Viral skin infection caused by Herpes Simplex Virus (HSV)
Aetiology
- HSV-1: commonly affects oral/labial area, facial skin.
- HSV-2: more common in genital region but can affect skin through contact.
Transmission:
- Direct skin-to-skin contact with active lesions.
- Asymptomatic viral shedding can transmit infection.
- Risk increases with mucosal contact, broken skin, sexual contact, and immunosuppression.
Pathophysiology
- Initial infection → virus replicates in epithelial cells → vesicle formation.
- Reactivation triggers:
- fever, stress, sunlight (UV), trauma, menstruation, immunosuppression.
- Virus travels to sensory nerve ganglia and becomes latent (trigeminal nerve for HSV-1, sacral nerve for HSV-2).
- Recurrence occurs at or near initial site.
Clinical presentation
Primary Infection
- May be asymptomatic or severe.
- Prodrome: tingling, burning, pain before rash.
- Clusters of vesicles on erythematous base, which rupture → erosions → crusting.
- Fever, malaise, lymphadenopathy possible.
Recurrent Herpes
- Milder and shorter duration than primary infection.
- Localized pain/tingling precedes lesion by hours–days.
- Vesicles recur at same site.
Investigations
Usually clinical, confirmed when needed.
Laboratory tests:
- Tzanck smear: multinucleated giant cells (not specific).
- Viral culture (gold standard for active lesion).
- PCR: sensitive and preferred for severe/disseminated cases.
- Direct fluorescent antibody (DFA).
- Serology for chronic/recurrent cases.
Management
First-line antiviral therapy
- Acyclovir 200 mg 5x1 / 400 mg 3x1
- Valacyclovir 500 mg 2x1
- Famciclovir 250 mg 3x1
Primary episode: 7–10 days
Recurrent episode: 3–5 days (start at prodrome for best effect)
Complication
Reye's Syndrome
- Associated with the administration of aspirin (salicylates) during viral illnesses.
- The condition is characterized by acute non-inflammatory encephalopathy and fatty degeneration of the liver and other organs.
- Primarily affects children
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