| SMALLPOX (Variola) |
CHICKENPOX (Varicella) |
| Smallpox
incubation |
7-17 days |
Chickenpox
incubation |
14-21 days |
| Smallpox
prodrome (illness prior to rash) |
2-4 days |
Chickenpox
prodrome (illness prior to rash) |
minimal/none |
| Smallpox
distribution |
1. Lesions initially tend to develop on the face and extremities, progressing to the trunk of the body.
2. Rash found on palms and soles. |
Chickenpox
distribution |
1. Lesions initially tend to develop on the trunk of the body, progressing to the face and extremities. Lesions also tend to be more abundant on trunk than on face and extremities. 2. Rash rarely found on palms and soles. |
|
Smallpox
depth of rash |
Deeply embedded |
Chickenpox
depth of rash |
Superficial |
| Smallpox
progression of rash |
Lesions develop and progress at the same rate. |
Chickenpox
progression of rash |
Lesions appear successively and progress at varying rates. |
| Smallpox
scab formation |
10-14 days after rash onset |
Chickenpox
scab formation |
4-7 days after rash onset |
| Smallpox
scab separation |
14-28 days after rash onset |
Chickenpox
scab separation |
<14 days after rash onset |
| Smallpox
communicable period |
From rash onset until all scabs have separated (3-4 weeks after onset of rash). Most infectious during the first week of rash, after prodrome. |
Chickenpox
communicable period |
As long as 5 days (but usually 1-2 days) before rash onset until all lesions are crusted (usually) about 5 days after rash onset). Most infectious 1-2 days before rash onset and for first few days of rash. |
