Diagnosis
In evaluating suspected index cases of smallpox, health care personnel must wear masks, gowns, and gloves and observe universal precautions. Extreme caution must be exercised in collecting diagnostic specimens. Electron microscopy of vesicular scrapings demonstrates the typical brick-shaped smallpox virions. Monkeypox, which can appear identical to smallpox, should be considered in individuals who have recently traveled to endemic areas in Africa. More than 23 human cases of this zoonosis were reported in the midwestern United States in June 2003, spread by prairie dogs that apparently contracted the disease from rats imported from Africa.[27] The characteristic clinical presentation of variola with synchronous, centrifugal distribution of lesions on the distal extremities and face makes misdiagnosis unlikely. Light microscopy of clinical specimens stained with silver stain displays Guarnieri bodies, cytoplasmic inclusions composed of aggregations of variola virions. Additionally, viral isolation using tissue culture techniques and identification of particular variola strains using molecular biology techniques, such as polymerase chain reaction[28] and restriction fragment-length polymorphism analysis, can be performed by government laboratories.
In suspected cases of smallpox, strict isolation should be instituted and maintained while awaiting public health response teams to evaluate the patient. Local health departments, hospital infection control officers, and the Centers for Disease Control and Prevention (CDC) should be notified immediately.
Skinmed. 2004;3(4) © 2004 Le Jacq Communications, Inc.
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