DermatologyTier 1Disease (DEADMAN)

Viral infections - herpes simplex virus

Description

HSV-1: classically orolabial ("cold sores"), increasingly also genital via oral sex
HSV-2: classically genital, higher recurrence rate than HSV-1 at the same site
Primary infection often more severe/systemic than recurrent episodes

Extremely common - most adults are HSV-1 seropositive; HSV-2 seroprevalence lower but substantial
Neonatal herpes - rare but serious, risk highest with primary maternal infection near delivery

Primary infection at mucocutaneous site -> latency in sensory ganglia (trigeminal for orolabial, sacral for genital)
Reactivation triggered by stress, illness, UV exposure (orolabial), immunosuppression, menstruation
Asymptomatic viral shedding occurs between clinical episodes and contributes to transmission

Clinical - grouped vesicles on an erythematous base, painful, progressing to ulceration/crusting
PCR from vesicle/ulcer swab - most sensitive, distinguishes HSV-1/2
Type-specific serology in select scenarios (asymptomatic partner risk assessment, atypical presentation)

First/primary episode: oral aciclovir/valaciclovir/famciclovir - reduces duration/severity, most effective started early
Recurrent episodes: episodic therapy (short antiviral course at prodrome/onset) for infrequent recurrences; suppressive daily therapy for frequent recurrences (>=6/year) or to reduce transmission risk to a partner
Eczema herpeticum: widespread vesicles on eczematous skin + systemic upset - dermatological emergency, IV aciclovir
HSV encephalitis: IV aciclovir empirically while awaiting CSF PCR - do not delay treatment
Pregnancy: suppressive therapy from 36 weeks if history of genital herpes, reduces recurrence/shedding at delivery; primary genital HSV near term may warrant caesarean section to prevent neonatal transmission

Eczema herpeticum (superinfection of atopic dermatitis)
HSV encephalitis (temporal lobe predilection) - rare but high mortality/morbidity if untreated
Neonatal herpes - high morbidity/mortality, disseminated or CNS disease
Erythema multiforme - HSV is the commonest identifiable trigger

Lifelong latency with intermittent reactivation; recurrence frequency typically decreases over years
Most recurrences are milder and shorter than the primary episode
Suppressive therapy substantially reduces both recurrence frequency and asymptomatic shedding/transmission risk

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