Smallpox FAQ

What is smallpox?

Smallpox is a highly contagious infection caused by the variola virus. Naturally occurring smallpox has been eradicated from the globe; the last naturally occurring case of the disease was reported in Somalia in 1977. In May 1980, the World Health Assembly announced the world was free of naturally occurring smallpox and recommended that all countries cease vaccination. Routine vaccination against smallpox ceased in the United States in 1972, and vaccination immunity acquired before that time has undoubtedly waned, as the vaccine does not provide lifelong immunity.

How is smallpox spread?

Smallpox is spread person-to-person, primarily by face-to-face contact with an infectious person. The virus is present in the mouths, noses, throats and skin lesions of infected persons. The smallpox virus is spread through the air when an infected person coughs, sings or talks or spreads by direct contact with infected lesions, contaminated clothing or bed linen.

All persons suspected of having smallpox or having been diagnosed with the illness should be placed in strict isolation. In addition, contacts of infectious cases should be quarantined for 16-17 days following an exposure. All material used in patient care or in contact with smallpox patients should be autoclaved, boiled or burned.

What are the symptoms of smallpox?

The incubation period of smallpox is about 7-17 days; the average being 12 days. Initial symptoms of the disease resemble other acute viral illnesses, such as the flu (malaise, high fever, vomiting, headache and backache). Approximately 2-4 days after onset of illness, a rash appears -- first in the mouth and throat, face and forearms, and then spreads to the trunk and legs. The rash progresses to fluid filled and eventually pus-filled, crusty lesions, which form scabs in 1-2 weeks. The smallpox lesions are most dense on the face and extremities and all develop at the same pace and, on any part of the body, appear identical.

Patients with smallpox are infectious at the onset of the rash and remain infectious until all the scabs have separated (i.e., 3-4 weeks after onset of the rash). In unvaccinated persons, the disease is fatal in approximately 30% of the cases.

How is smallpox diagnosed?

Smallpox is usually diagnosed on clinical grounds; however, the virus can be grown in culture for confirmation.

What is the treatment of smallpox?

There is no specific antibiotic therapy for smallpox. Supportive care is the mainstay of smallpox therapy and antibiotics are used for treating secondary bacterial infections. Administration of vaccinia (smallpox) vaccine within the first days after initial exposure to smallpox virus can reduce symptoms or prevent smallpox disease.

CAn I get a vaccination against smallpox?

A limited amount of a licensed vaccinia (smallpox) vaccine is held by the Centers for Control (CDC) in the United States. In the case of a biological warfare event involving smallpox, the vaccine would be used to vaccinate exposed persons. Because of the small amount of vaccine available, a preventive vaccination program is not an option at this time.