Infectious Disease

Herpes Simplex Virus Infection

Herpes simplex virus causes recurrent painful mucocutaneous lesions and can also cause sight-threatening keratitis, encephalitis, eczema herpeticum, neonatal disease and disseminated infection; management depends on site, severity, host, pregnancy and timing.

In a nutshell

HSV usually causes recurrent painful mucocutaneous lesions, but genital ulcers need PCR and STI assessment and serious-site disease needs urgent systemic treatment. Use oral antivirals for a first genital episode and selected recurrences, suppressive therapy for frequent or distressing disease or transmission reduction, and urgent specialist-led antiviral treatment for keratitis, eczema herpeticum, encephalitis, neonatal, disseminated or immunocompromised infection.

Classic presentation

A patient with recurrent painful grouped vesicles or shallow ulcers on the lip or genitals, often preceded by a tingling prodrome; serious-site clues are eye pain or photophobia, neurological change, rapidly worsening painful eczema or a sick neonate.

Key points

HSV remains latent in sensory ganglia; antivirals suppress but do not eradicate infection.
Genital HSV-1 and HSV-2 overlap; use lesion PCR/NAAT and do not infer the type from the site.
A first genital episode merits prompt oral antiviral treatment and sexual-health review.
Suppressive antivirals reduce recurrences and can reduce transmission risk but do not eliminate asymptomatic shedding.
Eye disease needs urgent ophthalmology; suspected encephalitis, eczema herpeticum, neonatal or disseminated disease needs immediate systemic aciclovir and specialist care.
Genital ulcers need syphilis and other STI consideration; pregnancy needs the joint BASHH/RCOG pathway.

First-line investigation

Clinical examination plus lesion PCR/NAAT for genital or atypical lesions; add STI testing and escalate urgently for eye, CNS, neonatal, disseminated or immunocompromised disease.

Management

Identify serious-site disease

Escalate eye pain or visual change, neurological symptoms, rapidly worsening painful eczema, neonatal sepsis-like illness, disseminated lesions, hepatitis-like illness or severe immunocompromised disease.^2,9,8,6,5
Start urgent systemic aciclovir when encephalitis, eczema herpeticum, neonatal, disseminated or severe immunocompromised HSV is suspected; do not wait for PCR if this would delay treatment.^7,8,6,13

Confirm the lesion and host context

Use validated HSV PCR/NAAT from a fresh genital or atypical lesion, with typing where it affects counselling, pregnancy or recurrence expectations; consider syphilis, HIV and other STI testing.^1,5,10
Do not use non-type-specific serology or HSV IgM to diagnose an acute lesion; use type-specific serology only in selected specialist-led situations.^1,5

Treat uncomplicated mucocutaneous disease

Offer prompt oral antiviral therapy for a first genital episode and provide analgesia, hydration, saline bathing, sexual-health review and counselling.^1,13
Use supportive or early episodic antiviral treatment for recurrent orolabial or genital disease, and discuss daily suppression for frequent, distressing or transmission-related recurrences.^1,14,13

Use site-specific specialist pathways

Refer suspected keratitis urgently to ophthalmology for antiviral eye treatment; topical steroids require ophthalmic supervision and antiviral cover.^2,3,16
Use immediate IV aciclovir and specialist pathways for encephalitis, severe eczema herpeticum, neonatal, disseminated or immunocompromised infection, with renal monitoring and resistance assessment if treatment fails.^7,5,6,11

Prevent transmission and plan pregnancy care

Advise no sexual contact during lesions or prodrome, disclose to partners, use condoms with the understanding that they do not eliminate risk, and discuss suppressive therapy and HIV/STI testing.^1,4
In pregnancy or at delivery, involve GUM, obstetrics and neonatology early and document a delivery and neonatal plan based on timing of acquisition, lesions and specialist assessment.^5,13,12

Exam traps

Do not treat a dendritic corneal ulcer with topical steroids alone.
Eczema herpeticum needs immediate systemic antiviral treatment and same-day specialist review, especially near the eye.
HSV encephalitis treatment should start before CSF PCR results return when suspicion is strong.
Genital HSV-1 is common, so HSV-1 does not mean a lesion is necessarily oral.
Avoid sex during lesions or prodrome; condoms and suppressive antivirals reduce but do not eliminate transmission.
A neonate may have HSV without fever or skin lesions; keep the threshold for specialist testing and treatment low.

Illustrations

Herpes labialis with vesicular and crusted lesionsA clinical photograph showing multiple herpes labialis lesions around the upper lip and nostril, including small vesicular and crusted areas.WizardOfOz, Wikimedia Commons · CC-BY-SA-4.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.