Chicken Pox vs. Small Pox

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In smallpox, lesions are commonly found on the palms and soles. In chickenpox, however, there are very few or no lesions on the palms and soles.

In smallpox, fever is present for 2 to 4 days before the rash begins, while with chickenpox, fever and rash develop at the same time.

All the pocks of the smallpox rash are in the same stage of development on any given part of the body and develop slowly. In chickenpox, the rash develops more rapidly, and vesicles, pustules, and scabs may be seen at the same time.

Small Pox

• Evolution: Centripetal distribution - eruption starts from the face and extremities towards the body
• Rashes: Pocks present on palms and soles
• Associated Symptoms: Malaise, fever, rigors, vomiting, headache and backache
• Incubation Period: 7 to 17 days after close contact with a smallpox patient
• Prodromal Period: Prolonged and severe; systematic manifestations are more pronounced
• Fever: High grade fever
• Scabs: Forms 10 to 14 days after appearance of rash and may be infectious; fall off 14 to 28 days after rashes appear
• Characteristics: Multilocular, areas of the body (areas of the pressure and tight skin), hard shotty discrete and deep lesions
• Vesicles: Do not collapse on puncture

Chicken Pox

• Evolution: Centrifugal distribution - eruption starts from the trunk and spread to exposed parts or away from the center
• Rashes: Pocks seldom present on palms and soles
• Associated Symptoms: None
• Incubation Period: 14 to 21 days after close contact with chicken pox patient
• Prodromal Period: Milder constitutional manifestations with less complications
• Fever: Low grade fever
• Scabs: Form 4 to 7 days after appearance of rash and may not be infectious; fall off within 14 days after rashes appear
• Characteristics: Unilocular, over the body (exposed parts of the body), skin superficial lesions
• Vesicles: Collapse on puncture