Herpes Simplex

Definition

• Herpes simplex virus (HSV) is a common viral infection causing localised blistering (vesicles on an erythematous base). Infection may recur with triggers such as stress, illness, or sun exposure.

Aetiology

• HSV-1: Primarily oral/facial infections (cold sores)

• HSV-2: Primarily genital lesions

• Latency: HSV remains dormant in nerve ganglia, reactivated by triggers (stress, fever, trauma)

Presentation

• Cold Sores / Fever Blisters: Common around lips, nose, chin

• Genital Sores: HSV-2 or occasionally HSV-1 via oral–genital contact

• Any Skin/Mucosal Surface: In immunocompromised or during autoinoculation

Primary Infection

• Fever, malaise, regional lymphadenopathy

• Painful blisters or ulcers (oral, genital) – can affect eating, swallowing, urination

• More severe presentation than recurrent episodes

Recurrent Infection

• Clusters of vesicles on an erythematous base

• Typically milder than primary infection

• May have local lymphadenopathy, prodromal tingling/burning

Differential Diagnosis

• Aphthous ulcers (usually non-vesicular, occur on non-keratinised mucosa)

• Hand–foot–and–mouth disease (Coxsackie virus, typically in children)

• Syphilis (genital chancre, classically painless)

• Varicella-zoster (shingles): dermatomal distribution

Diagnosis

• Clinical: Characteristic vesicles, ulcers, distribution

• Laboratory: PCR or viral culture if definitive diagnosis needed (e.g. atypical lesions, immunocompromised patients)

Management

Mild Oral Mucocutaneous Herpes

• Topical Anaesthetics: Benzydamine 1% gel or lidocaine 2% solution to ease pain

• Supportive Care: Keep lesions clean, consider analgesics (e.g. paracetamol, NSAIDs)

Severe Initial Episode

• Adults: Famciclovir 500 mg BD or Valaciclovir 1 g BD for 7 days

• Children >3 months: Aciclovir (weight-based) for 5–7 days

Recurrent Infection

• Mild:

  • Topical aciclovir or penciclovir to reduce symptoms/duration

  • Oral famciclovir (e.g. 1 g stat) for herpes labialis

• Severe/Frequent Recurrences:

  • Daily prophylaxis with famciclovir or valaciclovir for up to 6 months

Prevention

• Sunscreen on lips/face to reduce sun-triggered herpes labialis

• Antivirals (e.g. low-dose aciclovir, valaciclovir) for recurrent frequent outbreaks

• Avoid contact with active lesions, practise safe sex (especially for genital HSV)

Complications

• Eye Involvement: Conjunctivitis, herpetic keratitis (corneal ulcers)

• Throat: Severe pharyngitis, odynophagia

• Skin: Eczema herpeticum (widespread HSV in atopic dermatitis)

• Erythema multiforme triggered by recurrent HSV

• Neurological: Rare paralysis, HSV meningitis

• Disseminated Infection: Potentially severe in immunocompromised patients