Smallpox


 * Smallpox** is an infectious disease unique to humans, caused by either of two virus variants,//Variola major// and //Variola minor .//The disease is also known by the Latin names //**Variola**// or //**Variola vera .**// Smallpox localizes in small bood vessels of the skin and in the mouth and throat. In the skin, this results in a characteristic maculupapular rash, and later, raised fluid-filled blisters. //V. major//produces a more serious disease and has an overall mortality rate of 30–35%. //V. minor// causes a milder form of disease which kills about 1% of its victims. Long-term complications of //V. major// infection include characteristic scars, commonly on the face, which occur in 65–85% of survivors. Blindness resulting from corneal uceration and scarring, and limb deformities due to arthritis and osteomyelitis are less common complications, seen in about 2–5% of cases. Smallpox is believed to have emerged in human populations about 10,000 BC..



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

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