Monkeypox

A zoonotic viral disease caused by the Monkeypox virus (MPXV)

Aetiology

  • Causative agent: Monkeypox virus (Orthopoxvirus, Poxviridae family)
  • Two genetic clades:
    • Clade I (Central African/Congo Basin) – more severe, higher mortality
    • Clade II (West African) – milder disease, more common globally
Reservoir: rodents (suspected), monkeys accidental hosts

Transmission

  • Animal-to-human:
    • Bites, scratches, direct contact with animal blood, fluids, lesions
  • Human-to-human:
    • Prolonged close contact
    • Respiratory droplets
    • Contact with skin lesions, scabs, contaminated objects
    • Sexual contact (MPXV detected in semen/vaginal fluids)
  • Vertical transmission (placenta → possible congenital mpox)
Incubation period: 5–21 days (average 6–13 days)

Clinical Presentation

Prodromal phase (1–5 days before rash):
  • Fever
  • Headache
  • Myalgia
  • Chills
  • Fatigue
  • Lymphadenopathy (key feature distinguishing from smallpox/varicella)
Exanthem phase:
Rash develops in stages over 2–4 weeks:
Macules → Papules → Vesicles → Pustules → Umbilicated lesions → Scabs
  • Often begins on face → spreads to body
  • Involves palms and soles
  • Lesions can be painful/itchy
  • Genital/anogenital lesions common in recent outbreaks
notion image

Investigations

Clinical findings + epidemiologic history.
Laboratory confirmation:
  • PCR from lesion swab (preferred)
  • Electron microscopy (orthopox virion)
  • Serology possible but cross-reactive with vaccinia/smallpox vaccination

Management

Most cases are self-limiting (recovery in 2–4 weeks).
Supportive therapy:
  • Hydration
  • Antipyretics
  • Pain management
  • Prevent secondary infection
Antivirals recommended for severe cases/high-risk individuals:
  • Tecovirimat (TPOXX) – first-line
  • Cidofovir / Brincidofovir (alternative options)
  • VIGIV (Vaccinia Immune Globulin Intravenous) for severe/complicated mpox
Isolation recommended until lesions fully heal and scabs fall off.