A disease proven to be vaccine preventable

Identification and Definition

*Smallpox is an infectious disease that is contagious and can be fatal. The most common form of smallpox is Variola major which causes a fever and extensive rash. The ordinary type of smallpox Variola major has a fatality rate of around 30% and accounts for about 90% of smallpox cases.

* Smallpox can be prevented by the smallpox vaccine if given to a person before exposure to the disease but vaccination within 3 days after exposure can prevent or lessen the severity of the disease. Smallpox is spread by direct, face to face contact, through bodily fluids, or contaminated objects.

History of Smallpox

The exact origin of smallpox is unknown because it dates back so far, but early evidence is seen in the form of face lesions resembling smallpox on the faces of mummies from ancient Egypt. Smallpox is also described in Indian and Chinese texts suggesting that it was present in African and Asian nations as early as 1122 BC. Smallpox was introduced into European nations between the fifth and seventh centuries and to the United States by early settlers.

The first vaccination for smallpox was developed in the late 1700's and perfected over time. A worldwide vaccination program has eradicated the disease. The last case of smallpox in the U.S was in 1949 and the last naturally occurring case recorded was in Somalia, 1977.

The smallpox vaccine is not currently available to the general public since this disease is not present, but after the terror attacks of 9/11 some concern has been brought up about the smallpox virus being used as an agent of bio-terrorism. The U.S. has a stockpile of vaccine for everyone in the country in the event or threat of such an attack.

Signs and Symptoms

*Smallpox symptoms generally appear after an average of 12-14 days after exposure. This time after exposure, which can range anywhere from 7-17 days, is called the incubation period. In the incubation period people are not contagious and do not show any signs or symptoms, but the disease is in their body.

*The first signs and symptoms that crop up after the period of incubation include:

  • High Fever (101-104 degrees)
  • Malaise
  • Head and body aches
  • Sometimes vomiting

This phase of smallpox lasts for 2-4 days; people in this phase are usually too sick to participate in everyday activities.

*The next phase of smallpox includes a rash that is first observed as spots on the tongue or in the mouth. These spots burst open spreading large amounts of the virus into the mouth and throat. The rash progresses on in the form of:

  • Rash appearing on the skin, starting with the face and spreading to arms, legs, hands, and feet; within 24 hours the rash has spread to all parts of the body
  • After the rash appears, fever reduces
  • Around the 3rd day of the rash, raised bumps replace the rash spots
  • Around the 4th day after the rash appeared, these bumps fill up with fluid and fever may return

This phase of smallpox is usually the most contagious.

*In the next phase, smallpox bumps become pustules or small firm lumps under the skin. This phase last for an average of 5 days.

*These pustules begin to scab over and remain for an average of 5 days.

*Then the scabs fall off and leave behind scars. A person is still contagious at this stage until all scabs have fallen off.

Transmission of Smallpox

  • The most common transmission for the smallpox virus is by airborne droplets which occurs in close, face-to-face contact and greater transmission when that contact is prolonged
  • Smallpox virus can be transmitted through the air, although it is more rare, but occurs in spaces where a cough is present such as a hospital
  • Transmission of smallpox virus through fomites on bedclothes, linens, and blankets is rare but can occur
  • Smallpox cannot be transmitted through food or water


  • Although there is no treatment for smallpox, 70% of people will survive the disease. However, a few varieties of smallpox such as flat and hemorrhagic are always fatal. Pregnant women and people with impaired immune systems are more likely to contract these fatal forms of smallpox or have complications for typical smallpox.
  • Smallpox survivors will have pitted scars from the scabs that form and flake off.
  • Smallpox may also cause blindness in a small sampling of infected peoples.

Smallpox Control Measures

  • Smallpox was controlled and eradicated through the use of vaccines worldwide to help build immunity in the body to the disease.
  • The first dose of the smallpox vaccine provides immunity for 3-5 years and then decreases. Another dose of vaccine will cause immunity to last longer.
  • The U.S. no longer vaccinates against smallpox since the disease has been declared eradicated, but in the event of a threat or action of bio-terrorism using smallpox enough vaccine is available for every person in the country.