Herpes Simplex Virus Type 1 (HSV-1): Incubation, Reactivation, and Management

HSV-1 (oral herpes) infects 67% of global population <50 years (WHO). Primary infection often asymptomatic; reactivation causes recurrent herpes labialis (cold sores).

Primary Infection

• Incubation: 2-12 days (mean 4 days)
• Symptomatic (10-30%): Gingivostomatitis (vesicles/ulcers on gingiva, tongue, lips), fever, cervical lymphadenopathy, malaise, dysphagia; resolves 10-14 days
• Asymptomatic: Silent seroconversion

Latency and Reactivation

• Virus retrograde transport → trigeminal ganglion → latent episomal DNA
• Triggers: UV exposure, stress, fever, menstruation, trauma, immunosuppression
• Anterograde transport → peripheral site → productive replication

Recurrent Episode Phases

1. Prodrome (0-24h): Tingling, burning, itching at site
2. Vesicular (1-3 days): Clustered vesicles on erythematous base (vermilion border)
3. Ulcerative (3-4 days): Vesicles rupture → painful ulcers (most infectious)
4. Crusting (4-7 days): Honey-colored crust; re-epithelialization
5. Healing (7-10 days): Complete without scarring (usually)

Treatment

Episodic Therapy (Start at Prodrome)

• Valacyclovir 2g BID × 1 day (FDA-approved)
• Famciclovir 1500mg single dose
• Acyclovir 400mg 5x/day × 5 days
• Topical: Acyclovir 5% cream, penciclovir 1% cream, docosanol 10% (OTC) — modest benefit

Suppressive Therapy (≥6 recurrences/year)

• Valacyclovir 500-1000mg daily
• Famciclovir 250mg BID
• Acyclovir 400mg BID
• Reduces frequency 70-80%, shedding 90%

Transmission Prevention

• Avoid contact during prodrome through crusting
• No kissing, oral sex, sharing utensils/towels during outbreak
• Suppressive therapy reduces asymptomatic shedding transmission by ~50%
• Condoms/dental dams for genital HSV-1 (increasing cause of genital herpes)

Complications

• Herpetic whitlow (finger), herpes gladiatorum (wrestlers), eczema herpeticum (AD), encephalitis (rare, temporal lobe), neonatal herpes (perinatal transmission)