Smallpox infection begins with high fever, head and body aches, and sometimes vomiting. A rash follows that spreads and progresses to raised bumps and severe blisters. The blisters scab and fall off after about three weeks, leaving a pitted scar.
How long does it take for symptoms to show? After exposure, it takes between 7 and 17 days for symptoms of smallpox to appear (average incubation time is 12 to 14 days). During this time, the infected person feels fine and is not contagious. Fever is the first symptom, followed two or three days later by a rash that spreads and develops over the next 10 to 14 days.
Is smallpox contagious before the smallpox symptoms show? A person with smallpox is sometimes contagious with onset of fever (prodrome phase), but the person becomes most contagious with the onset of rash. The infected person is contagious until the last smallpox scab falls off.
Smallpox can be confused with Chicken Pox Chicken Pox is less severe and affects the hands and feet less than Smallpox does.
What does smallpox look like? Details of smallpox infection may be found at the CDC's smallpox overview web page.
