What is smallpox?

Smallpox is an acute, contagious, and sometimes fatal disease caused by a virus.

How is smallpox spread?

Smallpox is spread from person to person by coughing and sneezing. Generally this means that there is direct and fairly prolonged face-to-face contact with a sick person.

Persons with smallpox are most likely to spread the disease during the first week of illness. However, it may be contagious until all scabs have fallen off (approximately three weeks). 

What are the symptoms of smallpox?

Symptoms appear between seven and seventeen days for symptoms of smallpox to appear.

The initial symptoms of smallpox appear to be flu-like with high fever, headaches, tiredness, and backaches. About two to four days following the appearance of these symptoms, a rash will develop on the face, arms, and legs at the same time. Initially the rash is red and flat, then it progresses to a raised rash and forms a blister filled with a yellowish-white infectious fluid that will begin to crust over early in the second week. About three to four weeks later, scabs develop, separate, and fall off.

What is the treatment for smallpox?

There is no proven treatment for smallpox, but research is being conducted on new antiviral agents. Strict isolation of persons with smallpox must be done to prevent the spread of the disease.

Are there complications from smallpox?

The majority of persons with smallpox recover. Complications of smallpox may be the following: encephalitis (infection of brain tissue), keratitis (inflammation of the cornea of the eye), and blindness in about 1% of the cases. Many survivors have permanent scars over large areas of their body, especially their face.

Death occurs in up to 30% of the cases.

How can smallpox be prevented?

The only way to prevent smallpox is the use of the smallpox vaccine. Routine vaccination of the American public against smallpox ended in 1972 after the disease was eradicated in the United States. The level of protection, if any, among persons who were vaccinated before 1972 us uncertain; therefore, these persons are assumed to be susceptible.

The vaccine can lessen the severity of or even prevent illness if given within four days of exposure to the disease.

Can smallpox be used as a bio-weapon?

Smallpox could be released in aerosol form, however the virus is fragile. In laboratory experiments, 90% of aerosolized smallpox virus dies within 24 hours. If an aerosol release of smallpox occurs, 90% of virus matter will be inactivated or dissipated in about 24 hours.