[Smallpox (variola)].

Symptoms in the initial stage of smallpox included fever, chills, headache, nausea, vomiting and severe muscle aches. This stage would usually last for two to four days and was, at times, accompanied by flushing of the skin. By the fourth day of illness, the fever dropped and the characteristic smallpox rash appeared. The rash started out as flat or slightly thickened spots (known as macules) and quickly progressed to raised spots (known as papules). These papules continued to enlarge and became filled with a clear fluid. The lesions were then referred to as vesicles. The fluid in the vesicles would gradually change from clear to pus-like, and the lesions were then referred to as pustules. During the pustule stage, a fever would again be common and the pustules would start to form into scabs. Over time, the dried scab material would fall off of the skin. This entire process took three to four weeks, and the areas affected by the rash were often permanently scarred.