Varicella and Herpes Zoster
Varicella-zoster virus (VZV) is a double-stranded DNA virus of the subfamily Alphaherpesvirinae, family Herpesviridae. It causes two distinct but closely linked conditions: chickenpox (varicella), the widespread primary infection usually seen in children, and shingles (herpes zoster), a localized reactivation of dormant virus in adults or people with weakened immunity.
After the initial chickenpox infection, VZV travels back along sensory nerve fibers and settles permanently in a latent state in the dorsal root ganglia or cranial nerve ganglia. When cell-mediated immunity weakens with age, stress or underlying illness, the virus starts replicating again, causing necrotizing inflammation of the ganglion, and travels down the nerve to the patch of skin it supplies (the dermatome).
At Haute-Derma, we diagnose and treat VZV infections to rigorous medical standards. Starting antiviral treatment within the first 72 hours not only speeds skin healing and minimizes the risk of pitted scars and dark marks, but is also key to preventing the most serious complication: postherpetic neuralgia (PHN).
Pathogenesis and Latency in the Nerve Ganglia
Primary Infection (Chickenpox)
- Transmission: VZV spreads through respiratory droplets or direct contact with blister fluid.
- Viral spread: The virus enters the upper respiratory mucosa, multiplies in regional lymph nodes, then causes a primary and a secondary viremia that carry it to the organs, especially the epidermis and mucous membranes.
- Skin lesions: The virus causes ballooning degeneration of keratinocytes, creating superficial intraepidermal blisters packed with viral particles.
Latency and Reactivation (Shingles)
- Establishing latency: From the chickenpox lesions, the virus travels back along sensory nerves to the nerve cell bodies in the dorsal root ganglia or cranial ganglia (such as the trigeminal ganglion).
- Reactivation: When VZV-specific CD4+ and CD45RA+ T cells fall below a protective level, the virus escapes immune control and replicates rapidly, causing necrotizing inflammation of the nerve and spreading to the skin it supplies, where it forms the characteristic band of blisters.
Clinical Features
Chickenpox (Varicella):
- Incubation: 10–21 days.
- Prodrome: low-grade fever, tiredness, poor appetite and headache.
- Eruptive phase: Red macules quickly turn into clear, droplet-like blisters on a reddened base, the classic "dewdrops on a rose petal" appearance.
- Key features: The blisters are scattered over the whole body, very itchy, and appear in successive crops, so lesions at every stage can be seen side by side: red macules, clear blisters, cloudy blisters, erosions and dry crusts.
Shingles (Herpes Zoster):
- Prodrome: Burning, aching, prickling or heightened sensitivity to pain (hyperesthesia) along one dermatome for 1–5 days before anything shows on the skin.
- Eruptive phase: A band of clustered blisters on red skin, confined to one side of the body and not crossing the midline.
- Special forms:
- Herpes zoster ophthalmicus: Involves the V1 branch of the trigeminal nerve. Hutchinson's sign (blisters on the tip of the nose) warns of a risk of corneal damage and vision loss.
- Ramsay Hunt syndrome: Shingles of the geniculate ganglion of the facial nerve (CN VII), causing blisters in the ear canal and on the eardrum, tongue ulcers, peripheral facial palsy and hearing loss.
- Postherpetic neuralgia (PHN): Severe stabbing or electric shock-like pain that lasts more than 3 months after the skin has fully healed.
Differential Diagnosis of Acute Blistering Rashes
| Chickenpox (Varicella) | Shingles (Herpes Zoster) | Cold Sores/Genital Herpes (Herpes Simplex) |
|---|---|---|
| Widespread, lesions at different stages | Band on one side of the body (dermatome) | Localized clusters (lips, genitals) |
| Dewdrop-like on a red base, fragile | Tense clustered blisters on red skin | Tiny grouped blisters that break into shallow ulcers |
| Intense itching predominates | Burning, aching nerve pain | Tingling, mild itch |
| Unvaccinated, exposure to an infected person | Older age, stress, weakened immunity | Mucosal contact, recurs at the same site |
Our Diagnostic Process at Haute-Derma
Clinical Examination and Dermoscopy:
- We ask about vaccination history, previous chickenpox and when the prodromal pain began.
- Dermoscopy: dome-shaped blisters with clear or faintly purulent fluid and a rim of dotted red vessels at the base.
Cytology and Molecular Testing:
- Tzanck smear: The blister base is scraped and Giemsa-stained to look for multinucleated giant cells.
- Real-time VZV PCR: Accurately detects varicella-zoster virus DNA in blister fluid when lesions are atypical or the patient is immunocompromised.
Assessing Complications:
- We check the V1 branch of the trigeminal nerve (looking for Hutchinson's sign) and arrange an urgent ophthalmology consultation if eye involvement is suspected.
- Pain is scored on the VAS scale so that we can plan ahead to prevent postherpetic neuralgia.
Management and Treatment at Haute-Derma
Antiviral Treatment and Systemic Pain Control
- Antivirals:
- Valacyclovir: 1000 mg by mouth three times daily for 7 days. Our preferred choice at Haute-Derma, as it reaches blood levels 3–5 times higher than acyclovir.
- Acyclovir: 800 mg by mouth five times daily for 7 days.
- Famciclovir: 500 mg by mouth three times daily for 7 days.
- Pain control and prevention of postherpetic neuralgia (PHN):
- Gabapentinoid nerve pain medications: gabapentin (300–900 mg/day) or pregabalin (75–150 mg/day), started within the first week of illness.
- Stepwise analgesia: paracetamol combined with tramadol for moderate to severe pain.
Local Care and Skin Recovery
- Disinfecting and drying the blisters: Apply nano-silver solution, octenidine dihydrochloride or 1% methylene blue twice daily. Never pop tense blisters.
- Red light / low-level laser therapy: Local treatment with 633 nm light helps reduce inflammation, speeds healing and helps ease nerve pain.
- Barrier repair and scar prevention: Once the blisters have crusted over, use a repair cream with ceramides, hyaluronic acid, vitamin B5 and niacinamide. For newly formed depressed scars, Haute-Derma uses long-pulsed 1064 nm Nd:YAG laser or gentle fractional CO2 laser to stimulate collagen and prevent unsightly scarring.
