Post-Event Operational Issues

Variola Major: Clinical Types

There are several clinical types of smallpox that are generally differentiated based on the rash characteristics. The following are the different types of smallpox:

  1. Ordinary (classic) type, which is characterized by raised, pustular lesions. Ordinary type smallpox can come in three different forms: Confluent (confluent rash on face and forearms), Semi-Confluent (confluent rash on face, discrete elsewhere) and Discrete (areas of normal skin between pustules, even on face).
  2. Modified type smallpox, which is like ordinary type but with an accelerated and less severe course.
  3. Variola Sine Eruptione is characterized by a fever without rash caused by variola virus, serological confirmation required. This type of smallpox occurs in vaccinated individuals that probably have enough immunity to blunt the development of the full clinical illness and is evident by a significant rise in neutralizing antibody titer.
  4. Flat type smallpox is characterized by pustules remain flat, usually confluent or semi-confluent. It is one of the most severe clinical forms and associated with a very high mortality rate.
  5. Hemorrhagic type smallpox causes widespread hemorrhages in skin and mucous membranes.

Hemorrhagic smallpox can be either the Early form which produces a purpuric rash, or Late form which causes hemorrhage into base of lesions. This type of smallpox, either Early or Late form, is one of the most severe clinical forms and associated with a very high mortality rate. 

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