UMEM Educational Pearls

Category: International EM

Title: Smallpox- The Deadly Scourge

Keywords: Smallpox, public health, infectious diseases (PubMed Search)

Posted: 7/19/2014 by Jon Mark Hirshon, MD, MPH, PhD
Click here to contact Jon Mark Hirshon, MD, MPH, PhD

·      Smallpox (Variola):

o   Only eradicated human infectious disease. 

o   Prior to the advent of vaccination, it killed an estimated 400,000 Europeans annually and was a major cause of blindness.


·      Major potential as a bioterrorism agent:  

o   Now only supposed to exist in two laboratories in the world (at the CDC in Atlanta, Georgia and in the Vector Institute in Koltsovo, Russia).


·      Recently, previously unknown vials of active virus from the 1950s were found in a NIH laboratory in Maryland.


·      Clinical Presentation:

o   Incubation is usually 10-12 days (range 7-17 days)

o   Signs and symptoms include:

§  Febrile (38.8-40.0C) prodome lasting 1-4 days, headache, myalgia (esp. back/spinal pain), pharyngitis, chills, abdominal pain

§  Rash: classically round and well circumscribed.  May be confluent or umbilicated. The rash evolves slowly: macules to papules to pustules to scabs.


·      It is important to differentiate smallpox from chicken pox (Varicella): 

o   Smallpox: Significant prodrome. Centrifugal rash (trunk to extremities). Can involve soles and palms. Lesions are in the same stage of development on any one part of the body.

o   Chickenpox: Minimal prodrome. Centripetal rash (extremities to trunk). Seldom on soles and palms. Asynchronus evolution of rash.


Bottom Line:

Smallpox is a global public health emergency and requires immediate reporting.  If the clinical presentation is unclear, discuss with local infectious disease experts or public health officials.