Terrorism101 Home Page : Chemical & Biological Threats : Smallpox
Smallpox
Overview:
Smallpox was eradicated from the world in 1977. In 1980, the World Health Assembly recommended that all countries cease vaccination and that all laboratories destroy their stocks of variola (smallpox) virus or transfer them to one of two World Health Organization reference labs. All countries reported compliance.
The United States cannot, with complete certainty, verify that the virus is not being held in places other than the two WHO reference laboratories; therefore, the deliberate reintroduction of smallpox is regarded as a possibility.
Because this virus is relatively stable (not easily destroyed in the environment) and the infectious dose is small, an aerosol release of variola virus could disseminate widely.
A single suspected case of smallpox would be treated as a health emergency and should be brought to the attention of national officials through local and state health authorities. However, varicella, or chickenpox, which infects millions of children each year in the United States, is the disease most frequently confused with smallpox. (Chickenpox lesions are much more superficial and are almost never found on the palms and soles.)
What is it?
The Variola virus. The incubation period is about 12 days (range: 7 to 17 days) following exposure.
Symptoms:
Initially include high fever, fatigue, and head and back aches followed in 2-3 days by a rash.
Lesions in the mouth and throat that appear early in the illness ulcerate and release large amounts of virus in the saliva. The most visible symptom of smallpox is a rash with lesions most dense on the face, arms and legs. The lesions are round, tense, and deeply embedded in the skin, and appear over a 1 to 2 day period, evolving at the same rate on the body. Lesions become pus-filled and begin to crust early in the second week of the rash. Scabs eventually develop which separate and fall off after about 3-4 weeks.
Treatment:
At this time, there is no proven treatment for smallpox. Patients with the illness would be given non-specific supportive therapy as needed (intravenous fluids, medicine to control fever or pain, etc.) and antibiotics for any secondary bacterial infections that occur.
No antivirals have yet proved effective for treating smallpox; however, research is ongoing.
Case fatality rates range from approximately 1 to 30 percent, with deaths most often occurring during the first or second week of illness.
Prevention:
The United States currently has a limited supply of smallpox vaccine (approximately 15 million doses) available for emergency use, if needed. New methods for the production of additional smallpox vaccine in large quantities are being explored. At this time, no preventive vaccination program is planned.
Smallpox vaccine is very effective and can lessen the severity or even prevent illness in people exposed to smallpox if given up to 4 days after exposure.
Sources: CDC
Terrorism101 Home Page : Chemical & Biological Threats : Smallpox
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