Smallpox is an infection caused by the variola virus. The most commonly known and severe form of variola is called variola major. It is contagious and fatal in approximately 30% of the individuals infected. The last known case of smallpox in the United States occurred in 1949. Smallpox has been considered an eradicated disease since 1977, when the last natural case occurred in Somalia.
The former Soviet Union (now Russia) and the United States have stored samples of smallpox in the national laboratories of their respective countries. There remains a concern that the virus could be used as a bioterrorism agent, which is why it is important for the healthcare establishment to remain vigilant in the proper identification and reporting of smallpox. The confirmation of one case of smallpox would be considered a national public health emergency. Any suspicion of smallpox in a patient should be reported to the health department by the most rapid means possible.
Symptoms usually begin within 12 to 14 days after a person is exposed to the smallpox virus, but can begin anytime between seven and 17 days. The initial symptoms often include fever (101-104 degrees Fahrenheit), weakness, malaise (tired and not feeling good), headache, and generalized body aches. Sometimes vomiting and mental confusion can appear, but not always.
Next, usually two to four days later, a rash emerges. The rash begins in the mouth and then spreads to the face and then on to the arms and legs (including hands and feet), and finally spreads to the rest of the body. The rash looks like raised bumps that fill with a thick fluid and often have a place in the center that sinks. This rash appears over about a 24 hour period of time. Five to 10 days later, the bumps become round, raised and firm pustules. Within two weeks these pustules form a thick crust over the top that become scabs. During the third week of the rash, the scabs fall off, leaving behind deep scars.
Smallpox is spread person-to-person through direct contact with the skin lesions of an infected person. It can also be spread by respiratory droplets, aerosols, bodily secretions. In order to catch small pox from another person, direct and fairly lengthy face-to-face contact is usually necessary. This is defined as being less than six feet from an infected person for more than three hours. Smallpox cannot be spread by animals or insects, however, it can be transmitted through contact with contaminated clothing or bedding.
People are contagious when the rash appears and remains contagious until the rash heals and the last smallpox scab falls off.
There are no proven effective treatments for smallpox. Treatment consists of supportive care and relief of symptoms.
Because smallpox has been eradicated, the vaccine for smallpox is not available for routine use. In the event of an emergency, a vaccination administered within 3 days following a known exposure will prevent the disease or reduce the severity of smallpox symptoms in most people.
Smallpox Information for Healthcare Providers (PDF)
VDH Emergency Preparedness & Response Programs