• Highly infectious after aerosolization.
• Person-to-person transmission can occur via droplet nuclei or aerosols expelled from the oropharynx and by direct contact
• Contaminated clothing or bed linens can also spread the virus
• About 30% of susceptible contacts will become infected

Smallpox incubation period is 12-14 days. Characteristic rash appears 2-3 days after nonspecific flu-like prodrome (fever and headache). Maculopapular rash begins on mucosa of mouth and pharynx, face, hands, forearms, and spread to legs and centrally to trunk; lesions are more predominate on the face and extremities than on the trunk. Lesions progress synchronously on any given part of the body from macules to papules to vesicles to pustules to crusty scabs.


Mask and gloves should be worn by person obtaining specimen, preferably a person who has been recently vaccinated. Vesicular fluid is obtained by opening lesions with the blunt edge of a scalpel, harvesting fluid with a cotton swab; scabs can be removed by forceps. Swabs and scabs should be placed in a vacutainer, sealed with tape, and placed in a second, durable, water-tight container. Laboratory specimens must be handled in a bio-safety level 4 facility and will be evaluated with electron microscopy and cell culture. Airborne isolation in a negative pressure room using N-95 respirator mask from onset of rash until all scabs separate is necessary for patient isolation, and laundry and waste should be autoclaved before being laundered or incinerated.


Supportive care is the mainstay of therapy. In-vitro antiviral activity against poxviruses has been shown with adefovir, idofovir, dipivoxil, and ribavirin (animal studies suggest that cidofovir may be most effective). Smallpox vaccine would be required for all persons exposed at the time of the bioterrorist attack or anyone with close personal contact with a smallpox case. Vaccine is most effective if given before or within 3 days of exposure. Ideally, all exposed persons should be placed in strict quarantine for 17 days after last contact with a smallpox case.