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Smallpox (variola major) | ||
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Identification
Smallpox, derived from the Latin word meaning "spotted," is a serious and often deadly infectious disease caused by a form of the variola virus, an ancient virus that has caused epidemics for thousands of years. Due to the development of a vaccine, smallpox was eradicated following a successful worldwide vaccination program. The last recorded case of smallpox in the United States was in 1949. Pathogenesis Transmission of the disease generally requires prolonged close contact with a person who has initial symptoms. It can also be spread through body fluids, such as saliva. The incubation period is about 7-14 days. Individuals who have not yet acquired symptoms, during the incubation period, are not contagious. Since only a small amount of the virus is required for infection, smallpox is an ideal candidate for aerosol release. After entry into the body, the virus rapidly migrates to the lymph nodes and localizes in the small blood vessels of the dermis. Fever and toxemia occurs by the 8-12th day following infection. Death most commonly occurs from toxemia. Manifestations After the 7-14 day incubation period a person develops the initial symptoms of the disease, including aches, pains, fatigue, and fever (101-104 degrees F). Approximately 2-4 days following initial symptoms, the characteristic bumpy lesions appear. A person in this stage of the disease is the most contagious. After about two additional weeks following the appearance of the rash, the pustules begin to form a crust and scab over. The person is most infectious during the 7-10 days after the rash appears. Treatment There are no proven treatment methods at this time. Prevention A vaccine is available to those at high risk of infections, including health care workers, first responders, and military personnel. The smallpox vaccine is a "live" vaccine and, thus, there are additional side-effects to consider before deciding get vaccinated. Generally, the vaccine provides a high level of protection against the disease for about five years. Without the vaccine, it is nearly impossible to prevent infection.
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Category A | ||
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Yersinia pestis
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| Category B | ||
| Brucella sp.
E. coli 0157:H7 Vibrio cholerae Cryptosporidium parvum Ricinus communis | ||
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| Category C | ||
| Nimpah Virus
Hantavirus | ||
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Images | ||
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Pock marks on the leg of a smallpox victim
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Smallpox | ||
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