Fact sheet on smallpox
Clinical Features:
Incubation: 7-17 days
Natural History
- Febrile 2-4 days with fever, rigors, malaise, headache, backache, and vomiting (Occasionally delirium, transient early rash)
- Acute papular dermatitis on face, hands, forearms, spreading to lower extremities and trunk
- Synchronous progression: papule to vesicle to pustule
- Scabs over on days 8-14 after onset of fever
- Scabs slough off 14-28 days after fever onset
Expected Delivery Method(s)
- Infected persons entering and mingling with local residents. This would be difficult to execute, as the period of maximum viral shedding is after the patient becomes obviously ill.
- Aerosol release
- Point source
- Line source
- Both of these would be difficult, as the agent has not been successfully weaponized in the West.
Precautions
Decontamination:
- Patients and clothing are highly contagious.
- Clothing and linen must be sterilized in an autoclave or by boiling.
- Hard surfaces can be cleaned with quartenary ammonium, phenolic, or 5% bleach solutions. Allow contact for at least four hours.
Contagious?
- Patients, linens, and everything else the patient touched are highly contagious, as is the area in which droplets from the patient may have landed.
Isolation:
- Strict isolation is required. This requires a combination of:
- Contact isolation
- Droplet precautions
- Universal precautions
- Cohorting of patients is encouraged.
- Contacts need to be immunized and quarantined for 17 days.
- Home quarantine also is an option, but will require supports (such as food deliveries) to allow people to remain at home for the duration.
Prophylaxis:
- Immunization is usually protective if done within 24 hours of exposure.
Treatment
- First, do everything possible to limit spread.
- Use primarily supportive care.
- There is a Smallpox Immune Globulin, but its supply is limited, as is its efficacy.
- Cidofovir may be effective.
Source: Charles Werntz, MD, Department of Community Medicine, West Virginia University, Morgantown, and Janet Williams, MD, West Virginia University Center for Rural Emergency Medicine, Morgantown.
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