Incubation period: 7-19 days
Initial phase begins as a fever, fatigue/weakness, dorsal-lumbar pain, myalgias, nausea/vomiting
2-4 days later the characteristic rash appears
Worst on the face, arms, legs, and includes the palms and soles
Lesions will generally all be at same stage
Lesions begin as clear fluid-filled vesicles, progress to pustules, and then harden and form a crust, ultimately falling off in about 3-4 weeks
Worst on the face, arms, legs, and includes the palms and soles
Lesions will generally all be at same stage
Lesions begin as clear fluid-filled vesicles, progress to pustules, and then harden and form a crust, ultimately falling off in about 3-4 weeks
Variola major and minor (90% of cases)
Variola major
More severe, mortality rate 30%
Variola minor
Less severe, mortality rate 1%
Fewer pox
Other (10% of cases)
Hemorrhagic
Hemorrhages occur within the blisters as well as mucus membranes and internal organs, death usually within 5-6 days
Malignant
Soft, flattened lesions, does not progress to pustules
Resolve without forming scabs 
Variola major
More severe, mortality rate 30%
Variola minor
Less severe, mortality rate 1%
Fewer pox
More severe, mortality rate 30%
Less severe, mortality rate 1%
Fewer pox
Hemorrhagic
Hemorrhages occur within the blisters as well as mucus membranes and internal organs, death usually within 5-6 days
Malignant
Soft, flattened lesions, does not progress to pustules
Resolve without forming scabs 
Hemorrhages occur within the blisters as well as mucus membranes and internal organs, death usually within 5-6 days
Soft, flattened lesions, does not progress to pustules
Resolve without forming scabs
Smallpox
Atopic dermatitis
Tularemia
Bed bugs
Scabies
Contact dermatitis
Measles
Drug rash