Key Info

Signs and Symptoms: Clinical manifestations begin acutely with malaise, fever, rigors, vomiting, headache, and backache. Two to 3 days later, lesions appear which quickly progress from macules to papules, and eventually to pustular vesicles. They are more abundant on the extremities and face, and develop synchronously.

Diagnosis: Neither electron nor light microscopy are capable of discriminating variola from vaccinia, monkeypox, or cowpox. Culture and polymerase chain reaction (PCR) diagnostic techniques are more accurate in discriminating variola and other Orthopoxviruses.

Treatment: At present, there is no effective chemotherapy, and treatment of a clinical case remains supportive.

Prophylaxis: Immediate vaccination or revaccination should be undertaken for all personnel exposed.

Isolation and Decontamination: Patients should be considered infectious from onset of rash until all scabs separate and should be isolated using droplet and airborne precautions during this period. In the civilian setting, strict quarantine of asymptomatic contacts for 17 days after exposure may prove to be impractical and impossible to enforce. A reasonable alternative would be to require contacts to check their temperatures daily. Any fever above 38°C (101°F) during the 17 days after exposure to a confirmed case would suggest the development of smallpox. The contact should then be isolated immediately, preferably at home, until smallpox is either confirmed or ruled out and remain in isolation until all scabs separate.
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