Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 6-21: Variola (Smallpox) & Vaccinia + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Prodromal high fever Eruption progressing from papules to vesicles to pustules, then crusts All lesions in the same stage Face and distal extremities (including palms and soles) favored +++ General Considerations ++ Recent reintroduction of vaccination for first-responder and military population because of bioterrorist threat The incubation period for smallpox averages 12 days (7–17 days) Immunization with vaccinia is not recommended for persons with eczema, in whom widespread vaccinia (eczema vaccinatum) may result, with lesions resembling those of smallpox Exposure to a recently vaccinated person may lead to generalized disease in persons with certain skin diseases Prior vaccination does not prevent generalized vaccinia, but previously vaccinated individuals have milder disease Progression of the primary inoculation site to a large ulceration occurs in persons with systemic immune deficiency, with a possible fatal outcome + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs +++ Smallpox ++ Prodrome Abrupt onset of high fever Severe headaches, and backaches Infected person appears quite ill Infectious phase Appearance of an enanthem, followed in 1–2 days by a skin eruption Lesions begin as macules, progressing to papules, then pustules, and finally crusts over 14–18 days The face is affected first, followed by the upper extremities, the lower extremities, and trunk, completely evolving over 1 week Lesions are relatively monomorphous, especially in each anatomic region All lesions in same stage of development differentiates rash from varicella +++ Vaccinia ++ Inoculation with vaccinia produces a papular lesion on day 2–3 that progresses to an umbilicated papule by day 4 and a pustular lesion by the end of the first week The lesion collapses centrally, and crusts, with the crust eventually detaching up to a month after the inoculation +++ Differential Diagnosis ++ Generalized varicella zoster virus (VZV) infection Generalized herpes simplex virus (HSV) + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Direct fluorescent antibody testing for HSV and VZV are first-line diagnostic tests to differentiate VZV, HSV, vaccinia, and smallpox Smallpox is a clinical diagnosis but viral infection can be confirmed by electron microscopy, antigen detection, and polymerase chain reaction + Treatment Download Section PDF Listen +++ +++ Medications ++ No specific and proven antiviral therapy for vaccinia or smallpox Vaccinia immune globulin is used to treat eczema vaccinatum and progressive vaccinia Cidofovir may have some activity against these poxviruses +++ Therapeutic Procedures ++ Strict respiratory and contact isolation crucial Patient should be immunized if in early stage of disease No antiviral therapy clearly effective Supportive care critical Centers for Disease Control and Prevention should be contacted immediately in the event of suspected case(s) + Outcome Download Section PDF Listen +++ +++ Complications ++ Serious complications in about 5/100,000 persons include encephalitis, progressive vaccinia, and eczema vaccinatum +++ Prognosis ++ Generalized vaccinia may be fatal +++ Prevention ++ U.S. vaccination campaign voluntary, focusing on first responders and military personnel +++ When to Admit ++ Until the diagnosis is confirmed, strict isolation of the patient is indicated + Reference Download Section PDF Listen +++ + +https://www.cdc.gov/smallpox/index.html