Feature |
Smallpox (Variola) |
Chickenpox (Varicella) |
Causative agent |
Variola virus (Orthopoxvirus) |
Varicella-zoster virus; VZV (Herpesvirus family) |
Incubation period |
12 days (7-17 days) |
15 days (10-21 days) |
Rash |
• Deep seated • Appear in single stage • Evolution is slow |
• Superficial • Appear in crops (Pleomorphic) • Evolution is rapid • Dew drop rashes |
Rash |
• Centrifugal • More concentrated on • Extensor surface |
• Centripetal • More concentrated on • Flexor surface |
Fever |
Subsidies with appearance |
Rise with each crop |
NOTE: In 1980, the WHO declared that smallpox was eradicated.