bacterial infections of the skin lesions (common)
- Necrotizing fasciitis (rare)
Neurologic complications:
- Cranial nerve palsy
- Myelitis
- Encephalitis
- Granulomatous cerebral angiitis: Cerebrovascular complication leading to stroke-like syndrome in association with shingles (esp. in ophthalmic distribution)
- Post-herpetic neuralgia (M/C): Persistence of pain for ≥ 1-6 months following healing of rash
- Geniculate ganglion:
- Ramsay Hunt syndrome/Herpes zoster oticus
- TRIAD: Ipsilateral facial paralysis + Ear pain + Vescicles (on face, on/in the ear)
- Ramsay Hunt syndrome/Herpes zoster oticus
- Sacral nerve root involvement:
- Bowel & bladder dysfunction
Ramsay Hunt syndrome:
Shingles in ophthalmic division of Trigeminal
- Vescicles on cornea → Ulceration → Blindness
- URGENT OPHTHALMOLOGY REVIEW required
Progressive varicella syndrome
Seen in immunocompromised individuals
- Continued development of lesions
- Hemorrhagic lesions
- Coagulopathy and visceral organ involvement (including hepatitis, pneumonia and encephalitis)
Congenital varicella syndrome
Following infection in the 1st & 2nd trimester at a frequency of 0.4-2%
- Cicatrix: Characteristic zigzag skin scarring in a dermatomal distribution
- Malformed extremities
- Cataracts and brain abnormalities (e.g. aplasia, calcifications)
- If the disease occurs in the mother 5 days before to 2 days after delivery: Severe and often fatal neonatal disease
Diagnosis
- In atypical cases,
- Diagnosis is made on Tzanck smear of the lesions
- Shows multinucleated cells
- IgM antibodies to varicella
- Diagnosis is made on Tzanck smear of the lesions
Differential diagnosis:
- Vesicular exanthemata (eg. Herpes simplex)
- Enteroviral infections (hand-foot-mouth disease)
- Insect bites
- Drug reactions

Management
Symptomatic management:
- Antipyretics
- Antipruritic agents
- Good hygiene
Medical management:
Aspirinis contraindicated due to the risk of Reye syndrome. Management of shingles is same as chickenpox but with duration of 7-10 days
- Adult/child:
- Oral aciclovir 800mg 5 times daily for 5 days
- Famciclovir 500mg 3 times daily for 5 days
- Valaciclovir 1g 3 times daily for 5 days
- Immunocompromised/pregnant host:
- IV Aciclovir 5mg/kg daily
- If improves, switch to oral therapy
- IV Aciclovir 5mg/kg daily
Post-exposure prophylaxis:
- Varicella zoster immune globulin (YZIG)
Prevention:
- Live attenuated vaccine (Oka strain)
