A7. Herpes simplex virus (HSV) infections of the skin

Herpes viruses
- α herpes viruses
  - Lie latent in sensory ganglia neurons
  - Replicate quickly
  - Herpes simplex 1
  - Herpes simplex 2
  - Varicella zoster virus
- β herpes viruses
  - Lie latent in leukocytes
  - Human herpes virus 6 – roseola infantum/sixth disease
  - Human herpes virus 7
  - CMV
- γ herpes viruses
  - Lie latent in lymphocytes
  - Human herpes virus 8
  - EBV
  - Are oncogenic
HSV infections
- Labial herpes
  - On lips
  - HSV-1 in 90%
  - HSV-2 in 10%
  - Clinical features
    - Prodromal symptoms – 24 hours before outbreak
      - Pain
      - tingling
      - Burning
    - Recurring, erythematous vesicles that turn into painful ulcerations
  - Complications
    - Herpetic gingivostomatitis
      - In children and immunocompromised
      - Often the primary infection
      - Erythema, painful ulceration on perioral skin and oral mucosa
- Genital herpes
  - On genital organs
  - HSV-2 in most cases
  - HSV-1 rarely
  - Incubation period – 2 – 7 days
  - Clinical features
    - Many are asymptomatic
    - Painful lymphadenopathy
    - Vesicles that ulcerate
- Eczema herpeticum
  - HSV-1, HSV-2
  - On pre-existing skin conditions
    - Atopic dermatitis
  - Extensive disseminated and painful eruptions on head and upper body
  - Erythematous skin with multiple, round vesicles
  - It’s an emergency
  - Treatment -> IV acyclovir
- Herpetic whitlow
  - In children and healthcare workers who come into contact with saliva
  - Direct contact with infected saliva through a break in the skin
  - Pain, burning, oedema in finger
  - Lymphadenopathy
- Treatment
  - Decreases duration and severity
  - Most effective if initiated within 72 hours
  - Mild disease
    - Oral acyclovir (5 x 800mg for 10 days)
  - Severe disease
    - IV acyclovir
  - Acyclovir-resistance -> foscarnet