Signs and Symptoms of Monkeypox
Monkeypox presents with a characteristic biphasic illness beginning with a prodromal phase of fever, severe headache, lymphadenopathy, myalgia, and fatigue, followed 1-3 days later by a centrifugal rash that progresses through distinct stages from macules to pustules to scabs. 1, 2
Prodromal Phase (Initial Symptoms)
The illness begins after an incubation period of 5-21 days (typically 7-14 days) with non-specific systemic symptoms: 1, 3, 4
- High fever - often the first presenting symptom 1, 2
- Severe headache - a prominent feature distinguishing it from other viral illnesses 1
- Lymphadenopathy - swollen lymph nodes, which is a key distinguishing feature from smallpox 1, 2, 4
- Myalgia - muscle aches and widespread body pain 1, 3
- Fatigue and malaise - profound exhaustion 1, 5
- Back pain - characteristic complaint 5
- Chills - accompanying the fever 2, 4
Rash Phase (Eruptive Stage)
The characteristic skin lesions typically appear 1-3 days after fever onset: 1
Distribution Pattern
- Centrifugal distribution - the rash is more concentrated on the face and extremities (including palms and soles) rather than the trunk 1
- Face is typically most heavily affected 1
- Extremities show prominent involvement 1
Lesion Progression
The rash follows a predictable Jennerian progression through distinct stages: 4
- Macules - flat, discolored spots appear first 4
- Papules - raised lesions develop 4
- Vesicles - fluid-filled blisters form 4
- Pustules - lesions become pus-filled 4
- Crusts/scabs - lesions eventually scab over and heal 4
Important Clinical Features
- All lesions in a given area tend to be in the same stage of development simultaneously, unlike varicella (chickenpox) where lesions are in different stages 1
- Lesions are often painful 2
- The rash can involve oral mucosa 1
Recent Outbreak Variations (2022-Present)
The 2022 outbreak has shown atypical presentations that differ from classic descriptions: 2
- Anogenital lesions have emerged as the predominant feature in many cases 2
- Some patients present with localized rather than disseminated rash 2
- The typical centrifugal distribution may not always be present 2
Clinical Course and Duration
- Symptoms typically last 2-4 weeks 1
- The disease is usually self-limiting in immunocompetent individuals 1, 2
- Patients remain infectious until all scabs have separated 1
Critical Diagnostic Pitfall
Monkeypox can be difficult to distinguish from other pox-like infections based on clinical presentation alone, particularly in atypical cases, making laboratory confirmation essential for definitive diagnosis. 3, 5 The key distinguishing feature from smallpox is the presence of lymphadenopathy, which occurs in monkeypox but not in smallpox. 1, 2