Smallpox is a disease caused by a poxvirus that is transmitted from person to person that causes high fever, characteristic rash, and may kill about one-third of those infected. Smallpox is the only disease that has been completely wiped out throughout the world. Smallpox is also potentially one of the most devastating biological weapons ever conceived.
Smallpox usually requires fairly prolonged face-to-face contact to spread. It's most often transmitted through the air by droplets that escape when an infected person coughs, sneezes or talks. In rare instances, airborne virus may spread farther, possibly through the ventilation system in a building, infecting people in other rooms or on other floors. Smallpox can also spread through contact with contaminated clothing and bedding, although the risk of infection from these sources is slight.
The first symptoms of smallpox usually appear 12 to 14 days after you're infected. During the incubation period of seven to 17 days, you look and feel healthy and can't infect others. Following the incubation period, a sudden onset of flu-like signs and symptoms occurs. These include: * Fever
* Overall discomfort
* Severe fatigue
* Severe back pain
* Sometimes vomiting, diarrhea or both
A few days later, flat, red spots appear first on your face, hands and forearms, and later on your trunk. Within a day or two, many of these lesions turn into small blisters filled with clear fluid, which then turns into pus. Scabs begin to form eight to nine days later and eventually fall off, leaving deep, pitted scars. The rash is usually most noticeable on the palms of your hands and the soles of your feet. Lesions also develop in the mucous membranes of your nose and mouth and quickly turn into sores that break open, spreading the virus into your saliva. When smallpox was common, an experienced clinician could make the diagnosis simply by looking at the rash and examining the patient. Any...