OVERVIEW

  • Viral zoonotic infection
  • Incubation period 6-13 days
  • Causes rash similar to smallpox
  • Person-to-person transmission and mortality is significantly lower than smallpox

TRANSMISSION

  • Human-to-human
    • Bodily fluids
    • Cutaneous lesions
    • Respiratory droplets — requires prolonged face-to-face contact
  • Animal-to-human (zoonotic)
    • Bodily fluids
    • Cutaneous lesions

CLINICAL FEATURES

The majority of infections are asymptomatic.

Symptomatic infection can be divided into two phases:

1. Invasion period

  • Fever
  • Myalgia
  • Headache
  • Lymphadenopathy (distinguishing feature from smallpox) — submandibular, cervical, inguinal

2. Skin eruption period (1-3 days after fever) causes a characteristic rash

  • Initially maculopapular
  • Transiently starts on trunk and spreads peripherally to face, palms, and soles of feet
  • Progresses over 2-4 weeks to vesicles, pustules, followed by scabbing and desquamation
  • Localised rash on hand(s) can occur following direct contact with infected animal or human
Monkeypox UK Health security agency
Images of individual monkeypox lesions. Monkeypox. UK Health security agency

INVESTIGATIONS

  • Viral PCR

DIFFERENTIAL DIAGNOSIS

  • Varicella (chickenpox)
    • Vesicular lesions in varicella are often in different stages of development and healing
    • This differs from monkeypox, where lesions are generally all at the same stage
  • Smallpox
    • Lymphadenopathy is a key distinguishing feature of monkeypox

MANAGEMENT

Management is generally supportive. Most symptomatic patients have mild self-limiting disease.

More severe cases or immunocompromised patients may require specific antiviral treatment:

  • Cidofovir — no clinical data for efficacy in humans, can cause nephrotoxicity
  • Tecovirimat
  • Brincidofovir (analogue of cidofovir)

COMPLICATIONS

  • Secondary skin infection
  • Bronchopneumonia
  • Sepsis
  • Encephalitis
  • Corneal infection with ensuing visual loss

Mortality has historically ranged from 0-10%. Only three previous outbreaks have occurred:

  • Central Africa 1996-1998, mortality ~10%
  • USA 2003, mortality 0%
  • Nigeria 2017-present (~200 confirmed cases), mortality 3%

References

Tweetorials

Guidelines

Publications


Critical Care

Compendium

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM with a passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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