What is Smallpox?
Smallpox is a contagious and sometimes fatal disease caused by two related viruses: variola major and variola minor. Variola major is the more common and severe form, with an overall historical fatality rate of about 30%. Variola minor is less common and causes a milder form of smallpox that is usually not fatal. Smallpox eradication was one of the greatest successes of modern public health.
The portal of entry for variola virus is usually through the oropharyngeal or respiratory mucosa(nose). The virus also can enter through the skin, and rarely, through the conjunctiva(eyes).
The virus migrates rapidly to regional lymph nodes.
Incubation of the disease averages 12 to 14 days. During this stage, the newly infected person may feel fine or have very mild symptoms. The virus is not contagious at this stage