16th July 2026

Herpes Simplex Virus

Herpes simplex virus (HSV) is a double-stranded DNA virus responsible for a range of mucocutaneous infections. HSV-1 primarily causes orolabial lesions, whereas HSV-2 more commonly affects the genital region. However, either strain can infect any anatomic site depending on exposure. Following primary infection, the virus establishes latency in sensory ganglia, with the potential for reactivation under conditions such as stress, immunosuppression, or febrile illness.

Primary infection may present with fever, malaise, lymphadenopathy, and grouped vesicles on an erythematous base. It can be severe, especially in immunocompromised hosts. Recurrent infections tend to be milder. Other presentations include:

• Herpetic whitlow: painful vesicular lesions on the fingers, typically seen in healthcare workers or thumb-sucking children.
• Eczema herpeticum: widespread HSV infection in patients with atopic dermatitis — a medical emergency due to potential systemic spread.

Diagnosis

Diagnosis is usually clinical. Confirmatory tests are used in atypical or severe cases:

• PCR from vesicle fluid (most sensitive and specific)
• Viral culture (less common)
• Tzanck smear (obsolete)
• Direct fluorescent antibody testing in some labs

Management

• Mild to moderate: Oral aciclovir 400 mg TDS for 5 days (or valaciclovir/famciclovir)
• Severe/disseminated (eczema herpeticum): IV aciclovir
• Recurrent or frequent flares: Suppressive therapy (e.g. aciclovir 400 mg BD for 6–12 months)
• Counselling on avoiding direct contact during active lesions to prevent transmission