There
were two clinical forms of smallpox. Variola major is the severe and most
common form, with a more extensive rash and higher fever. Variola minor was a
less common presentation, and a much less severe disease, with historical death
rates of 1% or less. Subclinical (asymptomatic) infections with variola virus
were noted but
were two clinical forms of smallpox. Variola major is the severe and most
common form, with a more extensive rash and higher fever. Variola minor was a
less common presentation, and a much less severe disease, with historical death
rates of 1% or less. Subclinical (asymptomatic) infections with variola virus
were noted but
were not common. In addition, a form called variola sine eruptione (smallpox
without rash) is seen generally in vaccinated persons. This form was marked by
a fever that occurred after the usual incubation period and could be confirmed
only by antibody studies or, rarely, by virus isolation.
